GUIDEBOOK TO CONSTRUCTING
INEXPENSIVE SCIENCE TEACHING EQUIPMENT
Volume II: Chemistry
Inexpensive Science Teaching Equipment Project
Science Teaching Center
University of Maryland, College Park
U.S.A.
fc) Copyright. The contents of this Guidebook are open to the public domain except
for those items which have been taken directly (as opposed to adapted) from other
sources, and which are identified within the text by the symbol (Q . Permission to
reproduce copyright items should be obtained directly from the relevant authors.
June, 1972
Inexpensive Science Teaching Equipment Project
Science Teaching Center
University of Maryland
Project Director and Administrator
J. David Lockard
Survey Team
Mary Harbeck
Maria Penny
1968-72
1968-70
1968-70
Guidebook Director
Reginald F. Melton 1970-72
Writing, Drawing and Equipment Development Team
Reginald Melton 1970-72
John Delaini 1970-72
Donald Urbancic 1970-71
Ruth Ann Butler 1971-72
Technical Assistants
David Clark 1970-72
Chada Samba Siva Rao 1970-71
>**:.
t*
CONTENTS
The Guidebook is presented in three volumes:
Volume I, Biology
Volume IJChemistry
Volume II,TPhysics
The following table refers only to the contents of this
volume, but the listing at the back of each volume provides an
alphabetical index to all three volumes.
References within the text normally indicate the volume,
chapter and number of the item referred to (e.g., BI0L/V/A3),
but where a reference is to an item within the same volume
the reference indicates only the chapter and number of the
item (e.g. , V/A3) .
-11 ■
n
ii
c.
D.
Table of Contents
Foreword
Raw Materials and Tools Required
I. GLASSWARE TECHNIQUES AND ACCESSORIES
A. BURNERS, TOOLS, AND EQUIPMENT
B. GLASS
SAFETY
PROCEDURES FOR GLASS TUBING AND RODS
Dl . Cutting
D2 . Bending
D3. Stretching
D4. Fire Polishing Tubing
D5. Closing Tubing
D6. Glass Blowing
D7. Making Rim in Tubing
D8. Finishing Ends of Rods
E. GLASS SHEET OPERATIONS
El. Cutting
E2. Drilling a Hole
F. BOTTLE AND JAR TECHNIQUES
Fl. Etching
F2 . Cutting
G. STOPPERS
Gl. Cork Boring
G2 . Cork Drilling
G3 . Inserting Glass Tubing Through a Stopper
BURNERS
SOLID FUEL BURNERS
Al. Candle Burner
A2 . Charcoal Burner
LIQUID FUEL BURNERS
Bl. Simple Alcohol Burner
B2 . Modified Alcohol Burner
GAS BURNERS AND SYSTEMS
CI. Fuel System for Gas Burner
c2. Gas Burner
C3. Wing Tip
Page
vii
x
:
2
4
6
a
9
12
13
14
15
16
17
19
20
22
24
29
30
32
33
34
35
36
3a
40
43
49
54
•Ill-
III.
MEASURING APPARATUS
i-
U
A. DEMONSTRATION DEVICES
Al . Demonstration Thermometer
A2 . Bi-Metal Strip
B. VOLUMETRIC MEASURES
Bl. Burette
B2. Measuring Glass
B3. Dropper
B4. Pipette
B5. Volumetric Flasks
B6. Specific Gravity Bottle
IV. SUPPORTS; STANDS, AND HOLDERS
A. HOLDERS
Al. Tweezers (Forceps)
A2 . Multi-purpose Design Holder
A3. Test Tube Holder
A4 . Wooden Pinch Clamp
A5 . Wooden Screw Clamp
B. SUPPORTS AND STANDS
Bl. Wire Gauze
B2. Heating Shelf
B3 (1) . Tripod (Tin Can)
B3(2). Tripod (Strapping)
B3 (3) . Tripod (Wire)
B4
B5
B6
B7
B'
BIO.
Collapsible Heating Stand
Ring and Burette Stand with Attachments
Multipurpose Stand
Rack for Light Bulb Glassware
Stand for Light Bulb Glassware
Bamboo Test Tube Rack
Wooden Test Tube Rack
GLASSWARE AND CROCKERY
A. GLASSWARE
Al . Light Bulb Glassware
A2 . Beaker
A3. Funnel
A4. Bell Jar
A5 . Watch Glass
A6. Petri Dish
A7. Wash Bottle
57
59
61
64
66
67
68
69
72
73
76
78
80
82
83
84
86
87
88
90
98
100
102
103
105
106
107
109
110
111
112
113
114
A8 . Aspirator 117
B. CROCKERY
Bl. Mortar and Pestle 120
VI, SEPARATORS AND PURIFIERS 124
A. MECHANICAL SEPARATORS
Al. Magnets 125
A2 . Cone Sieve 126
A3. Basket Sieve 127
A4. Suction-Filter Flask 129
A5 . Separatory Funnel 132
B. DISTILLATIONAPPARATUS
Bl. Simple Distillation Apparatus 136
B2 . Condenser 138
B3. Water Still 141
C. ELECTRIC-SEPARATOR
CI. Electrolysis Apparatus 145
D. CENTRIFUGAL SEPARATORS
Dl. Hand Drill Centrifuge 149
D2 . Centrifuge 153
VII. GAS GENERATORS 162
A. GAS GENERATORS
Al. Simple Gas Generator and
Collecting Apparatus 163
A2. Flask Generator 165
A3. Kipp's Generator 167
B. ACCESSORIES
Bl. Beehive Shelf 173
B2 . Metal Sheet Shelf 174
VIII. METALWARE AND CLEANER 175
A. METALWARE
Al. Flame Test Wire 176
A2. Deflagrating "Spoon" 177
A3. Spatula 178
B. CLEANER
Bl. Test Tube Cleaner or Spatula 179
IX. HEATERS AND DRYERS 180
A. DRYERS
Al. Dessicator 181
A2. Drying Tower 183
A3. Electric Lamp Dryer 185
A4. Sand Bath 188
A5. Water or Steam Bath 189
B. HEATER
Bl. Blowpipe for Charcoal Block 191
X. MOLECULAR MODELS 192
A. SPACE-FILLING MODELS
Al. Ball-and-StickModels 193
B. SKELETAL MODELS
Bl. Molecular Model Units 198
B2. Single Bond Structures 203
B3. Double Bond Structures 207
B4 . Triple Bond Structures 213
B5. Geometric Structures 215
C. CRYSTAL STRUCTURE MODELS
CI. Crystalline Packing Models 217
D. KINETIC-MOLECULAR MODEL
Dl . Kinetic Theory Model 220
XI. CHROMATOGRAPHIC APPARATUS 223
A. QUALITATIVE CHROMATOGRAPHIC APPARATUS
Al. Horizontal Paper Chromatography Device 224
A2 . Horizontal Paper Chromatography Device 226
A3. Horizontal Paper Chromatography Device 228
A4. Vertical Paper Chromatography
Eguipment 230
A5 . Vertical Strip Paper Chromatography
Equipment 234
B. QUANTITATIVE CHROMATOGRAPHIC EQUIPMENT
Bl. Liquid-Column Apparatus 237
XII. MULTIPURPOSE SYRINGES
241
A. TECHNICAL DEVICES
Al. Dropper/Pipette
A2 . Pump
B. GAS STUDIES APPARATUS
Bl. Gas Production and Collection Device
Micro-Generator
B2.
B3.
Gas Solubility Device/Reaction
Rate Chamber
Charles' Law: Volume/Temperature
Device
C
DI FFUSION APPARATUS
CI. Liquid Diffusion Device
C2 . Gas Diffusion Device
D. OXIDATION APPARATUS
Dl. Oxidation Indicator: Membrane Type
D2. Oxidation Indicator: Displacement Type
D3. Oxidation Rate Indicator
D4. Stoichiometry Device
E. ANALYTICAL APPARATUS
El. Air Composition Device
E2. Gas Reaction Chamber
F . CONDUCTANCE APPARATUS
Fl . Conductance Device
F2 . Constant Volume Conductance Device
Bibliography
Alphabetical Index
242
243
245
249
250
252
254
255
258
260
262
263
266
268
270
273
276
278
FOREWORD
History
The Inexpensive Science Teaching Equipment Project was initiated by Dr. J. David
Lockard, and got underway under his direction in the summer of 1968. Originally entitled
the Study of Inexpensive Science Teaching Equipment Worldwide (IS-TEW or IS-2 Study),
the Project was to (1) identify laboratory equipment considered essential for student
investigations in introductory biology, chemistry and physics courses in developing
countries; (2) improvise, wherever possible, equivalent inexpensive science teaching
equipment; and (3) produce designs of this equipment in a Guidebook for use in develop-
ing countries . Financial support was provided by the U.S. Agency for International
Development through the National Science Foundation.
The initial work of the Project was undertaken by Maria Penny and Mary Harbeck
under the guidance of Dr. Lockard. Their major concern was the identification of
equipment considered basic to the teaching of the sciences at an introductory level.
An international survey was conducted, and a list of equipment to be made was compiled.
A start was also made on the writing of guidelines (theoretical designs) for the
construction of equipment.
Work on the development of the Guidebook itself got underway in 1970, with the
arrival of Reginald F. Melton to coordinate the work. Over 200 guidelines were completed
during the year by Donald Urbancic (Biology) , Chada Samba Siva Rao and John Delaini
(Chemistry), and Reginald Melton (Physics). Full use was made of project materials from
around the world which were available in the files of the International Clearinghouse on
Science and Mathematics Curricular Developments, which is located in the Science
Teaching Center of the University of Maryland. The guidelines were compiled into a
draft edition of the Guidebook which was circulated in September, 1971, to some 80
science educators around the world for their comments and advice.
The work of constructing and developing equipment from the guidelines, with the
subsequent production of detailed designs, began in a limited way in 1970, the major
input at that time being in the field of chemistry by Chada Samba Siva Rao, who was
with the project for an intensive two-month period. However, the main work of developing
detailed designs from the guidelines was undertaken between 1971 and 1972 by John Delaini
(Biology), Ruth Ann Butler (Chemistry) and Reginald Melton (Physics) . Technical
assistance was given by student helpers, with a special contribution from David Clark,
who was with the project for a period of 18 months.
LA
Thanks are due to those graduates, particularly SamuelGenova, Melvin Soboleski
and Irven Spear, who undertook the development of specific items of equipment while
studying at the Center on an Academic Year Institute program; to student helpers,
especially Don Kallgren, Frank Cathell and Theodore Mannekin, who constructed the
equipment; and to Dolores Aluise and Gail Kuehnle who typed the manuscripts.
Last, but not least, special acknowledgement is due to those individuals, and
organizations, around the world who responded so willingly to the questionnaires in
1968 and to the draft edition of the Guidebook in 1971.
The Guidebook
The designs presented in the Guidebook are based on the premise that many students
T"~! and teachers in developing countries will wish to make equipment for themselves. This
I j does not mean that students and teachers are expected to produce all their own apparatus i
requirements. It is recognized that teachers have specific curricula to follow, and that 1
..] j "class hours" available for such work are very limited. It is also recognized that ;
teachers, particularly those in developing countries are not well paid, and often i
i
augment their salaries with supporting jobs, thus placing severe limits on the "out-of- I
class hours" that are available for apparatus production. j
However, in designing equipment for production by students and teachers, two factors i
have been kept in mind. One, project work in apparatus development can be extremely
rewarding for students, bringing both students and teachers into close contact with the ■
realities of science, and relating science and technology in the simplest of ways. Two,
it is not difficult for cottage (or small scale) industries to adapt these designs to
their own requirements. The Guidebook should therefore not only be of value to students
and teachers, but also to cottage industries which may well be the major producers of
equipment for schools.
Although all the designs in the Guidebook have been tested under laboratory
conditions in the University of Maryland, they have not been tested in school situ-
ations nor produced and tested under local conditions in developing countries. It is
therefore recommended that the designs should be treated primarily as limited resource
materials to be subjected to trial and feedback. It is suggested that the first time
that an item is constructed it should be made precisely as described in the Guidebook,
since variations in the materials, or the dimensions of the materials, could alter the
characteristics of the apparatus. However, once this item has been tested the producer
is encouraged to make any number of modifications in the design, evaluating the new
products against the original.
Before producing new equipment in quantity, it is recommended that educators
with experience in the field of science education should be involved in determining
how best to make use of the Guidebook. They will wish to relate the apparatus to their
own curriculum requirements, and, where necessary, prepare relevant descriptions of
experiments which they recommend should be undertaken using the selected apparatus.
They will want to subject the experiments and related equipment to trials in school
situations. Only then will they consider large-scale production of apparatus from the
designs in the Gu idebook. At this stage educators will wish to control the quality of
apparatus production, to train teachers to make the best use of the new apparatus, and
to insure that adequate laboratory conditions are developed to permit full utilization
of the apparatus. Too often in the past apparatus has sat unused on many a classroom
shelf, simply because the teacher has been untrained in its usage, or the laboratory
facilities have been inadequate, or because the apparatus available did not appear to
fit the requirements of the existing curriculum. Such factors are best controlled by
educators in the field of science education in each country. Clearly the science
educator has a crucial role to play.
Apparatus development, like any aspect of curriculum development, should be
considered as a never ending process. This Guidebook is not presented as a finished
product, but as a part of this continuing process. There is no doubt that the designs
in this book could usefully be extended, descriptions of experiments utilizing the
apparatus could be added, and the designs themselves could be improved. No extravagant
claims are made concerning the Guidebook. It is simply hoped that it will contribute
to the continuing process of development.
-x-
TOOLS AND RAW MATERIALS
The raw materials required to make specific items of equipment are indicated at
the beqinninq of each item description. However, there are certain tools and materials
which are useful in any equipment construction workshop, and these are listed below.
Tools
Chisels, Wood
3, 6, 12, 24 mm
(i.e., 1/8", 1/4", 1/2", 1")
Cutters
Bench Shears: 3 mm (1/8") capacity
Glass Cutter
Knife
Razor Blades
Scissors: 200 mm(8")
Snips (Tinmans), Straiqht: 200 mm (8")
Snips (Tinmans), Curved: 200 mm (8")
Taps and Dies: 3 to 12 mm (1/8" to 1/2") set
Drills and Borers
Cork Borer Set
Countersink, 90'
Metal Drill Holder (Electrically Driven) , Capacity 6 mm (1/4")
Metal Drills: 0.5, 1, 2, 3, 4, 5, 6, 7 mm
(i 1/32" 1/16" 3/32" 1/8" 5/32", 3/16", 7/32", 1/4") set
Wood Brace with'Ratchei : 250'mm (10")
Wood Auqur, Bits: 6, 12, 18, 24 mm
(i.e., 1/4", 1/2", 3/4", 1")
Files, Double Cut
Flat: 100 mm, 200 mm (4", 8")
Round: 100 mm, 200 mm (4", 8")
Triangular: 100 mm (4")
Hammers
Ball Pern: 125, 250, (1/4, 1/2 lb)
Claw 250 g (1/2 lb)
Measuring Aids
Caliper, Inside
Caliper, Outside
Caliper, . Vernier (may replace above two items)
Dividers: 150 mm (6"), Toolmakers
Meter, Electrical (Multipurpose- volts, ohms, amps, etc.)
Meter Stick
Protractor
Scriber
Measuring Aids (Continued)
Set Square
Square, Carpenter's: 300 mm (12") blade
Spoke Shave: 18 mm (3/4")
Wood Smoothing Plane
Pliers
Combination: 150 mm (6")
Needle Nose: 150 mm (6")
Side Cutting: 150 mm (6")
Vise Grips
Saws, Metal
300 mm (12") blades
Saws, Wood
Back Saw: 200, 300 mm (8", 12")
Coping Saw: 200 mm (8")
Cross Cut: 600 mm (24")
Hand Rip: 600 mm (24")
Key Hole Saw: 200 mm ( 8 " )
Screw Drivers
100 mm (4") with 2 and 3 mm tips
150 mm (6") with 5 mm tip
200 mm (8") with 7 mm tip
Vises
Metal Bench Vise: 75 I1U1 (3")
Wood Bench Vise: 150 mm (6")
Miscellaneous
Asbestos Pads
Goggles, Glass
Oil Can: 1/2 liter pint)
Oil Stone, Double Faced
Punch, Center
Sandpaper and Carborundum Paper, Assorted grades
Soldering Iron: 60 watts, 100 watts
Raw Materials
Adhesives
All Purpose Cement (Elmers, Duco)
Epoxy Resin S Hardener (Araldite)
Rubber Cement (Rugy)
Wood Glue (Weldwood)
Cellophane Tape
Plastic Tape
Masking Tape
Electrical Materials
Bulbs with Holders: 1.2, 2.5, 6.2 volts
Dry Cells: 1.5, 6 volts
Electrical Wire: Cotton or Plastic covered
Fuse Wire: Assorted
Lamps: 50, 75, 100 watts
*Magnet Wire: #20, 22, 24, 26, 28, 30, 32, 34
Nichrome Wire: Assorted
Parallel Electrical Cording
Plugs
Switches
Glass and Plastic
Acrylic (Plastic) Sheets: 2 cm and 2.5 cm thick
Plates, Glass
Tubes, Glass: 3, 6 mm (1/8", 1/4") internal diameter
Hardware
Bolts and Nuts, Brass or Steel; 3 mm (1/8") diameter: 12, 24, 48 mm
(1/2", 1", 2") lengths
Nails: 12, t 7A mm (1/2", 1") lengths
Screws, Eye
Screws, Wood: 12, 18, 24, 26 mm (1/2", 3/4", 1", \ 1/2") lengths
Thumbtacks
Washers (Brass and Steel) : 6, 9 mm (1/4", 5/16") diameter
Wingnuts (Steel) : 5 mm(3/16")
Lumber
Boxwood (Packing Case Material)
Hardboard: 6 mm (1/4") thick
Kiln Dried Wood: 2.5 x 15 cm (1" x 6") cross section
1.2 x 15 cm (1/2" x 6") cross section
Plywood: 6, 12 mm (1/4", 1/2") thickness
Wood Dowels: 6, 12 mm (1/4", 1/2") thickness
* U. S. Standard Plate numbers are used in this book to indicate the gauge of
different wires. Where wires are referenced against other numbering systems
appropriate corrections should be made in determining the gauges of materials required.
The following comparison of gauges may be of interest:
Standard Diameter of #20 Wire
Brown & Sharp 0.08118
Birmingham or Stubs 0.089
Washburn & Moen 0.0884
Imperial or British Standard 0.0914
Stubs' Steel 0.409
U. S. Standard Plate 0.09525
Metal Sheets
Aluminum: 0.2, 0.4 mm (1/100", 1/64" ) thickness .
Brass: 0.4, 0.8 mm (1/64", 1/32") thickness .
Galvanized Iron: 0.4 mm (1/64") thickness.
Lead: 0.1mm (1/250") thickness .
Spring Steel, Packing Case Bands
Metal Tubes:
Aluminum, Brass, Copper: 6, 12 mm (1/4", 1/2") internal diameter .
Metal Wires
Aluminum: 3 mm (1/8") diameter
Coathanger: 2 mm (1/16") diameter
*Copper: #20 24
Galvanized Iron: 2 mm (1/16") diameter
*Steel: #20 26, 30.
Paint Materials
Paint Brushes
Paint Thinner
Varnish
Wood Filler
Miscellaneous
Aluminum Foil
Cardboard Sheeting
Containers (Plastic or Glass)
Corks (Rubber or Cork)
Grease
Hinges: Assorted
Machine Oil
Marbles
Mesh (Cotton, Nylon, Wire)
Modelling Clay (Plasticene)
Paper Clips
Pens: Felt (Marking Pens)
Pins and Needles
Rubber Bands
Soldering Lead
Soldering Paste
Spools
Steel Wool
Straws
String (Cord, Cotton, Nylon)
Styrofoam
Syringes: Assorted
Wax (Paraffin)
*See footnote on previous page.
I. GLASSWARE TECHNIQUES AND ACCESSORIES
Equipment made of glass or using glass components has applications in all branches
of science. This chapter includes some basic glass-working techniques that will be
necessary for constructing much of the equipment in this book.
These are presented in sections which describe the type of equipment needed, the
type of glass to use j and techniques for working with several forms of glass.
.J
A. BURNERS, TOOLS, AND EQUIPMENT
This section discusses burners that can be used in working glass, as well as
listing the tools and other items necessary for working with glass.
B. GLASS
This section describes the type of glass that works best with the burners listed
in section A.
C. SAFETY
Notes for safe handling and working of glass are given here.
P. 'PROCEDURES FOR GLASS TUBING AND RODS
Directions for working with glass tubing and solid rods are given in this section.
E. GLASS SHEET OPERATIONS
This section tells how to cut and drill glass sheets.
F. BOTTLE AND JAR TECHNIQUES
Much useful laboratory glassware can be made by using discarded bottles and jars.
This section includes directions for cutting and drilling these items.
G. STOPPERS
This section discusses types of stoppers and describes techniques for drilling
holes in them.
A. BURNERS, TOOLS, AND EQUIPMENT
Glass-working techniques described here are designated for use with Modified
Alcohol Burner (II/B2), and the Gas Burner (II/C2) . Of these, the gas burner, if
available, is most highly recommended.
The general items required for general glass-working techni'ques are as follows:
Glass Cutter
^
o
Triangular File
Round File
Set of Cork-borers
Pliers
Brick or Asbestos Pads
Rags or Pieces of Cloth
Clean rags, or pieces of cloth no smaller than about 10 cm x 10 cm.
String
Kerosene
Camphor
Ruler
Blotting Paper or Paper Towels
Emery Paper
Container of Sand
GLASS
There are many different types of glass, with different properties, depending upon
the chemical composition of the glass. Two very common types of glass that are dis-
cussed here are "soft glass" and "hard glass."
Soft Glass
This term includes a number of the oldest known and most common types of glass in
general use. Most bottles, jars, window glass, and much glass tubing and rods are
made of some type of soft glass. Such glass is used for items of simple design and
moderate thickness, that will not be subjected to very high temperatures.
One of the most important properties of soft glass, from the point of view of this
book, is that it can be softened in the heat of an air-gas flame. This is the type of
flame produced by the burners specified in section A. Also, soft glass has a wide
range of working temperatures, which makes it easy to work even after it has been
removed from flame.
Although it is easy to work, soft glass has some limitations and must be used with
care. An empty container of soft glass cannot be greatly heated, or it will crack.
I£however, such a container holds a liquid or powder, it can safely be heated,
slowly. Also, a soft glass container, with or without anything inside, must not be
suddenly cooled when hot or suddenly heated when it is cold. Otherwise, it will break.
Hard Glass
Hard glass has been developed during the twentieth century. Of a number of types
produced, "Pyrex" is one of the most common brand names., Most manufactured laboratory
glassware is now made of hard glass, which is harder stronger, more chemically inert,
and safer to use over a wider temperature range than soft glass.
Laboratory glassware made of hard glass is safer than soft glass. It can be
rapidly heated or cooled to greater temperature extremes without danger of breaking.
It does not scratch easily, and it does not break as easily as soft glass if struck or
dropped.
Although it is often manufactured into laboratory glassware, hard glass is not
generally made into the bottles and jars that are used for much of the apparatus
described in this book. Therefore, it is not as generally available as soft glass.
As tubing, rods, and sheets, it is usually more expensive than the same items made of
soft glass.
Hard glass's most important disadvantage here is that it must be worked in an
oxygen-enriched flame. The burners described in section A cannot heat hard glass hot
enough for working.
Therefore, only soft glass is suitable for use with the alcohol or gas burners
described. The techniques here listed have been tested using soft glass and the air-
gas flames produced by such burners.
Testing for Soft Glass
To determine whether a piece of glass is "hard glass" or "soft glass", heat it in
the flame of an alcohol or gas burner. Ifthe glass begins to glow and soften enough
to be easily worked, it is soft glass. If it does not soften, it is hard glass and
cannot be worked without specialized equipment.
■._i
C. SAFETY
Glass working, like most other laboratory procedures, carries a set of risks. By
arranging a safe work area and taking a few precautions, however, most such risks can
be avoided.
Sharp Edges and Points
There is always a danger of being cut by sharp points and edges of broken or cut
glass. Be careful of such edges and points, and try to handle the glass away from the
edges. Fire polish or smooth with emery paper any cut edges or points that are part
of a finished project. Keep such edges away from the mouth and eyes at all times, and
keep the work area clear of waste glass.
Burns
Hot glass looks just like cool glass! To avoid burns, allow heated glass to cool
before handling it. Rest it on bricks or asbestos pads, or in a container of sand.
Before picking up a piece of previously heated glass, touch it lightly with the finger-
tips to check that it is cool enough to handle. In cases where hot or warm glass must
be handled, protect the hands with a holder of several layers of cloth, or use holders
such as those described in the section on holders (IV) . Protect the body from burns
with clothing, an apron, overall, or laboratory coat.
Fire
Both the burner flame and hot glass can start a fire. Prevent this by keeping all
flamable material, such as paper or cloth away from the flame and any hot glass. Set
hot glass down on things that will not burn, such as bricks, asbestos pads, or sand.
To keep hair or clothing from being singed or igniting, tie back long hair, roll up
sleeves, and secure loose clothing close to the body. Inspect the burner, fittings,
tubing, and fuel supply each time the equipment is used to prevent leaks of fuel that
might lead to a fire. If any alcohol should spill, immediately put out the flame and
mop up the spill .
The container of sand mentioned for holding hot glass is also useful for fire con-
trol. If paper, cloth, or spilled alcohol should ignite, smother the fire by dumping
sand on it. If on the other hand, the gas burner system (II/Q]is used and a fire
develops, get away fast!
Eye Damage
To prevent eye damage, keep all sharp edges and points, all hot glass, and all
flames away from the eyes. Wear safety goggles or eye glasses to provide additional
protection for the eyes.
Gas Danger
If natural gas or bottled gas is used as fuel for the burner, a leak in the system
can release gas that is poisonous to breathe. To avoid this danger, inspect all pipes,
tubing, and fittings often.
L_
n
D. PROCEDURES FOR GLASS TUBING AND RODS
Dl. Cutting
a. Materials Required
Length of soft glass tubing or solid rod
Triangular file
Ruler
b. Procedure
£
Lay the tubing or rod flat on
the work surface and measure
the desired length. Make a
scratch on the glass at this
point by drawing one edge of
the file across the tube. Press
hard enough with the file to
make a deep scratch.
scratch
Moisten the scratch, then grasp
the glass firmly in both hands
with the thumbs on the side of
the tube opposite the scratch.
Apply pressure with the thumbs
while pulling out and down with
the hands until the tube or rod
snaps cleanly.
D2. Bending
a. Materials Required
Burner: wide-flame alcohol burner
or
wing tip with gas burner
Length of soft glass tubing or solid rod
Cooling surface: brick
or
asbestos pad
b . Procedure
Gravity Bending
S>
_i
With one hand, hold the tubing
or rod, just above the inner
cone of the flame. Rotate the
tubing to heat it evenly until
the free end droops under its
own weight.
■SZ:
*
Remove the glass from the
flame. It should bend to a
right angle. Allow it to cool.
Manual Bending
Install the wing tip on the gas
burner, and light the burner.
Hold each end of the tubing or
rod. Support the glass so that
it is level, with its middle in
the hottest part of the flame.
Turn the tubing or rod back and
forth by rotating the thumb and
first finger. Continue to heat
it evenly until it softens.
-10-
Bend Up
Bend Up
When the tubing or rod is soft,
remove it from the flame. Imme-
diately, bend the ends up until
the tubing or rod is bent at a
right angle (90 ' ) .
Rest the hot tubing or rod on a
brick or other cooling surface.
C. Notes
(i) If a wing tip is not available or if a standard alcohol burner is used,
the tubing or rod must be heated differently. Hold each end of the glass and
support it so that it is level with the middle just above the inner core of
flame. Rotate the tubing back
4 ■ c
A
v> A.
u^
and forth. At the same time,
move it to the left and right
so that about 0.3 cm of its
length of evenly heated. Con-
tinue to both rotate and move
the tubing or rod until the
heated section softens.
Remove from the flame and bend
it as described above.
(ii) With a little practice with glass tubing, you should be able to achieve a
bend in which the opening stays
Properly
Heated
Q_
i\
Under Heated
the same throughout the bend.
Overheating or underheating the
tubing, however, will produce
poor bends. Underheating causes
the tube to fold in at the bend.
Overheating causes the tube to
collapse at the bend.
d
over Heated
<~j
-11-
(iii) If a U-shaped bend is desired, first make one 90° bend as described above.
After allowing the glass to
cool, make another 90' bend
near the first one.
fl
J
-12-
D3 . Stretching
a. Materials Required
Burner: wide-flame alcohol burner
or
wing tip with gas burner
Length of soft glass tubing or rod
b. Procedure Hold the glass tubing or rod in
the flame. Turn it as it heats,
just as for making a bend.
< }
■*--~" ** ' Heat the glass evenly until it
<L
Pull Apart t" softens. When the tubing or
rod is soft, remove it from the
flame. Pull the ends apart
until the center has become
narrow and stretched about
25 - 30 cm.
> <
After the stretched part has
cooled, it can be cut as
required (I/Dl) . Carefully
fire polish the edges (I/D4) .
c. Notes
(i) Stretched glass tubing has many applications in laboratory glassware. For
example, the ends of the stretched tubing pictured above, with a narrow opening at
j. ^ one end, may be used as nozzles
or jets.
The very narrow section of the tubing, the stretched part, may be used as a capil-
fl =3 lary tube.
(ii) If a wing tip or wide-flame burner is not available, follow the procedure
given for heating a wide area of glass without the wing tip [I/D2, Note (i)] .
•13-
D4. Fire Polishing Tubing
a. Materials Reguired
Glass tubing with cut edge
Burner
Cooling surface
b. Procedure
Rough Edge
of Tubing
c. Notes
Hold the rough, cut end of the
glass tubing in the hottest
part of the flame, just above
the inner cone. Turn the
tubing constantly until the
edge glows red.
Remove the tubing from the
flame. Examine the heated end.
If it is now rounded smoothly,
rest the hot tubing on a brick,
asbestos pad, or sand to cool.
If the other end of the tubing
is also rough, repeat the fire
polishing procedure .
(i) Do not overheat the end of the tubing, or it will tend to close entirely.
(ii) Fire polish the ends of all glass tubing in use, as a safety measure.
(iii) Tubing with thick walls — for example, 0.5 cm (inside diameter) and larger —
must be annealed to prevent cracking. To do this, hold the end in the flame for
about one second, then remove from the flame for about one second. Repeat this
procedure eight or ten times, then hold the end in the flame, turning it con-
stantly until it is red hot. To cool thick-walled tubing slowly, remove it from
the flame, but hold the tubing near the flame for a few seconds. Gradually move
the hot end of the tubing further from the flame until it can be rested on the
brick or other cooling surface.
-14-
D5, Closing Tubinq_
a. Materials Required
Burner
Glass tubing
Cooling surface
b. Procedure
Narrow Tubing
Wide Tubing
-« ^
CE
D
When using tubing with a
diameter of less than 1.0 cm,
hold the end of the tubing in
the hottest part of the flame,
just as for fire polishing.
Turn the tubing constantly.
Continue heating until the end
closes .
When using tubing with a dia-
meter greater than 1.0 cm,
heat the tubing near one end,
rotating the tubing as it heats.
When the tubing is soft, pull
it apart.
Continue to heat and pull the
ends apart until the ends
separate and the pointed end
has closed.
-15-
._J
D6, Glass Blowing
a. Materials Required
Gas burner
Length of soft glass tubing
Cooling surface
b. Procedure
3)
o
c .Notes
Fire polish one end of the
tubing. Allow it to cool.
Close the_ other end by heating
in the flame. Heat the closed
end, rotating it constantly.
While continuing to heat and
rotate the tube, blow very
gently, in short, light puffs,
into the open end of the tube.
Just as the closed end of the
tube begins to swell and glow
pale red, remove it from the
flame. Blow strongly into the
tube, while rotating it, to
form a small round bulb.
(i) This procedure takes practice and patience to learn. It is helpful to
begin with the narrowest tubing available; 0.3 cm tubing, for example. A common
problem is blowing out the side of the bulb while the tubing is still in the flame.
(ii) A limiting factor in the size of tubing that can be used and the size of
the bulb that can be blown is the burner used. The gas generating system
(Il/tjimd burner (II/C2) are adequate to allow 0.3 cm and 0.5 cm tubing to be
blown into bulbs about 0.8 cm in diameter.
-16-
D7 . Making Rim in Tubing
a. Materials Reguired
Burner
Glass tubing
Triangular file
Brick, or asbestos pad
b. Procedure
Flattening
Push Down
Hold one end of the tubing in
the hottest part of the flame.
Turn it constantly until the
edge glows red. Remove the
tubing from the flame. Quickly
push the hot end evenly down
against the brick or asbestos
pad. A lip should form.
Allow the glass to cool.
Flaring
Heat one end of the tubing
until it is red hot. Remove
the tubing from the flame.
Hold the thin handle end of the
file inside the end. Press
gently outward on the file,
while turning the tube to form
a flared edge.
Allow the glass to cool.
-17-
,- 1
D8. Finishing Ends of Rods
a. Materials Required
Soft glass rods
Burner
Brick, or asbestos pad
Pliers
b. Procedure
Fire Polishinq_
o
Flattening,
Squeezing
Follow the procedure for fire
polishing glass tubing (I/D4) .
It will be necessary to heat
the end of the rod for a longer
period of time. The fire
polished end will have a small,
solid bulb. Holding the rod
in the flame for a longer time
will produce a larger bulb at
the end.
Allow the rod to cool.
Follow the procedure for
flattening glass tubing (I/D7)
to form a flat disc at the end.
Allow the rod to cool.
Heat one end of a rod as before.
When it is hot, remove it from
the flame. Compress about 1 cm
of the end of the rod between
the jaws of the pliers. A
flattened paddle-shaped end will
form.
Allow the rod to cool.
L
c. Notes
(±& useful stirring rod can be made with a rod of about 0.3 - 0.5 cm diameter,
15 - 20 cm long. Flatten one end and squeeze or fire polish the other.
t
-19-
GLASS SHEET OPERATIONS
El. Cutting
a. Materials Required
Glass cutter
Sheet of glass
(for example, a pane of window glass)
b. Procedure
Push Down
Lay the glass flat on bench
of table. Hold the ruler along
the line to be cut, with one
hand; and with the other hand,
draw the wheel of the glass
cutter on the glass along the
ruler. Press hard enough to
scratch the glass.
Place the underside of the
scratch exactly over the edge
of the table or bench. Press
down on both sides to break
the glass cleanly along the
scratch.
•20-
E2 . Drilling a Hole
a. Materials Required
Sheet of glass
Triangular file
Hammer
Turpentine
Camphor
b. Procedure
2ZX4-
Broken Corners
-Turpentine And
camphor
Take a little turpentine in a
bottle cap. Put a small amount
of camphor in it. Chip off the
end of the triangular file with
a hammer. This chipped end
has sharp corners.
Drop of
Turpentine
Camphor
Place the glass flat on a
table. Dip one of the sharp
corners of the broken file into
the turpentine-camphor mixture.
Press this corner of the file
down on the spot to be drilled.
Twist the file back and forth
to drill into the glass. Use
more turpentine-camphor as
needed and continue drilling
until the hole is complete.
-Zl-
c. Note s
(i) Drilling by hand is slow and may take ten or fifteen minutes.
(ii) A completed hole can be enlarged with the edge of the triangular file or a
round file, and the turpentine-camphor mixture.
(iii) After making the beginning hole on the surface of the glass, it is in fact
easier to use a hand drill with the triangular file as the bit. However, extreme
care must be taken. Do not push down on the drill at all, or the glass might
break. Let only the weight of the drill be the force on the glass.
(iv) Follow this same procedure to drill a hole in a glass bottle or jar.
-22-
F. BOTTLE AND JAR TECHNIQUES
Fl. Etching
(1 ) Etching Guide
a. Materials Reguired
Components
(1) Etching Guide
b. Construction
(1) Etching Guide
(A)
Qll I tems Required
1 Wood (A)
1 Wood (B)
Dimensions
Approximately 10 cm x
20 cm x 1 cm
Approximately 10 cm x
10 cm x 1 cm
Cut V-shaped notches into one
edge of a wooden board (A) .
Make the notches about 1 cm
deep and about 2 cm (or other
desired interval) apart. Then
secure the base (B) at right
angles to (A) with nails or glue
and screws.
c. Notes
(i) The etching guide is used in combination with a triangular file or glass
cutter to scratch a continuous line on a bottle or jar, prior to cutting. The
-23-
Cutting
Tool
bottle or jar is placed on the
stand and a glass cutter or
triangular file is placed in
a notch at the desired height.
The bottle is rotated, and
pressure is maintained against
it with the tool so that a
continuous scratch is scored
around it .
(ii) A second method for etching a bottle, jar, light bulb, etc. to be cut is
to wrap a strip of adhesive tape or paper around the glass as a guide. After the
line has been scratched completely around the glass, the tape is removed.
(iii) After the glass has been etched in either of these two fashions, it may be
cut using one of the technigues described in the following section.
-24-
F2. Cutting
Electrical Heating
(3) Wi
(2) Terminal
(1) Stand
a. Materials Required
Components
(1) Stand
(2) Terminal
(3) Wiring
b. Construction
(1) Stand
Qu
Items Required
l
Wood (A)
2
Wood (B)
2
Bolts (C)
4
Nuts (D)
1
Nichrome Wire (E)
^L^
Hole .
Insulated Copper Wire (F)
Dimensions
30 cm x 10 cm x 2 cm
25 cm x 4 cm x 2 cm
3 cm long, . 5 cm
diameter
. 5 cm
Size #24 (0.06 cm
diameter) , 34 cm long
Size #20 (0.08 cm
diameter) , 125 cm long
Drill a hole in one end of each
of the two uprights (B) . This
hole should be slightly smaller
in diameter than the bolts (C)
used for the terminals. Next,
nail or screw the uprights to
the base (A) .
-25-
(2) Terminal
Cut the heads off the two bolts
(C) , and put glue into the holes
in the uprights (B) . Screw the
bolts down into the hole,
leaving about 1.5 2 cm pro-
truding. Next, secure the
bolts by screwing on one nut (D)
until it is tight. Screw on
the second nut (D) loosely.
(3) Wiring
C. Notes
wrap one end of the #24 ni ch-
rome wire (E) around one bolt
(C) for one or two turns and do
the same with the other end.
Tighten the second nut (D) on
the terminals until the nich-
rome wire is firmly held.
There should be about a 5 cm
sag in the middle. Fasten the
copper wires (F) to each
terminal in the same manner.
Connect clips to these wires.
For power use a transformer
(PHYS/VII/A2) wired to a wall
outlet [Note (iii) ] , or a heavy-
duty battery.
(i) Prepare the jar, bottle, light bulb, etc., to be cut by etching a continuous
line around the glass (I/Fl) . Connect the cutter to a power supply until the
wire is hot, then place the etched line on the hot wire, Hold the glass in this
position until it cracks along the healed portion. Then rotate the glass to heat
another portion of the etched line. Continue this procedure until the crack has
-26-
circled the glass and the two sections separate.
(ii) The broken edges of the glass can be smoothed by rubbing them with wire
gauze or wet sandpaper (emery paper) .
(iii) If the wire cutter is used with a wall outlet (120 volt) then a transformer
must be employed to bring the voltage down to 12 volts, 3 amps. The cutter can
also be used with a standard 12 volt automobile battery. However, using a
battery reguires more time for heating the etched line, since the wire does
not get as hot .
-27-
Strinq Heating
a. Materials Required
Bottle, jar, or light bulb
String
Container of cold water
Alcohol, kerosene, or turpentine
Tape or paper
Glass cutter or triangular file
b. Procedure
-Scratch
"String
Wet Paper Cooling
a. Materials Reguired
Bottle, jar or light bulb
Alcohol or gas burner, or candle
Triangular file or glass cutter
Blotting paper or wrapping paper
String
Container of cold water
Prepare the bottle or jar as
described in I/Fl above. After
the paper or tape guide has been
removed, tie a piece of string
or cord which has been soaked
in a flammable liquid around
the bottle about . 5 cm below
the scratch. Liqht the string
with a match, and as soon as
the flame dies down, pour cold
water on the bottle. The sud-
den change from hot to cold will
break the bottle along the
scratch. This process may have
to be repeated to break thick
glass. Smooth the cut edge of
the glass as described in
Note (ii) above.
-28-
b. Procedure
Scratch
Paper
Wind a strip of blotting paper,
paper towel, or wrapping paper
about 5 cm wide around the
bottle at one side of the line
to be cut. Wrap the paper at
least 0.5 cm thick and then tie
the paper with string or rubber
bands. With the file or glass
cutter, scratch a line com-
pletely around the bottle at
the top edge of the paper. Put
the bottie into cold water
until the paper is soaked
(about five minutes) . Remove
the bottle from the water, and
rotate it in a horizontal posi-
tion, with the scratch on the
glass just above a small, fine
flame. Continue this for four
or five minutes. If the
bottle has not dropped apart,
put the bottle vertically into
the water. The bottle should
break into two parts along the
scratch. If it does not,
repeat the heating and cooling
until it does. It is crucial
that the flame be very small so
as to heat a minimum of glass
on either side of the scratch.
c. Notes
(i) To drill a hole in a glass bottle or jar, follow the procedure outlined
for drilling in a glass sheet (I/E2) .
-29-
G. STOPPERS
Stoppers for use in scientific apparatus are commonly manufactured of either cork
or hard rubber.
Rubber Stoppers
Rubber stoppers are more durable for general use than cork stoppers. They are
available in standardized sizes, and are manufactured with no holes as well as with
one, two or three holes. Although they tend to react with organic solvents like
gasoline, they provide an excellent seal in most cases and can even be sterilized.
(BI0/VII/A2) . If a stopper with holes is specified in the directions for a piece of
apparatus, use rubber stoppers with pre-drilled holes if at all possible. If it
becomes necessary to drill a hole or holes in a rubber stopper, consult the notes
following the discussions of boring and drilling holes in cork stoppers(I/Gl and
G2) .
Cork Stoppers
Cork stoppers, while generally less expensive than those made of rubber, are not
as suitable for general use. They tend to lose their shape after long use, are not
available with holes pre-drilled, tend to absorb reagents, and cannot be adeguately
sterilized. Should it be necessary to bore a hole or holes in a cork stopper for the
insertion of glass tubing, one of the following methods may be employed.
Gl, Cork Boring
a. Materials Required
Cork stopper
Set of hand cork borers
b. Procedure
■* Cleaning
Rod
ts— >>. , Cutting
\~s* Edge
If a set of hand cork borers in
graduated sizes is available
from a scientific supply house,
choose a cork borer of the same
or slightly smaller diameter as
the glass tubing that is to go
through the cork.
The cork borer set generally is
supplied with a rod to clean
pieces of cork out of the
borer. Soften the cork by
wrapping it in a piece of
paper and rolling it gently on
the floor under your foot.
With one hand, hold the cork
firmly on the table or bench,
wide end up. With the other
hand, place the cutting edge of
the cork borer in the center of
the cork. Then with a gentle
twisting motion on the cork
borer, bore into the cork until
the tool is about halfway
through the cork.
It is not necessary to push hard;
but twist gently with light
pressure. Remove the cork borer
from the cork and push out small
pieces of cork inside it with
the cleaning rod.
Turn the cork over and repeat
this process until there is a
hole through the cork.
-31-
c. Notes
(i) Iftwo holes are desired, the first must be bored near one edge of the cork
in the manner described above.
The second hole is then bored
in the same way. A guide line,
drawn around the middle of
the cork, is helpful in deter-
mining the positions of the
two holes.
(Ii) This method is suitable for boring holes in rubber stoppers. However, the
stopper as well as the end of the boring tool should be lubricated with glycerine.
-32-
G2. Cork Drilling
a. Materials Required
Cork stopper
Round file
Cloth, or wooden handle
Burner
Brick or asbestos pad
b. Procedure
Soften the cork as described in
I/Gl above. Hold the cork,
wrapped in cloth or clamped in
pliers, securely against the
brick or asbestos pad with one
hand. Hold the file, wrapped
in cloth or in a wooden handle,
by its four-sided end in the
other hand. Heat the round end
of the file in the burner flame.
Remove the file from the flame
when it glows red hot, and push
it gently into the center of the
cork. Push it only about half-
way through the cork, then
remove it .
Turn the cork over, reheat the
file, and make another hole to
meet the first one.
Allow the file to cool, then
enlarge the hole to the desired
size by gentle filing.
c. Notes
Care must be taken not to overheat the file, or it may set the cork on fire.
Should this happen, blow the flame out quickly.
(ii) Two holes can also be made through the cork with this method.
(iii) Very small holes can be made in corks in the same manner by using heated
wire.
-33-
(iv) If a hand drill or electric drill is available, holes can easily be bored
by using either a regular drill bit or the round file as the drill bit, The cork
must be rigidly held in a vise. For an accurate hole, just as with the other
methods of drilling, a hole should be drilled halfway through the cork from each
side, to meet in the center of the cork.
(v) It is possible to drill holes in rubber stoppers with a hand drill or
electric drill, but the hot file method will not work in rubber stoppers.
G3 . Inserting Glass Tubing Through a Stopper
a. Materials Required
Glass tubing
Burner
One-hole cork or rubber stopper
Cloth
Glycerine
b. Procedure
Hold Here
Fire polish the end of the tube
that is to go into the stopper.
Allow it to cool. Hold the
tubing about 2 - 3 cm from the
fire-polished end in one hand.
Lubricate this end of the tube
with glycerine. Hold the
stopper in the other hand.
Gently and carefully push the
tube into the stopper with a
twisting motion. Do not use too
much force or the tube will snap.
When pushing a piece of bent
tubing into a stopper, always
hold the tube between the bend
and the stopper. Do not push on
the bend; it is weak and will
break easily.
c. Notes
(i) This is a technigue that, if improperly done, can be quite dangerous.
When done correctly, however, it is quite safe.
-34-
1 1 . BURNERS
These have been grouped according to the type of fuel used.
A. SOLID FUEL BURNERS
These are the simplest burners to make, and include candles as well as charcoal
burners .
B. LIQUID FUEL BURNERS
These include several types of alcohol burners.
C. GAS BURNERS AND SYSTEMS
These are functional items, providing the cleanest, most intense heat. However,
they are somewhat more sophisticated for production purposes,
-35-
A. SOLID FUEL BURNERS
Al . Candle Burner
(1 ) Container
(2) h
eat Source
a. Materials Required
Components
(1) Container
(2) Heat Source
b. Construction
(1) Container
(2) Heat Source
c. Notes
Qll I tems Required
1 Shallow Tin Can (A)
3 Household Candles (B)
Dimensions
5 cm diameter or
larger
Varies
Select a tin can (A) with low
sides .
Melt the wax at the base of the
candles (B) and place them at
equal intervals within the con-
tainer.
(i) The intensity of the heat produced may be increased by increasing the
number of candles, but the total intensity is low.
(ii) The efficiency of a candle burner may be improved by collecting all the wax
that melts into the container and using it again with new wicks made from soft
string.
(iii) The candle flames tend to deposit soot on the surface of whatever is being
heated.
-36-
A2. Charcoal Burner *
(1) Can
t '
i
a. Materials Required
Components
(1) Can
b. Construction
(1) Can
Qli I tems Required
1 Empty Metal Can (A)
Bend Up
Triangles
■Cut Here
Dimensions
10 cm diameter or
larger
Remove top from can (A) . Approx-
imately 4 cm from the bottom of
the can, mark off triangular
windows all around.
With shears, cut along the
sloping sides of each triangle
to make the windows . Do not cut
along the base line (horizontal
edge) of the triangle.
Bend the triangles up to form a
tray.
*Adaptedfrom UNESCO, Source Book for Science Teaching_ , (Paris: UNESCO, 1967),
pp 34-35.
-37-
c. Notes
(i) The holes permit air to circulate freely to the burning charcoal.
(ii) Comments from users of the charcoal burners indicate that they are hard to
start. Also, once started, they present a considerable fire and carbon monoxide
risk.
Bl, Simple Alcohol Burner
-3a-
LIQUID FUEL BURNERS
a. Materials Required
Components
(1) Fuel Container
(2) Lid
(3) Wick
b. Construction
(1) Fuel Container
(2) Lid
(3) Wick
Qu I tems Required
1 Glass or Metal
Container (A)
1 Screw Top (B)
1 Soft Cotton Fiber
Cord (C)
Dimensions
150-200 ml, approxi-
mate capacity
To fit fuel container
Long enough to extend
to bottom of con-
tainer and to cover it.
Make the fuel container from a
glass or metal container (A)
with a screw-on metal lid (B) .
Select a container with a wide
base to insure stability.
Punch a hole in the lid (B) with
a nail, making it as round and
smooth as possible, with a
diameter smaller than that of
the wick to be used.
Select a piece of cord (C) with
soft cotton fibers. The wick
should protrude 0.5 cm above
the surface of the lid.
c. Notes
(i) If a hotter, broader flame is required, punch two holes in the lid and use
two wicks to produce a single, broad flame.
-39-
(ii) The wick should be soaked in alcohol before lighting the burner.
(iii) Methyl alcohol or denatured ethyl alcohol is the usual fuel used in the
burner. Kerosene may also be used, but it tends to produce a smoky flame which
blackens heated objects.
(iv) Important: Use a stable container,
burner will tip over easily.
Otherwise, there is danger that the
(v) If the burner is used for prolonged periods, overheating of the container,
with build-up of internal pressure, is possible.
(vi) Make certain that the wick fits tightly into the hole in the lid. Other-
wise, it is possible for the flame to climb down the wick into the container.
(vii) A user of alcohol burners notes that those made from 35 mm film cans have
several advantages over larger ones made from glass containers. First, they are
unbreakable. Second, if the
inside is filled with cotton
wadding (cotton wool) they are
unspillable if knocked over.
Also, these small film cans
hold only enough for immediate
use, so that evaporation losses
are not serious .
Film Can
-4o-
B2 . Modified Alcohol Burner
(6) Cap
(5) Wick
„(4) Heat
Barrier
(3) Wick
Holder
(2) Fuel
Container
( 1) Base
a. Materials Required
Components QU Items Required
(1) Base 1 Wooden Platform (A)
Metal Lid (B)
Dimensions
Approximately 10 cm
diameter (round) , or
approximately 10 cm x
10 cm (square)
To fit fuel container
bottom
(2) Fuel Container
(3) Wick Holder
(4) Heat Barrier
(5) Wick
(6) Cap
1 Glass or Metal
Container (C)
1 Metal Lid (D)
Metal Tube (e)
1 Metal Disc (f)
1 Cord (G)
1 Ball Point Pen Top or
Metal Tube (H)
100-200 ml capacity
To fit fuel container
top (C)
Approximately 4 cm
long, 0.7 cm or 0.8 cm
diameter
5 cm diameter or
larger
Approximately 10 cm
long, 0.5 cm or more
in diameter
To fit wick holder
-41-
b. Construction
(1) Base
Lid (B)
Nail
Base (A)
Nail the metal lid (B) (with a
diameter equal to that of the
fuel container) to the round or
square wooden base (B) .
(2) Fuel Container
(3) Wick Holder
(CD
Select a qlass or metal con-
tainer (C) with a screw-on lid
(D).
Make the wick holder from a
metal tube (E) about 4 cm lonq
x 0.7 or 0.8 cm internal
diameter, or roll a piece of
sheet metal (4 cm x 2.5 cm)
into a tube.
(4) Heat Barrier
Seams
Seam
Drill a hole in the fuel con-
tainer lid (D) large enough to
allow insertion of the wick
holder. Insert the wick holder
so that it penetrates about
1 cm into the container. Solder
the seam along the tube and
between the tube and the lid.
Cut the metal disc (F) from
metal sheeting, or use a tin can
top. The disc should be
slightly larger than the fuel
container lid (D) .
Drill a hole in the center of
the disc large enough to allow
insertion of the wick holder
(E) . Insert the wick holder so
-42-
(5) Wick
(6) Cap
that about 1.0- 1 . 5 cm pro-
trudes above the disc. Solder
the seam between the heat
barrier and wick holder.
Make the wick from a piece of
cord (G) or rope with soft
cotton fibers. Insert the wick
into the wick holder. Trim
the wick with scissors so that
about 0.4 - 0.5 cm protrudes
above the top of the wick
holder.
Use a ball point pen top (H) as
a cap or make a metal cap large
enough to fit snugly over the
wick holder when the burner is
not in use. The cap prevents
evaporation of the alcohol.
c. Notes
(i) The design of this burner overcomes the major hazards of the simple alcohol
burner (I I/Bl) .
(ii) This 'design can be modified to produce a wide flame that is particularly
useful for working with glass. All parts of the design are the same, except for
the shape of the wick, wick holder, and cap.
For the wick holder, cut a piece of metal sheeting about 5 cm x 4 cm. Bend
it into a flat tube about 2 cm wide and 0.5 cm deep. Solder the seam. Install
this wick holder in the fuel container lid and heat barrier just as in the previous
design. For the wick, use flat cotton webbing about 2 cm wide and 10 cm long, or
braid (plait) a flat wick from
6) Gap
(5) Wick
\4) Heat Barrier
(3) Wick Holder
(2) Fuel
Container
six to ten strands of cotton
cord or string. Make a cap from
metal sheeting to fit snugly
over the wick holder when the
burner is not in use,
(1) Base
-43-
C. GAS BURNERS AND SYSTEMS
CI. Fuel System for Gas Burner *
(3) Fuel Unit
(1) Pressure Unit
(6) Connecting
Tubing
(5) Burner
a. Materials Reguired
Components
(1) Pressure Unit
(2) Clamp
(3) Fuel Unit
Qll I tems Required
1 Metal Drum (A)
1 Metal Drum (B)
3 Wood (C)
3 Bolts (D)
1-Hole Stopper (E)
Glass Tubing (F)
Container and Sand (G)
Screw Clamp (H)
Metal Can (I)
2-Hole Rubber Stopper (J)
Dimensions
Approximately 2 6
liter capacity
Approximately 16
liter capacity
3 cm x 2 cm x 65 cm
0.5 cm diameter,
4 cm long
Approximately 2 . 5 cm
diameter (large end)
. 5-0 . 7 cm diameter,
10 cm long
Approximately 6 kg
IV/A5
4 liter capacity,
approximately
To fit opening in can
*Adapted from C. S. Rao (Editor), Science Teachers' Handbook, ( Hyderabad, India:
American Peace Corps, 1968), pp 140-141.
-44-
(4) Safety Tank I
1
1
1
(5) Burner 1
(6) Connecting Tube 3
b. Construction
(1) Pressure Unit
Glass Tubing (K)
Glass Tubing (L)
Narrow-neck Bottle (M)
2-Hole Rubber Stopper (N)
Glass Tubing (0)
Glass Tubing (P)
Gas Burner (Q)
Plastic or Rubber Tubing
(R)
. 5 cm diameter, 10 cm
longer than height
of can
. 5 cm diameter, 10 cm
long
500 ml capacity,
approximately
To fit bottle
. 5 cm diameter, 10 cm
longer than height of
bottle
. 5 cm diameter, 10 cm
long
II/C2
Approximately 1 cm
diameter, and approxi-
mately 1 meter long
Wood (C)
Bolts (D)
Drum (A)
Select two metal drums (A,B) of
approximately the same depths,
but different diameters, so
that one drum (B) will fit
inside the other (A) . Each drum
should have one end open. Bolt
the three pieces of wood (C)
to the larger drum (A) with the
bolts (D) so that the space
between them is just sufficient
to allow the smaller drum (B) to
slide down easily between them.
-45-
Sand Can(G)
Glass
Tube (F)
Stopper (E)
-Drum (B)
Drum (A)
Use an alcohol lamp to make a
90' bend in the middle of the
glass tubing (F), or cut a
shorter piece of straight tubing.
Fit the glass tube into the
stopper (E) . Bore a hole near
one side in the bottom of the
smaller drum (B) . Insert the
stopper into this hole.
Fill the larger drum (A) with
water egual to the volume of
the smaller drum.
Fit the smaller drum, open side
down, between the wooden up-
rights of the larger drum.
Push down on the upper (air)
drum (B) . It should slide down
into the lower drum (A) . Air
should be felt escaping from the
glass tubing (F) .
Place a can or bucket filled
with sand (G) on the air drum,
as a weight .
(2) Clamp
Use the screw-type clamp (H) or
any standard screw-type clamp
to control the air pressure
from the fuel tank.
-46-
(3) Fuel Unit
Glass
Tube (K)
Glass
Tube (L)
2-Hole
Stopper (J
Metal
Can (I)
Gasoline
Fuel Unit
(Cross-section)
(4) Safety Tank
Stopper *-
(N)
Glass
Tube (0)
Glass
Tube (P)
Bottle (M)
Make the fuel container from a
metal drum (I) or can with a
single outlet, rather than a
lid. Fit the drum with a two-
hole rubber stopper (J) .
Make a 90' bend about 5 cm from
one end of the longer piece of
glass tubing (K) , or use a
slightly shorter piece of
straight tubing.
Make a 90" bend in the middle
of the short piece of glass
tubing (L) .
Insert both pieces of tubing
into the stopper as illustrated.
Fill the can about 3/4 full of
gasoline (petrol) .
Select a glass or metal con-
tainer (M) with a narrow neck.
Fit the container with the
two-hole rubber stopper (N) .
Bend both, pieces of glass
tubing (0,P) as described above,
and insert each into the stopper
as illustrated.
Fill this container about 1/3
full of water.
(5) Burner
(6) Connecting Tubing
Construct a Bunsen burner (Q)
as described in the next sec-
tion (II/C2) .
Use flexible tubing (R) (rubber
or plastic) to connect the
-47-
apparatus as illustrated.
Connect the tubing from the
Pressure Unit (1) with the long
glass tube of the Fuel Unit (3) .
Connect the tubing from the
short glass tube of the Fuel
Unit (3) with the long glass
tube of the Safety Tank (4) .
Attach the connecting tubing
from the short glass tube of
the Safety Tank (4) to the
Bunsen burner (5) . Take care
to see that the tubing is not
kinked anywhere .
When all components are
assembled and correctly con-
nected, remove the weight and
stopper from the upper (air)
drum. Lift the drum until its
lower edge 3s just below the
water level in the lower drum.
Replace the stopper and check
to see that it is tight, and
replace the weight on top of
the drum.
c. Notes
(i) As the air drum sinks into the water of the lower drum under its own weight
and the pressure of the weight on top, the air thus displaced is driven into the
fuel drum and bubbles up through the petrol. The petrol evaporates as the air
passes through it, and the air-gas mixture is driven through the water in the
safety tank to the burner.
(ii) This system is potentially dangerous because the petrol-air mixture present
from the fuel tank is an explosive mixture, but several safety precautions have
been incorporated into the design.
The greatest safety factor is the needle valve in the burner; even when the
burner occasionally "backfires" (the flame jumps down from the end of the burner
tube to the needle opening) the flame is very unlikely to move back through the
needle's narrow opening. In the unlikely event that a flame should move back down
48-
the tubing, the safety tank prevents it from reaching the fuel drum. As a further
safety measure in the safety tank, the stopper should be snug, but not jammed
tightly into the neck of the container. Thus, should the flame move back into the
safety tank, it will be more likely to blow the stopper out of the tank than to
blow the tank apart.
Despite the built-in safety precautions, however, feedback comments suggest
extreme care in the use of this system.
(iii) In the system described here, a glass bottle, encased in a cage of wire
mesh for additional safety, was used as a water tank. This made it possible to
observe the rate of bubbles in the water, an indicator of the pressure in the
system. A fairly rapid rate of bubbles, about 100 or more per minute, was neces-
sary to produce a burner flame 3 - 4 cm high. It is recommended, however, that
once the bubbling rate is established, a metal safety tank of similar size be
substituted for the glass bottle.
(iv) A weight of approximately 5.5 kg on an air drum with an area of 4 90 cm2
(diameter 25 cm) provided 11 g/cm2 pressure to run the Bunsen burner described in
the following section (II/C2) for about a half-hour.
(v) The system and dimensions described here constitute a small, laboratory
version suitable for running one Bunsen burner.
To Fuel
Unit
For a larger system, the same
components and principles apply,
but experimentation on the
details of construction will be
necessary. For example, a
larger pressure system, with a
large, heavy oil drum for the
upper drum would provide pres-
sure for a longer period of
time and might not reguire a
weight on top. An air pump
could be added to fill the drum
with air without lifting it.
Air Pump
-49-
C2. Gas Burner
1) Burner Tube
(2) Air Control Sleeve
(3) Gas Valve
(4) Base
(5) Gas Tube
a. Materials Required
Component s
(1) Burner Tube
(2) Air Control
Sleeve
(3) Gas Valve
(4) Base
(5) Gas Tubing
Qll Items Required
1 Copper Tubing (A)
1 Metal Sheet (B)
1 Hypodermic Needle (C)
1 Adhesive Tape or
Electrical Tape (D)
1 Wooden Block (E)
2 Wooden Block (F)
1 Rubber or Plastic
Tubing (G)
Metal Tube (H)
Dimensions
10.5 cm long,
1 cm diameter
3 cm x 3.5 cm
18 gauge (0.125 cm
outside diameter)
Approximately 1 cm
wide, 15-30 cm long
10 cm x 10 cm x 2 cm
10 cm x 5 cm x 2 cm
Approximately 15-20 cm
long, approximately
0.6 cm internal
diameter
3 cm long, 1 cm
diameter
*Adapted from C. S. Rao (Editor), Science Teachers' Handbook, (Hyderabad, India:
American Peace Corps, 1968), pp 138, 141.
■50-
b. Construction
(1) Burner Tube
^~D
Air Holes
(2) Air Control Sleeve
Metal
Sheet (B)
(3) Gas Valve
Drill two holes on opposite
sides of the copper tube (A)
about 2 - 2 . 5 cm from one end.
Enlarge the holes to an oval
shape, about 1 cm long x 0.6 cm
wide .
Lay the metal sheet (B) flat on
a table. Lay the burner tube
on it with the end of the tube
with the holes in it about 1.0
cm from the 3 . 5 cm edge.
Actually, the holes themselves
should be 1.0 cm from the 3.5
cm edge.
Use a pencil to trace the out-
line of one of the holes in the
tube onto the metal sheet. Cut
this hole out. lineWrap the metal
sheet around the burner tube
until it forms a cylinder.
Align the hole in the metal
sheet with one of those in the
tube. lineTrace the outline of the
other hole in the tube onto the
metal sheet. Remove the metal
sheet, and cut out the second
hole.
Reroll the air control sleeve
and place it in position on the
burner tube.
Cut the top off the hypodermic
needle (C) so that about 1 cm
of the needle remains. File the
linecut end of the needle open.
Needle
Base
-51-
pn
Q
n
Burner
' Tube
_Air Control
Sleeve
_Needle (C)
Base with
" Tape (D)
Wrap the adhesive tape (D) or
electrical tape around the
needle holder until the base of
the needle will fit tightly into
the bottom of the burner tube.
The open end of the needle
should be near the middle of
the air holes.
Side View
(4) Base
Wood (E)
Drill a hole approximately 1.2
cm in diameter in the center of
the square piece of wood (E) .
Enlarge the hole with a file to
tightly hold the burner tube
and gas tubing in place.
Nail the two rectangular pieces
of wood (F) to the square to
form the sides of the base.
Wood
(5) Gas Tubing
Rubber
Tube (G)
Metal
Tube (H)
Connect one end of the plastic
or rubber tubing (G) to the
bottom of the burner tube.
Then push the burner tube
through the hole in the top of
the base. It should fit snugly
in place and should not wobble.
Pass the other end of the gas
tubing through one open side of
the base. Ins ert the small
metal tube (H) into the open end
of the gas tub i ng.
Connect tubing from the gas
supply to this metal tube.
-52-
c. Notes
(i) This burner has been tested with both commercially supplied natural gas
and with the gas generating system described in the previous section II/C1.
(ii) When the burner is lit, the air control sleeve can be used to control the
nature and intensity of the flame. The sleeve is closed when its holes and the
holes in the burner tube. are not Mned up with each other. No air enters the
burner tube. The flame is smoky, yellow, and glowing. It gives little heat. The
absence of air prevents the gas from being completely burned.
When the sleeve is turned so that its holes and those of the burner tube
are partly lined up, some air enters the burner tube. The flame is almost color-
less, and does not glow. It is quite hot. The gas is more completely burned in
this flame because of the presence of some air.
When the holes of the air control sleeve completely match those in the
burner tube, the maximum amount of air enters the burner tube.
This produces a very hot, roaring flame with a bright blue center cone.
The gas is completely .burned, producing the hottest flame, because there is
plenty of air entering the burner tube.
Purplish Cone - hot part of the flame, called the
I 'l l i ii
0X1 01 Zing Tlame . Combustion of the gas is most complete.
Hottest part of the flame just above the inner blue
cone of flame.
cone not as hot as the outer cone because there
is insufficient oxygen mixed with the gas to completely
burn it. Called the reducing flame because it can take
oxygen away from some oxides.
Dark cone
not a flame at all. It is filled with a
mixture of unburned gas and air coming from the barrel.
Use a blue flame, about 4 cm high, for glass-working operations and most other
heating operations . Adjust the gas supply and air control sleeve of the burner
to produce a quiet blue flame with distinct cones.
(iii) In use this burner produced an excellent flame suitable for working soft
glass and for blowing small bulbs in 0.3 cm and 0.5 cm soft glass tubing. However,
the burner tube tended to heat up after a few minutes use. The larger diameter
burner, of slightly more complex design, avoids this difficulty to some extent.
(iv) If a larger diameter tube (e.g., 1.5 cm diameter) is used for the burner
tube, several alterations must be made to the design of the burner. First, a
larger diameter syringe needle is needed (16 gauge, 0.15 cm outside diameter), and
-53-
it must be cut off shorter, i.e., . 5 cm rather than 1.0. Secondly, the end of
the burner tube must be flattened slightly to restrict the flow of air/gas mixture
through it. Thirdly, the connection between burner tube, gas valve, and gas tube
must be altered. One way in which this can be done is to drill a hole 1.0 cm in
diameter through a cork.
Tj ^urn er Tube
If (Flattened
Needle
Base
Metal
Tube
Cross Section
Enlarge the hole at one end to
1 . 5 cm diameter, and 1 . 5 cm
deep. Insert a 1.0 cm diameter
piece of metal tubing through
the hole and place a short
(1.0 cm) piece of rubber tubing
on the end of it. Insert the
needle into the rubber tube
(the base may have to be built
up with tape) . Insert the
burner tube into the enlarged
hole in the cork. Make certain
the fit is tight. Finally,
insert the cork into the hole
in the base, put the air control
sleeve in place, and attach the
gas tubing.
If, when this burner is in use,
the flame should tend to blow itself out because the tube opening is too wide,
decrease it further by pinching with pliers.
(v) It must be noted that various components of the burner design are dependent
on the diameter of the burner tube. These include burner tube length, size of
the air holes, gauge and length of the needle, width at the top of the tube, and
various connecting devices such as metal and rubber or plastic tubing. For
example, if the diameter of the burner tube is increased, the diameter of the
needle used and the length of the tube must also be increased, but the size of the
opening at the top of the tube must be decreased. Therefore, if tubing of a size
different from those described here is used, experimentation with the other com-
ponents will be necessary in order to construct a working Bunsen burner.
-54-
13. Wing Tip
(1) Wing Tip
a. Materials Required
Components
(1) Wing Tip
QU I tems Required
1 Metal Sheet (A)
1 Metal Sheet (B)
Dimensions
6 cm x 4 cm
6 cm x 4 cm
b. Procedure
(1) Wing Tip
0.8
\ \L
4
r|
xVr
1
' /■
\ N
\ \
\ \
\ \
\ \
2
/ /
/ /
/ /
/ Metal
Sheet (A)
1
1 1.
i
V,
1.0
JL
U-4.
< »l
of Cii
0.5
y
X 0.5
■cumf erence
of I
3urner
Tube
Measure the circumference of
the burner tube. Draw and cut
out a paper pattern as
illustrated. Cut one piece of
this pattern from the metal
sheeting (A) . Cut on the
solid lines. Bend on the dotted
lines .
/ / Metal
/ / Sheet (B)
Cut another piece from the
metal sheeting (B) , but trim
the flaps on the wing to 0.4 cm.
Cut on the solid lines. Bend
on the dotted lines.
-55-
Metal (A)
Metal (B)
Burner Tube
Bend the wing flaps on piece
(B) at 90°. Bend the wing
flaps of piece (A) around the
outside of the flaps on (B) .
Pinch the flaps on (A) to hold
(B) in place.
Place the wing tip on the
burner tube, such that the
wing extends above the burner
tube.
Bend the support strip flaps of
(B) and (A) to fit snugly
around the burner tube. Small
holes left at the corners of
the flaps will not affect the
wing tip's performance.
c. Notes
(i) The wing tip is an accessory used with the gas burner when a wide flame is
desired. It is especially useful for working with glass.
-56-
III MEASURING APPARATUS
A. DEMONSTRATION DEVICES
These devices demonstrate thermal expansion of liquids and solids,
B. VOLUMETRIC MEASURES
These are all measures of liquid volume and ranqe from sinqle volume measures
like volumetric flasks to multiple measures such as measuring cylinder. Also included
under this heading is the specific gravity bottle.
-57-
A. DEMONSTRATION DEVICES
Al . Demonstration Thermometer
"(1) Thermometer
a. Materials Required
Components
( 1 )Thermometer
b. Construction
(1) Thermometer
Qu I tems Required
1 Pill Bottle (A)
1 Pill Bottle Cap (B)
1 Glass Tubing (C)
Dimensions
7 cm high, 3 cm
diameter
To fit pill bottle (A)
25 cm long, . 5 cm
outside diameter,
. 3 cm inside
diameter
Make a hole in the pill bottle
cap (B) (or a suitably sized
cork) through which the glass
tubing (C) is inserted.
Be certain the seal is airtight
(it may be necessary to use
glue to insure an airtight seal)
Fill the bottle (A) completely
with water or other liquid.
Force the cap or cork down onto
the mouth of the bottle so that
some liquid is forced up into
the tube and the rest of the
excess liquid spills over the
side of the bottle where it is
wiped away. Some liquid must
rise up far enough into the
tube so that it can be seen.
c. Notes
(i) This thermometer is used simply to demonstrate the expansion of a liquid
as it is used in standard thermometers. Putting the demonstration thermometer
into a 60°C water bath will cause the level of the water in the tube to rise about
2 cm.
(ii) Be certain to eliminate all air bubbles from the bottle unless it is
desirable to show the effect of having air trapped in the bottle.
A2. Bi-Metal Strip
-59-
(2) Handle
(1) Bi-metal Strip
a. Materials Required
Components Qu I tems Required
(1) Bi-metal Strip 1 Steel Strapping (A)
1 Aluminum Sheet (B)
9 Nails (C)
(2) Handle
1 Wood (D)
Dimensions
20 cm x 1.2 cm x
0.8 cm
20 cm x 1.2 cm x
0.6 cm
#4 d (0.2 cm diameter
with large heads)
1 . 5 cm x 2 . cm x
10 cm
b. Construction
(1) Bi-metal Strip
Y
20
eoooeoo o o
_i i_
/
Metal Strip (A,B)
Cut Here
* — J Nail (C)
0.5
Hammer This
r End Down
jL
Nail Head
Side View
Hold the two pieces of metal
(A,B) tightly together, and
drill nine holes through both
at 2 cm intervals beginning
1 . cm from one end. These
holes must be very slightly
larger in diameter than the
nails (C) used.
Cut the head off each nail (C)
with a hacksaw, chisel, or tin
snips so that the portion with
the head is about . 5 cm long.
Push the nails through the
holes in the two strips (A,B)
and hammer down the cut ends to
rivet the two strips together.
It is best to begin by riveting
the strip at its center and
moving out toward each end at
the same time. The strips should
be firmly held together all
-60-
(2) Handle
Zi
>'-5V
=r
Notch
along their length.
Make a narrow notch in one end
of the wood (D) the width of
a saw blade. This notch ought
to be about 1 . 5 cm deep. Insert
the end of the bi-metal strip
into this notch to complete the
device.
c. Notes
(i) This device is used to demonstrate the fact that metals expand when they
are heated. When the bi-metal strip is held in a flame, it will bend in the
direction of the steel since the aluminum expands more than does the steel.
(ii) Different combinations of metals (e.g., copper and steel, brass and alu-
minum, etc.) can be used with the same results.
(iii) The metal strips may be soldered together as opposed to riveted. Melt a
thin layer of solder onto the surface of one of the two strips. Lay the other
strip on top of it and hold the soldering iron down on both strips until the
solder melts between the two strips. Keep the two strips pressed together with a
screwdriver or other object to prevent them from coming apart before the solder
cools. Repeat this process until the two strips are soldered all along their
lengths. (Note: This procedure will not work if aluminum is used as one of the
metals unless special solder is used.)
-61-
B. VOLUMETRIC MEASURES
Bl. Burette
LI
(1) Tube
2 —
(2) Clamp
a. Materials Required
Components
(1) Tube
Qu I tems Required
1 Glass Tube (A)
1 Glass Tube (B)
1 Glass Tube (C)
1 Rubber Tubing (D)
Dimensions
45 cm long, 1.3 cm
outside diameter,
1 . 1 cm inside diameter
4 cm long, . 7 cm
outside diameter,
0.5 cm inside
diameter
9 cm long, . 7 cm
outside diameter,
0.5 cm inside
diameter
10 cm long, 1.0 cm
outside diameter
(2) Clamp
Pinch Clamp (E)
IV/A4
-62-
b. Construction
(1) Tube
p^u
/*-
Rubber
Tube (D) •<
I I
-Glass Tube (A)
>• Glass Tube (B)
■S
u
>
Glass Tube (C)
Insert the glass tubing (B) into
the end of the rubber tubing (D)
so that the ends of both pieces
of tubing are even. Insert
this end into one end of the
large glass tubing (A) for a
distance of about 1-1.5 cm.
If the seal between the rubber
and large glass tubing is not
watertight, use thin rubber
sheeting (e.g., balloon mater-
ial) to fill in the gas. Seal
this joint with glue to insure
a watertight fit. Draw out one
end of the remaining piece of
glass tubing (C) in a flame to
form a narrow neck. Break off
the neck, and fire polish the
end of the tube. Insert the
wide end of this tube into the
end of the rubber tubing (D)
for a distance of about 2 cm.
Check the tube now for water-
tightness .
Detail
(2) Clamp
Use the clamp (E) to regulate
flow in the burette. Be sure
the clamp is large and strong
enough to completely shut off
flow from the burette.
c. Notes
(i) The most common use of the burette in chemistry is in doing titrations.
-63-
Quite often they are used in pairs, and must always be supported by a stand.
(ii) Each burette needs to be fitted with a scale. Attach a long, thin strip
of paper to the burette tube with transparent tape. Fill the burette from a known
source (e.g., a plastic syringe) one milliliter at a time and mark the level of
the meniscus on the paper. Place the "0" mark in such a way that several milli-
liters of liguid will still remain in the burette when "0" is reached as this will
insure greater accuracy.
(iii) A glass bead just slightly larger than the internal diameter of the rubber
tubing may be used in place of
Glass Tube
Glass Bead
Rubber Tube
Glass Tube
the pinch clamp. Push the bead
into the rubber tubing before
inserting the glass nozzle.
The bead will seal the rubber
tube. To dispense liquid from
the burette, squeeze the tube
between thumb and forefinger
at the location of the head.
\J
Cross Section
(iv) Because of the use of rubber tubing in this burette, it is not suitable for
use with strong corrosives that attack rubber.
-64-
BZ. Measuring Glass
/ \
— 3oo
(1) Bottle
a. Materials Required
Components
(1) Bottle
b. Construction
(1) Bottle
q u Items Required
1 Glass Bottle (A)
Dimensions
Variable
Use a glass bottle (A) with
straight sides and a flat
bottom. Make graduations by
calibrating the bottle using a
known source. The graduations
may be tape, paint, or scratches
on the glass itself.
c. Notes
(i) Inaccuracies may occur due to transfer of liquid from the known source,
failure to wait for liquid to "settle" before making calibration marks, and human
error in marking exact height of liquid. However, for most purposes these
measuring glasses are adequate.
(ii) Graduations may be made every 10, 25, 50, or 100 ml, depending on the size
of the bottle and the uses to which it is to be put.
-65-
c. Notes
(iii) If the bottle is narrow enough in diameter, the graduations may be made
closer together (i.e., every milliliter), but the accuracy will not approach that
of a commercially made graduated cylinder.
-66-
B3 . Dropper
fee
Z>
(1) Dropper
a. Materials Required
Components
(1) Dropper
b. Construction
(1) Dropper
Qu I tems Required
1 Dropper
Dimensions
BI0L/II/A6
Construct the dropper as
described in BI0L/II/A6.
c. Notes
(i) Since commercial droppers are usually readily available and inexpensive,
this item is as easily purchased as it is improvised.
-67-
B4. Pipette
(1) Pipette
a. Materials Required
Components
(1) Pipette
b. Construction
(1) Pipette
Q u I tems Required
1 Transfer Pipette
Dimensions
BIOL/VII/A5
Construct the pipette as
described in BI0L/VII/A5.
c. Notes
(i) The pipette is used to transfer and precisely measure quantities of
liquids .
B5. Volumetric Flasks
a. Materials Required
Components
(1) Bottle
b. Construction
(1) Bottle
(2) Cap
c. Notes
Qu I tems Required
1 Transparent Glass
Bottle (A)
1 Bottle Cap (B)
Dimensions
Variable
To fit bottle (A)
Select any common qlass bottle
(A) with a narrow neck.
Use a cap seal (B) which will
be airtight to prevent leakage
and evaporation.
(i) The flasks must be calibrated from a known source. Put a singl e calibration
mark on the neck of the bottle to indicate its capacity. This may be done with
paint, tape, a scratch mark, etc.
-69-
B6. Specific Gravity Bottle
(1) Bottle
a. Materials Required
Components
(1) Bottle
b. Construction
(1) Bottle
q u I terns Required
1 Pill Bottle (A)
1 Rubber or Cork Stopper (B)
1 Glass Tube (C)
Dimensions
5 cm hiqh, 3 cm
diameter
To fit bottle (A)
8 cm lonq, . 5 cm
outside diameter,
. 3 cm inside
diameter
Simply insure that there are
airtiqht seals between the
stopper (B) and bottle (A) , and
between the qlass tube (C) and
cork (B) .
C. Notes
(i) To use the specific qravity bottle, first remove the stopper and tubing and
fill the bottle to the brim with the liquid to be measured. Reinsert the stopper,
making sure liquid flows completely out of the end of the tubing and that there
is no air trapped in the bottle. Wipe away the excess liquid on the outside of
the bottle. Accurately weigh this amount of liquid and subtract the mass of the
empty specific gravity bottle. Compare the mass of the liquid to that of an equal
-70-
volume of water (found in the same way) to find the specific gravity of the liquid.
(ii) A screw-top bottle may be used instead of the stopper arrangement. Punch
a hole in the top and seal the joint between the tubing and top with waterproof
cement .
-71-
IV. SUPPORTS, STANDS, AND HOLDERS
A. HOLDERS
Holders are classified as small, portable, hand-held devices used to support other
pieces of apparatus.
B. SUPPORTS AND STANDS
These devices are used to hold items stationery for relatively long periods of time.
Al . Tweezers (Forceps)
-72-
A. HOLDERS
(1) Tweezers
a. Materials Required
Components
(1) Tweezers
b. Construction
(1) Tweezers
Qu I tems Required
1 Forceps
Dimensions
BI0L/II/A4
See BI0L/II/A4 for construction
details .
c . Notes
(i) Uses of forceps in chemistry operations include the handling of small
items or radioactive materials.
-73-
A2 . Multi-Purpose Design Holder
(1) Clamp
(2) Handles
(4) Guide
(3) Spring
a. Materials Reguired
Components
(1) Clamp
(2) Handles
(3) Spring
(4) Guide
b. Construction
(1) Clamp
Qu I tems Required
2 Metal Strapping (A)
1 Wood Block (B)
4 Nails (C)
1 Heavy Iron Wire
(coat hanger) (D)
2 Metal Strapping (E)
4 Nails (F)
Dimensions .
B cm x 1.5 cm
2cmx 4 cm x 15 cm
0.5 cm thick x 1 cm
long
Approximately 30 cm
long
1.5 cm x 3.5 cm
0.5 cm thick x 1 cm
long
Bend the two pieces of metal
strapping (A) as indicated.
0.5
Cut Along
This Line
With a pencil and ruler, section
the wood block (B) as shown.
Cut two wedges and discard the
triangular portions as waste.
-74-
Nails (C)
Fasten one strapping clamp to
the short end of each of the
handles with the nails (C) .
Clamp a pencil or stick of
about 0.8 cm diameter in a
vise, Starting at the center
of the wire (D),coil the wire
around the pencil. Make at
least six turns, or a coil
that extends beyond the width
of the wood block (2 cm) by
one wire-thickness on each
side, Leave at least 9 cm of
straight wire at each end of
the spring.
Approximately 4 cm from the
spring, make a 90' bend in
each straight section of wire,
as shown. One cm from each
of the first bends, make a
second 90' bend.
Slide the spring on to one of
the handles as shown.
Slide the second handle into
place.
■/;>-
Bend
N a i 1(F
Nail
Top View
Trim excess wire to within 1.5 cm
of the edge of the handle. Bend
this remaining wire around
handles to hold the spring in
place.
Lay the holder on its side.
Slide one small piece of
strapping under the spring as
shown. Secure the strapping
in place on one handle with
one nail. Nail a second
guiding nail into the other
handle just at the edge of
the strapping. Turn the
holder over and repeat with
another small piece of
strapping. These guides
keep the handles from twisting
out of alignment.
c. Notes
(i) This design is based on the spring-type clothespin. If one isavailable,
it will be a helpful construction guide.
(ii) Squeezing the handles together will cause the clamp to open and close.
(iii) The sizes of the components used in this item will vary with the use to be
made of the holder. The clamp and handle can be reduced in size for use with
test tubes, or enlarged for use with large flasks.
(iv) For a simpler version of this design, three or four strong rubber bands
provide the spring action. Cut the handles and attach the clamps as described.
Then place the two handles together as indicated in the diagram. Wrap the rubber
bands around the top part of the handles to draw them together. The chief
problem with using rubber bands is that they will deteriorate and must be replaced
from time to time.
Rubber Bands
A3. Test Tube Holder
-76-
(1) CI
(2) Handle
amp
a. Material Required
Components
(1) Clamp
(2) Handle
b. Construction
( 1 ) Clamp
Qu
2
Items Required
Metal Strapping
Thin Wire (B)
Wood Block (C)
Wire (B)
(2) Handle
Slit
ons of
Nails (D)
Dimensions
20 cm long
Approximately . 1 cm
thick, 4-5 cm long
Approximately
10 cm x 3 cm x 2 cm
Bend two loops in each piece
of strapping (A) as shown. Fit
the smaller loops to the test
tubes to be used. Wrap a small
piece of wire (B) around the
two pieces of strapping at the
point where they curve inward,
just behind the front loops, to
hold the pieces together.
Cut a slit about halfway down
the center of the block (C) .
Insert the flat portions of the
strapping clamps into the slit.
Secure the clamp to the handle
with two nails .
c, Notes
(i) To open this clamp, squeeze together the large loop between the handle and
the wire. Release the loop to close the clamp.
(ii) This design is best suited for small, light-weight test tubes.
(iii) A quick and convenient holder for handling hot test tubes can be made with
a piece of paper measuring approximately 15 cm x 8 cm. The paper is folded into
-77-
thirds, lengthwise, to form
a strip. This strip can be
wrapped around a test tube
near the top. then grasped
tightly, next to the test tube.
A4 . Wooden Pinch Clamp
(2) Fulcrum
(3) Band
1) Handles
a. Materials Required
Components
(1) Handles
(2) Fulcrum
(3) Band
b. Construction
(1) Handles
(2) Fulcrum
Qu Items Required
2 Wooden Strips (A)
1 Metal Staple or Tack (B)
2 Rubber Bands (C)
Staple (B)
Dimensions
2 cm x 8 cm x 0.5 cm
1 cm wide
0.5 cm x 9 cm
Sand any splinters or rough
edges from the wood strips (A)
Drive the staple (B) or tack
into the middle of one of the
handles. Allow about 0.5 cm
of the staple or tack to
protrude from the wood.
(3) Band
Place the handles together
with the fulcrum between them.
Wrap the two rubber bands (C)
tightly around the handles at
a point just in front of the
fulcrum.
C. Notes
(i) If the rubber bands are sufficiently tight, it should be possible to
-79-
completely close off the flow
of a liquid such as water through
1 cm wide rubber tubing,
(ii) To completely close off plastic tubing and heavier rubber tubing, it will
be necessary to bend the
tubing back upon itself and
secure the clamp at the bend.
(iii) If pinch-typeclothespinsare available, they may be substituted for this
clamp. However, it will be necessary to bend rubber tubing as well as plastic
tubing back upon itself, as in the above illustration, in order to completely
close the tubing with a clothespin clamp.
-80-
A5 . Wooden Screw Clamp
(2) Bolt Assemb ly
(1) Jaws
a. Materials Required
Components
(1) Jaws
(2) Bolt Assembly
b. Construction
(1) Jaws
(2) Bolt Assembly
Qu Items Required
2 Wood (A)
1 Bolt (B)
1 Wing Nut (C)
Dimensions
3.5 cm x 3.5 cm x
0.7 cm
. 5 cm diameter,
approximately 4-5 cm
long
To fit bolt (B)
Sand the wood squares (A)
to remove rough edges and
splinters. Drill a hole
0.6 cm in diameter in the
center of each square.
Insert the bolt (B) through
the hole in each square and
check to see that the holes
are just large enough to
permit the bolt to slide
through easily . Screw the
wing nut (C) in place on
the bolt.
c .Notes
(i) To use this clamp with rubber tubing, a short (approximately 4 cm long)
section of tubing of the same type as that in use is cut. The tubing in use is
passed through the jaws on one
side, as close to the bolt as
possible. The short section
of tubing is passed through
the jaws on the opposite side
to balance the force of the
clamp. By turning the wing nut
to tighten the clamp, the flow
of a liguid or gas through
rubber tubing can be controlled
or shut off completely.
(ii) The flow rate of a liguid or gas through plastic tubing can be controlled
in the same way, but the stiffness of p lastic tubing makes it difficult to close
the tubing completely. To close
plastic tubing, it is necessary
to bend the tubing back on
itself, passing each section
of the tubing through the clamp
and tightening the wing nut
as much as possible.
B. SUPPORTS AND STANDS
Bl. Wire Gauze
LH L
jjjnL
1 U u
(1) Wire
Gauze
a. Materials Required
Components
(l)Wire Gauze
b, Construction
(1) Wire Gauze
c. Notes
Qu
1
Items Required
Wire Mesh (A)
Dimensions
Approximately 10 cm x
10 cm of heavy guage
wire
Cut the wire mesh (A) to a
size approximately 10 cm x 10 cm.
Trim off sharp ends.
(i) This item is generally used in conjunction with the tripods and ring stand
described in the sections that follow. The wire screen is placed on the tripod,
heating stand, or ring to support a flask or beaker. A burner may be placed
beneath the stand to heat the contents of the container.
B2. Heating Shelf
-«^-~ r^OOOO
^*^ °o oooooo^o
/^^oo o0 o oo ooo o
' o^o°ooo o o o o->°Jo ^>
<g?oW°nOOp0 C
oo
O O 0g oO oO" oOj Ogo y
ooo" og o0^ o5> o /
O ?^goo0 p0 o /
(1) Shelf
a. Materials Required
Components
(1) Shelf
Qu
:
Items Required
Tin Can Top or Bottom (A)
Dimensions
10 cm diameter or
larqer
b. Construction
(1) Shelf
Remove the top (A) or bottom
from a tin can. Punch many
holes in it with a larqe
nail.
c. Notes
(i) This item is used in the same way as the wire qauze (IV/B1); that is, to
support a flask, beaker, or other container upon a tripod or similar support.
(ii) This is also a useful item to keep hot glass from contactinq the tabletop.
-84-
B3. (1) Tripod (Tin Can)
(1) Tin Can
Tripod
a. Material Required
Components
Qu Items Required
(1) Tin Can Tripod 1 Tin Can (A)
b. Construction
(1) Tin Can Tripod
Dimensions
Approximately 8 cm
diameter, 12 cm high
Cut a circle about 5 cm
diameter from the bottom of the
can (A) . Mark the position for
three legs, evenly spaced
around the can. Allow a ring
of about 1.5 cm at the top of
the tripod before marking the
legs. Allow approximately
2.5 cm for the width of each
leg. Then cut along the marked
lines to produce the three legs.
With pliers, bend in the outside
edge of each leg slightly to
provide extra support .
C.Notes
(i) This tripod is simple to make, but it must be used with caution because of
sharp edges and instability. It is suitable for supporting lightweight items,
such as a funnel.
B3 (2) . Tripod (Strappings)
-86-
Top
(2) Legs
a. Materials Required
Components
(1) Top
(2) Legs
b. Construction
(1) Top
(2) Legs
q u Items Required
i Metal Strapping (A)
3 Metal Strapping (B)
Dimensions
1.5 cm x 42 cm
1.5 cm x 34 cm
Bend the section of strapping (A)
into a circle and secure the
ends with a metal rivet.
Fold each of the three sections
of strapping (B) in half and
pinch the fold closed. Secure
the open ends of each leg to
the top with metal rivets.
c. Notes
(i) The dimensions given produce a tripod that is useful for most applications,
but this tripod can also be made larger or smaller by varying the length of the
strapping used.
B3 (3) . Tripod (Wire)
1) Wire Tripod
a. Materials Required
Components
(1) Wire Tripod
b. Construction
(1) Wire Tripod
C .Notes
Qu I tems Required
3 Heavy Wire
Dimensions
. 2 cm diameter,
40 cm long
Twist together the ends of two
pieces of wire (A) for
approximately 15 cm to form
one leg. Twist the free ends
of these two pieces together
with each end of the third
piece of wire. Make each
twisted leg 15 cm long. Bend
the legs down to form a tripod
with a level top, as illustrated.
(1) This size tripod is useful for most applications, but it may also be made
larger or smaller by varying the length of the wire used.
B4 . Collapsible Heating Stand
(2) Frame
(1) Legs
a. Materials Required
Components
(1) Legs
(2) Frame
Qu I tems Required
2 Thick Wire (A)
2 Metal Sheeting (B)
2 Metal Strapping (C)
Dimensions
0.4 cm diameter,
45 cm long
10 cm x 3 cm
1.5 cm x 1 6 cm
b. Construction
(1) Legs
Bend the two pieces of heavy
wire (A) to the shape indicated.
(2) Fi
Roll each of the rectangular
pieces of metal sheeting (B)
into long tubes that just fit
around the legs .
€
c. Notes
D
Strapping
Roll 3 cm at each end of the
metal strapping pieces (C)
around each end of the tubes.
Insert the free ends of the
legs (A) into the ends of
the tubing (B) to complete
this stand.
(i) Like the tripods, this stand is generally used with wire gauze (IV/B1)
or heating shelf (IV/B2) .
(ii) When this stand is not in use, the legs may be removed for ease in storing.
-90-
B5 . Ring and Burette Stand with Attachments*
-* -(1) Ring and Burette
Stand
* Adapted from C. S. Rao (Editor), Science Teachers' Handbook, (Hyderabad, India:
American Peace Corps, 1968), pp 144-' TW.
-91-
(2) Burette Clamp
(4) Ring
(5) Support Block
a. Materials Required
Components
Qu
Items
Required
Ring and
(i) Burette Stand
1
Wood
Block (A)
4
Wood
Block (B)
1
Wood
Block (C)
Dimensions
14 cm x 18 cm x 2 cm
2 cm x 4 cm x 1 . 5 cm
3 cm x 2 cm x 40 cm
-92-
(2) Burette Clamp
(3) Large Clamp
1 Metal Strapping (D)
2 Metal Strapping (E)
- Heavy Wire (F)
1 Metal Strapping (G)
2 Metal Strapping (H)
1 Heavy Wire ( I )
(4) Ring
(5) Support Block
b. Construction
1
Metal Strapping (J)
2
Metal Strapping (K)
1
Heavy Wire (L)
:
Wood Block (M)
Nails (N)
(1) Ring and Burette Stand
Foot
Base (A)
1 . 5 cm x 27 cm
1.5 cm x 5 cm
0.2 cm diameter,
10-12 cm long
1.5 cm x 35 cm
1.5 cm x 5 cm
. 2 cm diameter,
10-12 cm long
1.5 cm x 50-60 cm
1.5 cm x 5 cm
0.2 cm diameter,
10 cm long
5cmx2cmx4cm
0.35 cm diameter,
8 cm long
Sand all the wood blocks to
remove splinters and rough
edges. Nail a small wood
block (B) to each corner of
the flat block (A) to make
feet .
In the center of one of the
short sides of the base (A)
cut a rectangular notch 3 cm
long x 2 cm wide.
Drill 0.6 - 0.7 cm holes at
1 cm intervals all the way
through the long block (C)
as shown.
-93-
R\
(2) Burette Clamp
Stand Attachment
Tightening
Clip (E)
Tightening
Clip (E)
Adjustment Pin (F)
\-
1.0
Fit this block into the
rectangular notch in the base
(A) and nail it in place to
form the upright.
Bend the piece of metal
strapping (D) as shown. Adjust
the stand attachment section
so that it will fit securely
around the upright of the stand,
yet be able to slide up or
down along the upright.
Bend two small pieces of
strapping (E) as indicated
to form tightening clips.
Fit them around the straight
section of the burette clamp
to hold the clamp tightly
closed.
Bend a 10 - 12 cm piece of heavy
wire (F) as indicated to make an
adjustment pin. Adjust the
width between the legs to match
the holes drilled in the
upright .
-94-
Stand
Attachment
Tightening
Clip (E)
Drill a hole approximately
0.4 cm diameter in the burette
clamp as shown .
Burette
Clamp
(3) Large Clamp
Adjustment
Pin (F)
To position the burette clamp
on the stand, slide the
rectangular section of the
clamp along the upright to
the desired height, with the
clamp facing the base of the
stand. Align the hole in the
burette clamp with a hole in
the upright. Insert one of
the legs of the adjustment
pin through the burette clamp
and into the upright. Insert
the other leg of the pin into
the next higher hole of the
upright .
Bend the piece of strapping (G)
in the same general shape as
the burette clamp, but slightly
larger.
Construct two tightening clips
(H) just as with the burette
clamp. Position the clips on
the clamp to hold it closed.
-95-
T"
1.0
K
(4) Ring
Tightening
Clips (K)
Construct an adjustment pin
from a piece of heavy wire (I) .
Follow the procedure given for
the burette clamp,
Drill a hole in the large clamp
for the adjustment pin, as
described for the burette clamp.
Bend the piece of metal
strapping (J) into the shape
shown. Bend the ends of the
strapping into loops approx-
imately 0.4 cm diameter.
Make two tightening clips
according to the directions
given with the burette clamp
from the strapping (K) .
Secure them in the positions
shown.
Construct a pin to hold the
end loops together by bending
the length of heavy wire (L)
in half.
To position the ring on the
stand, slide the rectangular
section of the ring along with
the upright to the desired
height, with the clamp facing
the base of the stand. Push
the pin through the end loops.
(5) Support Block
4
Lb
s
"I
1.0
Drive two nails (N) all the
way into a small block of
wood (M) 1 cm apart.
Stand
Position the support block to
prevent the front of the ring
from leaning forward under the
weight of materials placed on
it. Insert the two prongs of
the support block into the two
holes in the upright just
below the ring.
Support
Block
C.Notes
(i) To loosen the burette clamp or large clamp, slide the tightening clips
toward each other. To tighten, slide the clips away from each other.
(ii) Although the burette clamp and large clamp have adjustment pins to hold
them in place, they are much more stable when the support block is pushed into
theupright iammediately beneath the clamp. This prevents the burette clamp or
large clamp from leaning forward.
(iii) The ring will safely support masses up to about 1 kilogram. It can
support round-bottomed containers or flat-bottomed containers with a diameter
slightly larger than that of the ring. To support smaller containers, a wire
gauze (IV/B1) or heating shelf (IV/B2) may be placed on the ring. For large
conatiners, a more stable support, such as one of the tripods (IV/B3) or the
collapsible heating stand (IV/B4) is recommended.
B6. Multipurpose Stand
-97-
(2) Flask Support
(3) Test Tube
Support
(4) Heating
Clamp
(1) Base
a. Materials Required
Components
(1) Base
(2) Flask Support
0<i
Items Required
1
Wood (A)
1
Heavy Wire
(coat hanger) (B)
(3) Test Tube Support 4
(4) Heating Clamp
b. Construction
(1) Base
Heavy Wire
(coat hanger) (C)
Heavy Wire
(coat hanger) (D)
Heavy Wire
(coat hanger) (E)
Dimensions
9 cm x 4 cm x 18 cm
0.2 cm diameter,
35 cm long
0.2 cm diameter,
40 cm long
0.2 cm diameter,
15-20 cm long
0.2 cm diameter,
20 cm long
Drill seven holes approximately
0.2 cm in diameter into the
wood block (A) as shown. If
a larger block is used, or if
more attachments are desired,
drill more holes,
(2) Flask Support
Bend the piece of heavy wire (C)
as shown to form the base of
the flask support. Make the
circular loop about 6 cm in
diameter.
Bend the shorter piece of heavy
wire (B) into a loop to form
a support for the neck of a
flask or light-bulb flask (IV/A1),
Make the open loop about 4 cm
in diameter.
Insert the two sections of the
support into adjacent holes in
the base. Adjust them so that
they will support a flask or
light-bulb flask as illustrated.
-99-
(3) Test Tube Support
Rod or
Test Tube
Bend Here
8-10
Use pliers to bend each of the
pieces of heavy wire (D) around
a wooden rod or test tube of
the desired diameter (2 cm for
example) . Follow the steps
illustrated.
Insert the supports into holes
in the base.
(4) Heating Clamp
10 - 15
c. Notes
Bend the piece of heavy wire (E)
into loop just as for the test
tube support shown above.
However, tilt the loop at an
angle, rather than vertically
as was done for the test tube
supports. Insert the heating
clamp into one of the holes in
the base.
(i) Sizes and number of the supports constructed, as well as the size of the
base, may be varied to suit individual needs.
(ii) The heating clamp is used to hold a test tube at an angle while its contents
are heated. Supporting the test tube at an angle presents a greater area to be
heated. As a safety measure,
it allows the mouth of the
test tube to be pointed away
from everyone in the vicinity.
-100-
B7 . Rack for Light-Bulb Glassware
(2) Spring
Clamp
a. Materials Required
Components
(1) Base
(2) Spring Clamp
b. Construction
;i) Base
q u Items Required
1 Wood (A)
1 Wood (B)
1 Wood (C)
3
Metal Strapping (D)
Top (C)
Upright (B)
(1) Base
Dimensions
8 cm x 24 cm x 2 cm
9 cm x 24 cm x 2 cm
4 cm x 24 cm x 2 cm
1 cm x 14 cm
Drill or cut three circular
holes, 6 cm in diameter in
the large piece of wood (A) .
Allow about 1.5cm between
holes .
Attach top (C) and upright
(B) with glue and screws as
shown,
Base (A)
-101-
Drill a hole approximately 0.5 cm
diameter in the center of each
of the pieces of metal strapping
(D) . Bend each piece of metal
strapping into the shape shown.
Center each clamp over each hole
in the base. Secure each clamp
to the top (horizontally) piece
of the base with a screw.
Notes
(i) The spring clamp holds the neck of a light-bulb flask securely, while the
hole in the base supports the round bottom of the flask.
(ii) This design may be modified to accommodate more flasks, or flasks of
different sizes.
-102-
Stand for Light-Bulb Glassware
a. Materials Required
Components
(1) Flask Stand
b. Construction
(1) Flask Stand
Qu Items Required
1 Wood Block (A)
c. Notes
1) Flask
Stand
Dimensions
9 cm x 9 cm x 4 cm
Drill or cut a circular hole
through the center of the block
(A) . Adjust the diameter of
the hole to the size of the
light-bulb flask used:
6 cm diameter hole for
bulbs from 60 to 200
watts. 7 cm diameter
hole for larger bulbs.
(i) Another stand for a single piece of light-bulb, or any round-bottomed
glassware, can be made with a piece of heavy rope approximately 3 cm in diameter.
The rope is cut to a length
slightly shorter than the
maximum circumference of the
flask, and the ends of the
rope are taped or spliced
together to form a ring.
-103-
Bamboo Test Tube Rack
(1) Base
|Q (2) Test Tube
Holder
a. Materials Required
Components
(1) Base
(2) Test Tube Holder
b. Construction
(1) Base
(2) Test Tube Holder
Qu
1
Cut
Items Required
Wood Block (A)
Bamboo Sections (B)
Dimensions
1 cmx 7 c m x 1 8 cm
Approximately 2.5 cm
outside diameter,
10 cm long
Sand the wood block (A) to
remove splinters and rough
edges.
Select bamboo sections (B)
with thick walls (at least
0.2 cm). Cut away approximately
half the length of each bamboo
section, but leave one upright
piece as shown. Cement these
cylinders to the base.
-104-
C.Notes
(i) The upright section remaining on each bamboo cylinder is used to support
test tubes upside down for drying.
(ii) The size of the base may be varied to accommodate a convenient number of
bamboo cylinders . The diameter of the bamboo cylinders may be varied to suit the
size of the test tubes used.
-105-
B10. Wooden Test Tube Rack
o o o o o o
o o o o o o
(1) Test Tube
Rack
/
s
a. Materials Required
Components
Qu
Items Required
(1) Test Tube Rack
2
Wood (A)
2
Wood (B)
b. Construction
(1) Test Tube Rack
Dimensions
8 cm x 20 cm x 1 cm
8 cm x 12 cm x 2 cm
Drill 12 holes, 2.2 cm in
diameter at evenly spaced
intervals in one of the
larger pieces of wood (A)
to form the top of the rack.
Secure the sides (B) to the
top (A) as shown, with nails
or cement. Secure the
bottom (A) in place with
nails or cement.
c. Notes
(i) For larger or smaller test tubes, the dimensions may be varied.
-106-
V. GLASSWARE AMD CROCKERY
A. GLASSWARE
This section describes the construction of various items of laboratory glassware.
The chief activity in making these is glass cutting, which is described in detail in
a separate section. Refer to GLASSWARE TECHNIQUES AND ACCESSORIES (I) for specific
direction for cutting and working glass.
B. CROCKERY
Included in this section is one item composed of concrete.
-107-
A. GLASSWARE
AT. Light Bulb Glassware
(1) Flask
or
Test Tube
a. Materials Required
Components
(1) Flask or Test
Tube
b. Construction
(1) Flask or Test
Tube
Sawing
Qu Item Required
1 Clear Incandescent
Light Bulb (A)
Dimensions
Varies
Secure a hacksaw blade in a
vise. Hold the bulb (A)
horizontally, and wrapped in
clcth for safety. Cut around
the edge of the base near the
terminals. Remove the end
thus cut.
"Adapted from C. S. Rao (Editor), Science Teachers' Handbook , (Hyderabad, India: The
American Peace Corps, 1968), pp 146^T?7^
-108-
Heat cutting
Cut Here
Tape
With a triangular file,
puncture the inner seal and
remove all the parts from
inside the bulb. Smooth cut
edge with emery paper or the
file.
Wrap a piece of tape around
the neck of a clear bulb (A),
about 0.3 cm from the base, as
a cutting guide. With a
triangular file or glass cutter,
make a continuous scratch all
the way around the neck of the
bulb.
Remove the tape, and use the
electric bottle cutter (I/F2)
to heat the scratch until the
bulb cracks all the way around.
Discard the base and internal
components.
Wrap the lower portion of the
bulb in cloth to protect the
hands. Hold the cut edge in
a gas or alcohol burner flame
until the edge softens and
curls back upon itself to
form a smooth lip.
c. Notes
(i) The average 150 watt bulb forms a flask of about 150 ml capacity, the
average 200 watt bulb a flask of about 200 ml capacity
(ii) Bulbs of 100 watts or less may be used for test tubes.
(iii) Small test tubes may also be made from glass medicine vials or discarded
antibiotic ampules,
(iv) The bulb is made of thin enough glass to be heated safely while containing
a liquid.
(v) The glassware made from light bulbs requires special supports to hold it
upright. Consult the section on Supports, Stands, and Holders (IV) for suggestions.
-109-
A2. Beaker
(1) Beaker
a. Materials Required
Component^
(1) Beaker
b. Construction
(1) Beaker
Qu Items Required
1 Wide-bottom Jars or
Bottles (A)
Dimensions
Varies
Cut off the bottom portion of
jars or bottles (A) to make
beakers of various sizes (I/F2),
Smooth the rough edge by
filing with emery paper or a
file.
c. Notes
(i) Since bottles and jars are generally made of soft glass, rather than hard,
heat resistant glass; beakers made from bottles or jars cannot be used for hot
substances or for substances that are to be heated. When heated, they will break.
-110-
A3. Funnel
(1) Funnel
a. Materials Required
Components
(1) Funnel
fiu
1
Items Required
Glass Bottle (A)
Dimensions
Varies
b. Construction
(1) Funnel
Cut off the top portion of
narrow-mouthed glass bottles (A)
to make funnels of various
sizes (I/F2).
-in-
A4. Bell Jar
\
(1) Jug
a. Materials Required
Components
Qu
Items Required
Dimensions
(1) Jug
1
Glass Jug or Carboy (A)
4-8 liters
1
Rubber or Cork Stopper (B)
To fit Jug (A)
b. Construction
0) Jug
Cut off the bottom of the glass
jug or carboy (A). Sand the cut
edge smooth with emery paper.
Seal the neck of the jug with
the stopper (B).
-112-
A5. Watch Glass
(1) Watch Glass
a. Materials Required
Components
(1) Watch Glass
b. Construction
(1) Watch Glass
Qu Items Required
1 Light Bulb (A)
Dimensions
Varies
Carefully cut the tops off old
light bulbs (A) to make watch
glasses of various sizes.
Smooth the cut edges by fire
polishing.
c. Notes
(i) The watch glass is commonly used to hold small quantities of a solution fror
which crystals are to be collected.
-113-
A6. Petri Dish
(1) Petri Dish
a. Materials Required
Components
(1) Petri Dish
b. Construction
(1) Petri Dish
Qu Items Required Dimensions
1 Wide-bottom Bottles or Varies
Jars (A)
Cut off the bottom of a wide-
bottom glass. bottle or jar (A).
Make as many as needed. Smooth
the rouqh edge with emery paper.
c. Notes
(i) Jar lids or aluminum foil make satisfactory tops for these dishes. Waxed
paper or cardboard dipped in wax also make suitable covers.
(ii) Petri dishes are often used to hold small quantities of a liquid from which
crystals are to be collected.
(iii) They may also be used to contain food or culture media for growing bacteria,
fungi, or molds. When petri dishes are used for culturing purposes, they must be
used with lids and must be sterilized (BI0L/VII/A2).
A7. Wash Bottle
-114-
(3) Mouthpiece
(2) Delivery Tube
(1) Container
a.
Materials Required
Components
Qu
Items Required
Dimensions
(1) Container
1
Glass or Plastic Bottle
(A)
Approximately 250 ml
capacity
1
2-Hole Stopper (B)
To fit container (A)
(2) Delivery Tube
1
Glass Tubing
Approximately 0.5 cm
diameter, and at least
20 cm longer than
height of container.
(3) Mouthpiece
1
Glass Tubing (D)
About 0.5 cm diameter,
and shorter than
delivery tube.
b.
Construction
(1) Container
Select
a glass or plastic bottl
with a narrow neck and a
capacity of about 250 ml or
larger (.A).
Fit the container (A) with a
two-hole stopper (B).
-115-
(2) Delivery Tube
(C)
Make a nozzle (I/D3) at one end
of the long glass tube (C). Fire
polish both the nozzle and the
other end and let the tube cool.
Next, bend the tube, about 8-10
cm from the nozzle end at a sharp
angle as shown. When it is cool,
carefully push the tube into the
stopper (B) so that it extends to
within 0.5 cm of the bottom of
the container. Trim to the
correct length, if necessary,
and fire polish the end.
Fire polish both ends of the
glass tube (D). About 8 - 10 cm
from one end, make a wide-angled
bend. When the tube has cooled,
push it carefully into the
stopper (B). Insert the stopper
into the container (A).
-t (C)
-116-
c. Notes
(i) To use the wash bottle, fill it with (distilled) water. Direct the delivery
tube in the desired direction and blow through the mouthpiece to force water through
the nozzle in a fine stream.
(ii) If a soft plastic squeeze bottle is used, only the delivery tube and a one-
hole stopper are necessary. Squeeze the bottle to force water out the nozzle.
•117-
A8. Aspirator
(3) Outlet
Tube
(2) Intake
Tube
(1) Container
(4) Drain Tube
a. Materials Required
Components
(1) Container
(2) Intake Tube
(3) Outlet Tube
Qu Items Required
Glass Bottle (A)
2-Hole Rubber Stopper (B)
Glass Tubing (C)
Glass Tubing (D)
Plastic or Rubber Tube (E)
Screw Clamp or Pinch
Clamp (F)
Glass Tube (G)
Glass Tube (H)
Plastic or Rubber Tube (I)
Dimensions
4-8 liter capacity
To fit Bottle (A)
0.5 cm diameter,
approximately 15 cm long
0.5 cm x 10 cm
Approximately 1.0 cm
diameter, 35 cm long
(IV/A4 and A5)
0.5 cm diameter, 10 cm
longer than height of
bottle
0.5 cm x 10 cm
Approximately 1.0 cm
diameter, 35 cm long
-118-
(4) Drain Tube
b. Construction
(1) Container
(2) Intake Tube
(3) Outlet Tube
(E) ( C >
1 Screw Clamp or Pinch
Clamp (J)
1 Plastic or Rubber Tube (K)
1 Screw Clamp or Pinch
Clamp (1)
(IV/A4 or A5)
Approximately 1.0 cm
diameter, 20 cm long
(IV/A4 or A5)
Fit the bottle (A) with a two-
hole rubber stopper (B).
Carefully bore a hole approxi-
mately 1.0 cm in diameter, 2 cm
from the bottom of the bottle.
Make a 90° bend about 5 cm from
one end of the longer glass tube
(C). Insert this tube into one
of the holes in the stopper of
the bottle. Fit the other end
of the tube into the plastic or
rubber tubing (E). Insert the
short glass tube (D) into the
open end of the plastic or
rubber tubing (E).
Construct a screw clamp or pinch
clamp (F) (IV/A4 or A5) to close
the tubing (E).
Make a 90" bend about 5 cm from
one end of the longer glass
tube (G). Insert this tube into
one of the holes of the rubber
stopper (B) such that the
straight section of the tube
reaches within 2 cm of the bottom
of the bottle as illustrated.
Attach the plastic or rubber
tubing (I) to the other end of
the glass tube (G). Fit the
shorter glass tube (H) into the
free end of the tubing (I)
and close it with a clamp (J).
-119-
(4) Drain Tube
Insert the plastic or rubber
tubing (K) into the hole in the
side of the container extending
it 1 - 2 cm inside the bottle.
Seal the tubing (K) in the hole
with epoxy resin. Close the
tube with a clamp (L).
c. Notes
(i) This item may be used to collect gas by water displacement. First, the bottle
is filled with water and all three tubes are closed with clamps. The Intake tube is
then attached to the gas gener-
From Gas Generator To Drain
>■ : F=ni , C
Gas In
Water ■
1C
Water Out
±f
ator and the outlet tube is
directed into a drain or waste
receptacle. When both the
intake and outlet tubes are
opened (drain tube remains
closed) gas will enter the
bottle, and displaced water will
be forced out through the outlet
tube.
Closed
(ii) The aspirator may also be used to provide suction to aid in filtration.
Again, the bottle is filled with water, and all three tubes are closed with clamps.
The intake tube is connected to
Substance
xo be
Fi 1 tered
Suction-filter
Flask
To Drain
Water Out
the suction tube of a suction-
filter flask (VI/A4). The drain
tube is directed into a drain or
waste receptacle. The liquid to
be filtered is poured into the
filter funnel (fitted with
filter paper), and the intake and
drain tubes are opened. The
outlet tube remains closed. The
flow of water from the aspirator
bottle creates a negative
pressure that tends to increase
the rate of filtration in the
suction filtration apparatus.
-120-
B. CROCKERY
Bl. Mortar and Pestle
,(1) Mortar
a. Materials Required
Components
(1) Mortar
(2) Pestle
Qu Items Required
0.5 kg Sand (A)
1.5 kg Cement (B)
1 Tin Can (C)
0.5 kg Modeling Clay
(Plasticine) (D)
Wire Mesh (E)
Epoxy Glue (F)
Light Bulb (G)
Light Bulb (H)
Epoxy Glue (I)
Nail (J)
b. Construction
(1) Mortar
Can (C)
Clay (D)
(2) Pestle
Cross Section
Dimensions
Fine grain
Capacity approximately
0.5 kg
10 cm x 10 cm
100 watts
60 watts
Approximately 10 cm
long
Cut the tin can (C) in half.
Pack the modeling clay
(plasticine) (D) into the bottom
half of the can. Then mold the
clay into the external shape of
the mortar. Make the bottom of
the clay mold smooth and flat,
as this will be the bottom of
the mortar.
-121-
Wire Mesh (E)
Concrete (A & B)
Clay (D)
Cross Section
Bulb (G)
Remove Excess
Concrete
Air
Bubbles
Make a mixture of 3:1 cement (B)/
sand (A) . Add water to make a
thick concrete paste. Next,
cover the mold with a 2 - 3 cm
layer of concrete (A and B).
Cut the wire mesh (E) into 2 cm
wide strips and press the strips
on the coating of concrete.
Cover the entire surface of
concrete with the screening
strips (E).
Fill the remaining space with
concrete. Cover the 100 watt
light bulb (G) with oil and
press it halfway into the mold.
Scrape away and discard any
concrete that overflows the mold.
Level off the top of the
concrete.
Take a thin wooden or metal rod
and push it in and out of the
concrete around the bulb (G),
touching the bulb. Break
up, in this way, any air bubbles
between the bulb and the
concrete.
Allow at least 24 hours or more
for the concrete to dry. Then
cut away the can with a can
opener and tin snips and peel
-122-
(2) Pestle
Cut
Bulb
away the clay mold. Break and
remove the bulb, taking care to
remove all pieces of broken
glass. Place the mortar in a
large can or crock and cover it
with water. Allow it to soak
for three weeks in order to cure.
Add water to the container as it
is absorbed by the mortar.
When the mortar has cured, remove
it from the water and allow it to
dry. Then cover the entire
surface with epoxy glue (F) to
seal the concrete, fill air
bubbles, and provide a smooth
grinding surface.
Cut the metal tip off the 60
watt light bulb (H) with a
hacksaw. Remove the insides.
File the cut edges smooth with
a round file.
Bulb (H)
Nail (J)
Concrete (A & B)
Support the bulb upright in a
container of sand or appropriate
stand and fill the entire bulb
with the concrete paste (A and B).
Insert a nail almost all the way
to the bottom of the bulb, to
provide support for the concrete.
Allow the concrete to dry (at
least 24 hours). Break the glass
glass, leaving the metal end
intact. Cure the pestle immersed
in water for three weeks.
Remove, dry, and coat with epoxy
-123-
glue (I), making sure all air
bubbles are filled.
c. Notes
(i) The mortar and pestle are used to grind crystals or lumps of substances into
powder. The substance to be ground is placed in the mortar, and ground with the
pestle to the desired consistency.
(ii) If the epo*y-coated grinding surfaces of the mortar and pestle become worn
away with use, clean them and reapply a layer of epoxy glue to provide a smooth
surface.
-124-
VI. SEPARATORS AND PURIFIERS
This section on separators and purifiers has been divided into four subsections:
A. MECHANICAL SEPARATORS
These are devices for separating solid/solid, liquid/solid, or solid/liquid
mixtures. Included are magnets, sieves, filtration apparatus, and separatory funnels.
B. DISTILLATIONAPPARATUS
These devices are used for separating liquid solutions and incllde several types
of distillation apparatus.
C. ELECTRICAL SEPARATOR
This device is used in the electrolytic separation of substances and to demonstrate
Faraday's quantitative laws of electrolysis.
D. CENTRIFUGAL SEPARATORS
Centrifugal separators are used to cause the rapid precipitation of materials in
suspension .
■125
A. MECHANICAL SEPARATORS
Al. Magnets
N
S
(1) Bar Magnet
a. Materials Required
Components
(l)Bar Magnet
b. Construction
(1) Bar Magnet
Qu I tems Required
1 Bar Magnet
Dimensions
PHYS/IX/A1, Notes
Purchase a magnet, or magnetize
a steel bar according to the
instructions described in
PHYS/IX/A1, Notes.
c. Notes
(i) Magnets are used to separate ferromagnetic materials from other materials,
such as dirt or sand.
(ii) Magnets in a variety of shapes, materials, and field strength may be
purchased from commercial sources and may be used in place of the bar magnet above.
A2 . Cone Sieve
-126-
(1!
Cone Sieve
a. Materials Required
Components
(1) Cone Sieve
b. Construction
(1) Cone Sieve
;;;;;
Qu I tems Required
1 Wire Mesh (A)
1 Thin Wire (B)
■Cut
Out
■■■■■■■■iSiiiiiiiiiii
■■■■■■■•■•■■■■■■iii*h.
m
Dimensions
Approximately 7 cm x
7 cm
Approximately 10 cm
Cut a circle from the wire mesh
(A) . Then cut out and remove
a seqment of the circle as
shown.
c. Notes
Roll the wire mesh into the
shape of a cone, overlappinq the
edqes slightly. Thread the
thin wire (B) in and out of the
wire mesh, at the overlapped
edges, to hold them together.
(i) This cone may be made larger or smaller by varying the dimensions of the
wire mesh used.
(ii) Material suitable for replacing the wire mesh may be made by dipping a cloth
having a very coarse weave into melted wax, varnish, or starch.
(iii) Sieves are suitable for grading small particles or washing small amounts of
materials under a stream of water.
A3. Basket Sieve
-127-
(3) Handle
J
a. Materials Required
Components
(1) Basket
(2)Fi
(3) Handle
b. Construction
(1) Basket
Qu I tems Required
1 Wire Mesh (A)
4 Thin Wire (B)
1 Stiff, Heavy Wire (C)
1 Thin Wire (D)
1 Wood (E)
Dimensions
Approximately
30 cm x 4 cm
Approximately 20 cm
Approximately 4 cm
diameter, 80 cm long
Approximately
80 cm long
2 cm x 2 cm x 15 cm
Cut the wire mesh (A) according
to the pattern shown, and dis-
card the shaded portions. Then
fold all the flaps up along the
dashed lines. Overlap the cut
edges slightly, and thread the
thin wires (B) in and out of
the wire mesh at the overlapped
edges to hold them together.
-12E
(2) Frame
Bend the heavy wire (C) as shown,
to fit the dimensions of the
top of the basket. Allow an
extension of 8 - 9 cm to fit
into the handle (E) .
(3) Handle
c .Notes
Fold the top 1 cm of the basket
around the frame to the inside,
and lace the thin wire (D) in
and out of the basket mesh to
secure the frame in place.
Drill a hole approximately 0.8
cm in diameter and approximately
halfway through the length of
the wooden handle (E) .
Insert the straight section of
the frame into this hole in
the handle, and cement it in
place.
(i) This basket sieve may be made larger or smaller by varying the dimensions
of the wire mesh, frame, and handle used.
(ii) This sieve is used just as the funnel sieve in the preceding section, but
for larger amounts of material.
-129-
A4 . Suction-Filter Flask
(1) Flask
(2) Funnel
(3) Suction Tube
To Aspirator
a. Materials Required
Components
(1) Flask
(2) Funnel
(3) Suction Tube
q u Items Required
1 Glass Bottle (A)
1 1-Hole Rubber Stopper (B)
1 Glass Tube (C)
1 Funnel (D)
1 1-Hole Rubber Stopper (E)
1 Filter Paper (F)
1 Rubber Tube (G)
'1 Glass Tube (H)
Dimensions
Capacity 250-500 ml
To fit bottle (A)
. 5 cm diameter,
6 cm lonq
V/A3
To fit neck of funnel
(D)
Approximately 15 cm
diameter
1 . cm diameter,
15 cm lonq
. 7 cm diameter,
10 cm lonq
-130-
b. Construction
(1) Flask
Glass Tube (C)
CD „ . Hole
Bore a hole (I/E2) just slightly
smaller than 1.0 cm in diameter
in the side of the bottle (A)
near the top. Insert the glass
tube (C) into the rubber
stopper (B) so that approximately
half the tube protrudes from
the top of the stopper. Fit
the stopper into the mouth of
the bottle.
(2) Funnel
Stoppers (B,E) With
Glass Tube (C)
Between Them
Insert the protruding end of
the glass tube into the stopper
(E) for the funnel (D) . Push
the two stoppers together, and
fit the funnel stopper into the
neck of the funnel (D) .
(3) Suction Tube
Insert the rubber tubing (G)
into the hole in the side of
the bottle so that about 1 cm
of tubing is inside the bottle.
Seal the tubing in place with
egoxy resin. Insert a short
piece of glass tubing (H) into
the open end of the rubber
tubing.
-131-
c. Notes
(i) A circle of filter paper is folded as illustrated and placed in the funnel.
The suction tube is then connected to the water-filled aspirator (V/A8) . The
material to be filtered is
placed in the filter paper
the funnel. Water is then i i
allowed to drain from the
aspirator. The partial vacuum
thus formed will draw air from
6
)
Fold
' Fold
the flask, and air on the outside will be drawn through the funnel, causing more
rapid filtration to occur.
(ii) Filter paper is available from commercial suppliers, but substitutes include
paper towels, blotting paper, or cotton.
-132-
A5 . Separatory Funnel
(1) Funnel
(2) Delivery Tube
a. Materials Required
Components
(1) Funnel
(2) Delivery Tube
Qu I tems Required
Glass Bottle (A)
Rubber Stopper (B)
1-Hole Rubber Stopper (C)
Glass Tubing (D)
Rubber Tubing (E)
Wooden Pinch Clamp (F)
Dimensions
Capacity 250-500 ml
Approximately 2 cm
diameter (large end)
To fit bottle (A)
. 7 cm diameter,
15 cm long
1 cm diameter,
8 cm long
IV/A4
-133-
b. Construction
(1) Funnel
Select a clear glass bottle (A)
with a tapered, narrow neck.
Drill a hole in the bottom of
the bottle and enlarge it suffi-
ciently to receive the rubber
stopper (B) . Smooth the rough
edge with emery paper before
sealing.
(2) Delivery Tube
QZ><
5 H J" — 5 — >J
ZZD (T )
t
Discard
t
Nozzle
t
Connector
Heat the glass tubing (D) with
a burner and draw it out near
one end and cut as shown to
leave a 5 cm long nozzle and a
5 cm long connector. Carefully
fire polish all cut edges.'
-134-
Glass
Connector
Rubber
Tubing (E)
Fit the glass connector into,
but not through, the one-hole
rubber stopper (C) . Insert the
other end into the rubber
tubing (E) , and connect the
rubber tubing to the nozzle.
Fit the stopper into the neck
of the bottle.
Construct a wooden pinch clamp
(IV/A4) and use it to close the
rubber tubing.
Nozzle
C. Motes
(i) The separatory funnel is used to separate two liquids that do not mix. With
the delivery tube closed, the mixture of liquids is poured into the funnel through
^."0"^ the hole at the top, (bottom of
bottle) . The funnel is then
sealed and shaken vigorously
for several seconds. Then the
funnel is secured in a ring
stand (IV/B4) or other appro-
priate support and allowed to
rest undisturbed until the
liquids separate into layers.
The lower liquid is then drained
through the delivery tube by
opening the pinch clamp. In
order to allow the funnel to drain properly, the stopper must be removed from the
top.
-135-
(ii) A glass bead just slightly larger than the internal diameter of the rubber
tubing may be used in place of
Pinch
Here
G
u
Glass
Tube
Glass
Bead
Rubber
Tube
Glass
Tube
the pinch clamp. Push the bead
into the rubber tubing before
inserting the glass nozzle.
The bead will seal the rubber
tube. To dispense liquid from
the funnel, squeeze the tube
between thumb and forefinger
at the location of the bead.
Cross Section
-136-
B. DISTILLATION APPARATUS
Bl. Simple Distillation Apparatus
a. Materials Required
Components q u
(1) Distilling Flask 1
(2) Delivery Tube
(3) Collecting
Flask
b. Construction
(1) Distilling Flask
(3) Collecting
Flask
Items Reguired
Flask (A)
1-Hole Rubber Stopper
Glass Tubing (C)
Rubber or Plastic
Tubing (D)
Flask or Bottle (E)
Dimensions
Capacity approxi-
mately 200 ml
To fit flask (A)
. 7 cm diameter,
5 cm long
1 cm diameter, approx-
imately 60 cm long
Capacity approxi-
mately 200 ml
Fit the light bulb flask (A) or
other flask with the one-hole
rubber stopper (B) .
-137-
(2) Delivery Tube
Support the flask in a stand,
(IV/B4, B5, or B6) .
Insert a short piece of glass
tubing (C) into the stopper in
the flask. Attach the other
end of the glass tube to a long
piece of rubber or plastic
tubing (D) . Insert another
short piece of glass tubing (C)
into the other end of the
rubber or plastic tubing.
(3) Collecting Flask
c .Notes
Place a flask (E) or jar in a
bowl or pan of cool water and
lead the free end of the
delivery tube into the flask.
(i) A sample of a liguid — impure water, for example — to be distilled is placed
in the distilling flask, and the stopper is inserted into the flask. The liquid
is heated until it boils. As the liquid boils, its vapor travels through the
delivery tube and is cooled enough by air surrounding the tube to condense and
drip into the collecting flask. The water in the bowl helps cool the condensed
liquid still more, as it is quite hot when first collected.
(ii) This simple apparatus is ideal for student participation in simple distil-
lation operations involving small volumes of liquids.
B2 . Condenser
-13E
3) Condensing Tube
(2) Water Jacket
Stand
a.
Materials
Required
Components
Qu
Items Required
(1) Stand
2
1
2
2
Wood (A)
Wood (B)
Nails (C)
Rubber Bands (D)
(2) Water Jacket
(3) Condensing
Tube
1 Plastic or Glass Bottle (E)
1 1-Hole Rubber Stopper (F)
2 Rubber Tubing (G)
2 Glass Tubing (H)
1 Glass Tubing (I)
Dimensions
1 8 c m x 1 5 cmx 1cm
2 5 cmxl5 cmxl cm
3 cm long
5 cm x 9 cm
Capacity approximately
1-2 liters
To fit bottle (E)
1 cm diameter,
3 cm long
0.7 cm diameter
10 cm long
. 7 cm diameter,
10 cm longer than
bottle
-139-
c. Construction
(1) Stand
Nail (C)
Trace around the base of the
bottle (E) on the larger piece
of wood (B) as shown. Cut along
the traced line .
In a similar fashion, make a
small semicircular cutout to
accommodate the neck of the
bottle (E) in one of the
smaller pieces of wood (A) .
Nail the two sections with
cutouts to the third (A) to
form the stand. Drive a nail
(C) into each upright to
anchor the rubber bands (D)
that hold the water jacket in
place.
(2) Water Jacket
Outlet
©
1P^
Take a plastic bottle (E) if
possible, a glass bottle if
necessary. Drill three holes
approximately 1 cm in diameter
in the bottle as illustrated.
nlet
-140-
Glass
Tube (H)
Rubber
Tube (G)
(3) Condensing Tube
Fit each short piece of glass
tubing (H) into a piece of
rubber tubing (G) . Insert each
piece of rubber tubing into one
of the holes in the side of the
bottle. Seal with epoxy resin
if necessary to make sure that
the seal is watertight.
Fit the mouth of the bottle
with a one-hole rubber stopper
(F).
Insert a long glass tube (I)
through the hole in the base of
the bottle, all the way through
the bottle, and through the
rubber stopper to the outside
again.
Rest the bottle in the stand
with the base higher than the
neck and the inlet tube below
the outlet tube. Loop the
rubber bands (D) around the
base and neck of the bottle to
secure it in position.
C .Notes
(i) To use this condenser, fasten a rubber or plastic tube from the flask in
which a liquid is being boiled to the upper end of the condensing tube (that end
protruding from the bottom of the bottle) . Another tube, from a cold water source,
is connected to the inlet (lower) tube, and a third rubber or plastic tube is
attached to the outlet and led to a drain. As hot gas flows through the con-
densing tube, it is cooled by the water jacket and condenses, to drip as a liquid
from the lower end of the condensing tube where it can be collected in a beaker.
-141-
B3. Water Still
(j) Condensing
?ipe
(2) Water Jacket
(Cutaway view)
(1) Frame Support
a. Materials Required
Components
(1) F rame Support
(2) Water Jacket
(3) Condensing
Qu Items Required
4 Wood (A)
1 Wood (B)
2 Metal Strapping (C)
1 Large Tin Can (D)
2 Rubber Tubing (Ej
2 Glass Tubing (F)
er Pipe (G)
1-Hole Rubber Stopper (H)
D imensions
4 cm x 5 cm x 25 cm
2 cm x 16 cm x 25 cm
1 . 5 cm x 2 3 cm
Capacity approximately
1-1.5 kg
! cm diameter,
5 cm long
. 7 C'Fl di amet er
5 cm long
1 will JU Lj i -wi'- ■-. : :-xi.iv. ^^ , j
5 c;;i longer than can
height
Approximately 2.5 cm
diameter (large end)
-142-
1 Glass Tubing (I)
b. Construction
(1) Frame Support
wood (A)
ase (B)
. 7 cm diameter,
5 cm long
Nail two pieces of wood (A) to
a flat piece (B) to form a base
and uprights. Then nail two
more pieces of wood (A) to the
outsides of the uprights, as
shown, to form supports for
the can.
(2) Water Jacket
Outlet
•0
0-— Inlet
2.0
(Diameter)
Cut a hole approximately 2 cm
in diameter in the center of
the bottom of the can (D) .
Crimp the cut edges inward.
Cut a smaller hole, not quite
lcm in diameter, in the side
of the can near the bottom, to
accommodate the inlet tube.
Cut another small hole, not
quite 1 cm in diameter, in the
side of the can near the top,
for the outlet tube.
-143-
Watertight Seal
Glass
Tube (F)
Rubber
Tubing (E)
Insert each short piece of glass
tubing (F) into a short piece of
rubber tubing (E) . Insert each
rubber tube into one of the two
small holes in the can. If the
rubber tubes do not fit snugly
by themselves, make a water-
tight seal with candle wax or
epoxy resin .
Set the can in place in the
frame support. To secure it in
position, nail two pieces of
strapping (C) to the frame
support, one on each side of
the can.
(3) Condensing Pipe
Choose a one-hole rubber
stopper (H) that tightly seals
the hole in the bottom of the
water jacket can. Insert a
short piece of glass tubing (I)
part way through the stopper,
from the large end. Insert the
copper pipe (G) into the
stopper from the other end.
-144-
Copper Pipe (G)
Insert the condensing pipe into
the water jacket can through
the hole in the bottom of the
can. Push the stopper tightly
into the hole from the outside.
Seal with candle wax or epoxy
resin, if necessary, to produce
a watertight seam.
Glass Delivery
Tube (I)
c. Notes
(i) A plastic or rubber tube from a water source is attached to the inlet tube,
and another tube is attached to the outlet tube and led to a drain. A plastic or
rubber tube from the container in which water is boiled is connected to the free
end of the copper condensing pipe. Water vapor flowing through this tube will
condense and drip from the glass delivery tube at the bottom of the still, where
it can be collected.
(ii) This still is suitable for continuous operation, in order to produce dis-
tilled water for class use. In such a case, a large kettle should be used for
boiling the water, and a plastic or rubber tube can be attached to the delivery
tube and led to a storage container.
(iii) The size of the frame support for this still is determined by the size of
the can used for the water jacket. Its dimensions will vary, according to the
size of the can used.
-145-
C. ELECTRIC SEPARATOR
CI. Electrolysis Apparatus
(3) Collecting
Tubes
-s — (4) Frame
Support
(2) Electrodes
ontainer
a. Materials Required
Components
(1) Container
(2) Electrodes
(3) Collecting Tube
(4) Frame Support
b. Construction
(1) Container
Qu I tems Required
1 Glass Jar (A)
2 Stiff Wire, Insulated (B)
2 Thin Copper Sheet (C)
2 Masking or Adhesive Tape (D)
2 Test Tubes or Vials (E)
2 Wood Strips (F)
2 Wood Blocks (G)
2 Rubber Bands (H)
Dimensions
Approximately 100-200
ml capacity
Approximately . 1 cm
diameter, 25 cm long
1.5 cm x 3.0 cm
2 cm x 4 cm
Approximately 1 . 5 cm
diameter, 10 cm long
. 2 cm x 2 cm x 15 cm
Approximately 2 cm x
2 cm x 1.3 cm
Approximately . 2 cm
x 4 cm
Choose a small glass jar (A)
with a capacity of 100 - 200 ml,
or cut off the top of a jar to
-146-
(2) Electrodes
Solder Here
make a container of appropriate
size .
Strip about 1.5 cm of the insula-
tion off each end of the stiff,
insulated wire (B) . Solder one
end of each wire to a piece of
the copper sheet (C) , as shown.
When the solder has cooled,
roll the copper sheet (C) into
a spiral plate.
f%
^
Bend each of the stiff wires (B)
as illustrated. Make the large
loop long enough to fit over the
lip of the container (A) when
the flat 2 cm portion of the
wire is resting on the bottom of
the container .
Place the electrodes at opposite
sides of the container. Adjust
the bends, if necessary, so that
the plates of the electrodes are
about 1 cm apart . Secure the
wires to the outside of the
container with tape.
-147-
(3) Collecting Tubes
^
(4) Frame Support
slightly
Tdiameter
Glue the
r
Glue
narrower than t ,
of the col lee
two blocks tc
For the collecting tubes (E),
use small glass or plastic test
tubes or vials that are slightly
taller than the height of the
container (A) .
For the frame support, use two
thin, flexible wooden strips (F)
about twice as long as the
diameter of the container. Cut
two small wooden blocks (G) just
h e
diameter of the collecting tubes.
to one of
the strips, about 5 cm apart.
s
^CT
Glue
X
^TT-n
Glue the other strip to only
one of the blocks, as shown.
c. Notes
Hold the rubber bands (H) aside
until the apparatus has been
set up [see Note (i) ] .
(i) This apparatus is used to separate water into oxygen and hydrogen, which
are collected in the tubes. The container is filled with water sufficient to cover
the terminals by less than 1 cm. A little vinegar or washing soda (Na2C0o • IOH2O)
is added to the water to increase its conductivity. The collecting tubes are
filled with the same acidic (vinegar) or basic (Na2C03> solution. Then, with the
open end sealed with a thumb or forefinger, each tube is inverted and placed into
the container. The open end of the tube must be placed below the surface of the
solution before it is uncovered. Then, without being lifted out of the solution,
each tube is placed over one of the electrodes.
The frame support may be placed around the two collecting tubes. It is
secured tightly around the tubes with rubber bands at each end. With the tubes
-148-
thus supported, the frame is rested on the top of the container and the tubes are
carefully adjusted so that the open ends do not rest on the bottom of the container,
but are about 1 cm above the bottom and below the surface of the solution in the
container .
When the free ends of the electrodes are connected to three or more 1.5 volt
cells connected in series, sufficient current passes through the solution to break
down the water. Hydrogen is the gas generated at the negative plate (cathode) and
collected in the tube placed over that plate. Oxygen is generated at the positive
plate (anode) and is collected approximately one half as rapidly as hydrogen.
(ii) This apparatus is guite suitable for student use in the laboratory, as it is
simple to set up and requires little current. With three or more 1.5 volt cells,
the gases are evolved rapidly and the tubes can be filled in about 20 - 30 minutes.
(iii) Several factors enhance the efficient operation of this apparatus. The
small volume of solution used and the proximity of the plates reduce the amount of
resistance in the system and allow it to function on low current. If the plates
are cleaned after each use, the apparatus will also function more efficiently.
-149-
). CENTRIFUGAL SEPARATORS
Dl, Hand Drill Centrifuge
(1) Horizontal Bar
(2) Test Tube
Holder
'(3) Shaft
a. Materials Required
Components Qu I tems Required
(1) Horizontal Bar 1 Wood (A)
(2) Test Tube
Holder
(3) Shaft
Stiff Wire (B)
1 Nail (C)
1 Bolt (D)
b. Construction
(1) Horizontal Bar
Dimensions
2 cm x 2 cm x 32 cm
Approximately . 2 cm
diameter, 30 cm long
. 5 cm diameter,
18 cm long
Approximately . 5 cm
diameter, 2 cm long
Drill holes, approximately 0.4
cm in diameter, at each end of
the wooden bar (A) . Drill a
hole through the center of the
bar, as shown. Make the dia-
meter of this hole slightly
smaller than the diameter of
the nail (C) used for the shaft.
-150-
Then, drill a hole perpendicular
to and intersecting the hole in
the center of the bar. Make the
diameter of this hole slightly
smaller than the diameter of
the bolt (D) used to hold the
shaft in place.
(2) Test Tube Holder
Take a test tube of the size that
will be used in the centrifuge.
Wind one piece of heavy, stiff
wire (B) (coat hanger wire, for
example) around the test tube
two or three times. Make the
coil very snug around the test
tube so that the test tube lip
will not slip through it. Leave
a straight portion of about
8 - 9 cm at the top of the coil.
Bend the straight portion of
the wire at an angle to the
rest of the coil as shown.
About 3 cm from the coil, bend
the wire again, at right angles
to the upright portion.
-151-
Fit the free end of the wire
into one of the end holes in
the horizontal bar. Check to
see that the fit is loose
enough for the holder to swing
easily. Then bend the excess
wire down, as shown, to secure
the holder in the horizontal
bar.
Repeat this procedure for the
construction of the second test
tube holder.
(3) Shaft
©
fc
Carefully thread the short bolt
(D) into the center, horizontal
hole in the horizontal bar.
Then unscrew it halfway. Fill
the nail hole (vertical hole)
with epoxy glue and tap the
nail (C) into the hole. Tighten
the bolt against the nail and
coat the threads of the bolt
with epoxy glue .
t>J
c . Notes
(i) A precipitate formed by a chemical reaction in a test tube will eventually
settle to the bottom because of the force of gravity acting upon it. The time
required for a given precipi-
tate to settle is dependent on
several factors; among these
are the volume, density, and
particle size of the precipi-
tate. Spinning such material in
a test tube in a centrifuge
reduces this duration by creat-
ing a strong centrifugal force,
which causes the heavier
precipitate to settle to the
Precipitate
-152-
outside of the centrifuge. When the test tube holders are free to pivot outward,
as in this centrifuge, the test tubes will assume a nearly horizontal position
when the centrifuge is in rapid motion. Thus, the bottom of the test tube
becomes the "outside" of the centrifuge, and precipitate is pulled to the bottom of
the tube.
(ii) To use this centrifuge, place an appropriately sized test tube containing
material to be centrifuged through one of the wire holders. To balance the centri-
fuge, place a test tube with an equal volume of water in the other holder. Take
care to insure that the test tubes are securely held in place by the holders.
Seal both test tubes with corks or stoppers to prevent spillage. Fix the end of
the shaft firmly in a hand drill. Clamp the drill handle tightly in a heavy vise,
stand at arm's length from the drill, and turn the handle of the drill. The centri-
fuge will spin, causing the precipitate to collect at the bottom of the test tube.
To stop the centrifuge, let go of the drill handle and allow the centrifuge to
continue to spin until it comes to a gentle stop. Another way to stop the centri-
fuge is to turn the drill handle more and more slowly until it is brought to a
gentle stop. Sudden stops, which will shake up the precipitate, are to be avoided.
(iii) If a vise is not available, the drill may be held at arm's length from the
body while the centrifuge is spun.
(iv) This centrifuge is capable of being spun at 300 - 500 revolutions per
minute. It was tested with several precipitates, such as CaC03 and AgN03, and was
found to reduce settling time from several hours (gravity) to less than one minute.
(v) This centrifuge, whether clamped in a drill or held at arm's length, must
be used with extreme care since the test tubes swing close to the user. A safer,
more permanent centrifuge, which incorporates this centrifuge as its rotating
assembly, is described in the following section.
•153-
D2 . Centrifuge
a. Materials Required
Components
(1) Base
Qu I tems Required
1 Wood (A)
3 Wood (B)
2 Wood (C)
Dimensions
4 cm x 9 cm x 30 cm
2 cm x 5 cm x 30 cm
2 cm x 5 cm x 25 cm
-154-
(2) Wheel
(3) Axle
(4) Head
1 Wood (D)
1 Wood (E)
1 Wooden Spool (F)
2 Washers (G)
1 Screw (H)
1 Screw (I)
1 Rubber Strip (J)
1 Wood (K)
1 Wooden Spool or Dowel (L)
3 Finishing Nails (M)
1 Screw (N)
2 Washers (0)
1 Nail (P)
1 Bolt (Q)
1 Rubber Strip (R)
2 Metal Strapping (S)
1 Wood (T)
2 Stiff Wire (U)
Bolt (V)
Approximately 3 cm x
3 cm x 1 cm
1 cm x 15 cm x 15 cm
Approximately 3 cm x
3 cm x 3 cm
Approximately D . 8 cm
inside diameter, 2.0
cm outside diameter
Approximately . 6 cm
diameter, 6 . cm long
Approximately 3 cm
long
1 cm x 50 cm
4 cm x 4 cm x 16 cm
3 cm diameter,
3.5 cm long
Approximately 5 cm
long
Approximately . 6 cm
diameter, 6 . cm long
Approximately . 8 cm
inside diameter, 1.5
cm outside diameter
. 5 cm diameter,
18 cm long
Approximately . 5 cm
diameter, 2 cm long
3.5 cm x 10 cm
11 cm x 1 cm
2 cm x 2 cm x 32 cm
Approximately . 2 cm
diameter, 30 cm long
Approximately . 5 cm
diameter, 2 cm long
b. Construction
(1) Base
With nails or glue and screws,
secure the thick piece of wood
(A) to two pieces of wood (B)
as shown to form the feet and
bottom of the base. Drill a
hole approximately 0.5 cm in
diameter at each end of the
feet (B) .
Wood (B)
-155-
Next, nail or glue and screw the
third piece (B) to the bottom of
the base, in an upright position
as shown. Secure the two
shorter uprights (C) in position
as shown. Glue the small piece
of wood (D) to the center of the
horizontal board. When the glue
has dried, drill a hole about
0.5 cm in diameter through the
small piece of wood (D) and a
centimeter or so into the base
(A) .
(2 ) Wheel
Inscribe a circle in the thin
wooden square (E) . Carefully
cut out the circle. Drill a
hole, 0.7 cm diameter, through
the center of the circle.
Wood (E)
'Rubber Strip (J)
Fasten the strip of rubber
sheeting (J) (e.g., from a tire
inner tube) to the circumfer-
Handle (F) ence of the wheel with glue and
small nails with heads.
With the shorter screw (I),
fasten the wooden spool (F)
loosely to the wheel about
halfway between the center and
edge of the wheel. The handle
must be free to rotate around
the screw.
-156-
Wheel
(3) Axle
Nail Hole
Bolt Hole
Mount the wheel to the base by
inserting the long screw (H)
through a washer (G) , through
the wheel, then through the
second washer (G) . The holes in
the wheel and washers should be
slightly larger in diameter than
the screw (H) . Finally, turn
the screw firmly into the small
piece of wood (D) on the hori-
zontal board of the base. Make
certain that the wheel will
rotate freely around the screw
without wobbling.
For the upper section of the
axle, use the wooden block (K)
or dowel. Drill a hole approxi-
mately 0.4 cm in diameter and
approximately 5 cm deep into
the center of one end of the
block. Then drill a second
hole, about 2.5 cm from the end,
at a right angle to and inter-
secting the first hole. Make
the hole about 0.4 cm in
diameter, or just a little
smaller than the bolt (Q) which
is to be threaded into it.
Flatten the end of a large
nail (P) by hammering it on a
metal block or anvil.
-157-
o
Nail (P) With
Head Removed
Bolt (Q)
Carefully thread the bolt (Q)
as far as possible into the
bolt hole in the axle, then
unscrew it halfway. Fill the
nail hole with epoxy glue, and
tap the nail (P) into the hole.
Tighten the bolt against the
nail, then coat its threads
with epoxy glue. Finally, cut
the head off the nail.
For the lower section of the
axle, use a wooden spool (L)
from which the thread has been
removed, or a 3 cm diameter
dowel. Cut the spool or dowel
to a height of about 3.5 cm.
Fasten a strip of rubber sheet
(R) around the outside, just as
for the wheel. Enlarge the
hole in the spool to about 0.7
cm diameter.
-15?
Finishing
Nail (M)
Washer (0)
Fit one washer (0) on the top
of the spool, aligning the holes
of spool and washer. Drive
three small finishing nails (M)
into the top of the spool, out-
side the washer. Let approxi-
mately 3 cm of nails protrude
from the top of the spool, and
cut off their heads.
Base
Uprights
Locate the position of the axle
by setting the spool on the
horizontal board (A) of the
base such that the rubber strip
on the spool presses firmly
against the rubber strip on the
wheel. Mark the position of
the center of the spool, and
drill a small hole at that
position.
Overhead View of Base, Wheel
and Axle Location
-159-
( N )
Washer (0)
Washer (0
Mount the spool (L) on the
horizontal board (A) of the
frame by passing a long screw
(N) through the washer (0) and
spool (L) ; then through a second
washer (0) , and into the hole in
the base. Turn the screw
firmly into the horizontal
board, so that the spool is
free to rotate. In addition,
the edge of the wheel must rub
the edge of the spool firmly
enough so that when the wheel
turns, the spool also rotates.
Strapping
(S)
Construct strapping braces for
the axle as follows: Drill a
hole 0.8 cm in diameter in the
center of one of the pieces of
metal strapping (S) . Nail this
piece to the two shorter up-
rights (C) of the base such
that the hole in the strapping
is directly over the center of
the spool on the base below.
Drill a similar hole near one
end of the other piece of
strapping (S), and nail it, as
shown, to the taller upright of
the base (B) such that its hole
is directly over the hole in
the strapping below it. Trim
off any excess .
ro
©
Slip the nail end of the upper
section of the axle through the
holes in the strapping braces.
Rest the other end of the upper
section evenly on the tops of
the three nails in the spool,
and then drive the upper section
into the nails with a hammer so
that the spool and upper sec-
tion will form a continuous
solid piece. However, do not
drive the upper section so far
down that its end will hit the
top of the screw and prevent
the entire axle from turning.
If this operation has been done
correctly, the axle will turn
when the wheel is rotated.
Head
c. Notes
Prepare the horizontal bar and
test tube holders according to
directions given for the Hand
Drill Centrifuge, VI/D1, using
the wood (T) and stiff wire (U)
Secure the nail of the axle to
the centrifuge head according
to directions given in VI/D1
with the bolt (V) .
(i) The centrifuge should be bolted or clamped to the table top before using.
(ii) To use this piece of apparatus! the substance to be centrifuged is placed
in an appropriately sized test tube. A second test tube is filled with an egual
amount of material to be centrifuged or an equal volume of water. Each test tube
is placed in one of the holders and checked to see that they will not slip out
through the holder. Both test tubes are sealed with stoppers. Stand at arm's
-161-
length from the centrifuge and turn the wheel, first slowly, then more and more
rapidly. The tubes will be spun about in a nearly horizontal position. Do not
try to stop the centrifuge suddenly by holding the wheel stationary; either let go
of the wheel and allow the centrifuge to come to a gentle stop, or turn the wheel
more and more slowly until the centrifuge is brought to a gentle stop.
(iii) Matched pairs of test tube holders of various sizes may be constructed and
used interchangeably in the same centrifuge head, if desired.
(iv) When the wheel of this centrifuge is turned rapidly, about 150 turns per
minute, for example, the centrifuge head spins at nearly 500 revolutions per
minute .
-162-
VII. GAS GENERATORS
The apparatus used in the production of gases has been placed in two sections, one
of which contains the complete apparatus for gas generation while the second section
contains two devices useful in collecting gases.
A. GAS GENERATORS
Three types of generators will be given: simple devices for which no special
equipment is required; and an inexpensive version of Kipp's gas generator.
B. ACCESSORIES
Included here are the beehive shelf and metal sheet shelf.
-163-
A. GAS GENERATORS
Al . Simple Gas Generator and Collecting Apparatus
(1) Generator
(2) Delivery Tube
(3) Collecting
Apparatus
a. Materials Reguired
Components
(1) Generator Tube
(2) Delivery Tube
(3) Collecting
Apparatus
b. Construction
(1) Generator Tube
q u Items Reguired
Test Tube or Flask (A)
1-Hole Rubber Stopper (B)
Glass Tubing (C)
Rubber or Plastic
Tubing (D)
Glass Tubing (E)
Test Tube, Flask, or
Bottle (F)
Bowl or Pan (G)
Dimensions
Capacity at least
50 ml
To fit generator
tube (A)
0.5 cm diameter,
5-10 cm long
To fit glass tubing
(C and E), 30 cm long
0.5 cm diameter,
15-25 cm long
Capacity at least
50 ml
250 ml or greater
capacity
For the generator tube, use a
hard-glass test tube or flask
suitable for heating (A) .
Secure test tube in a slanted
position with an appropriate
clamp or support (IV/B5 or B6) .
-164-
(2) Delivery Tube
(3) Collecting Apparatus
Fit the generator tube with a
one-hole rubber stopper (B) .
Insert the shorter glass tube
(C) through the one-hole rubber
stopper. Connect the rubber or
plastic tubing (D) to the free
end of the glass tube (C) .
Bend the longer glass tube (E)
at a 90' angle or less, and
connect it to the flexible
tubing (D) .
Select a large test tube,
flask, or bottle (F) . Fill with
water, cover the opening, and
invert in a bowl or pan of
water (G) so that the water is
held in the bottle (F) . Uncover
the opening and place the free
end of glass tubing (E) into the
mouth of the collecting tube.
c. Notes
(i) This apparatus is suitable for student use in generating small amounts of
gases which are insoluble or only slightly soluble in water.
(ii) Small amounts of reactants are placed in the generator tube and carefully
heated (if heating is required) . The gas generated passes through the delivery
tube, and is collected by displacing the water in the collecting tube.
A2 . Flask Generator
-165-
(1) Generator
Flask
(2) Funnel
) Delivery Tube
a. Materials Required
Components
(1) Generator Flask
(2) Funnel
(3) Delivery Tube
b. Construction
(1) Generator Flask
(2) Funnel
q u Items Required
1 Flask or Bottle (A)
1 2-Hole Rubber Stopper (B)
1 Long-necked Funnel (C)
2 Glass Tubing (D)
1 Plastic or Rubber
Tubing (E)
Dimensions
250 ml capacity or
larger
To fit flask (A)
Approximately 10 cm
diameter (large end)
0.5 cm diameter,
15-25 cm long
To fit glass tubing,
approximately 30 cm
long
(3) Delivery Tube
Support the flask or bottle (A) ,
if necessary, in a suitable sup-
port. Fit the flask with a two-
hole rubber stopper (B) .
Select a funnel (C) with a
sufficiently long neck to reach
nearly to the bottom of the
flask (A) . Carefully push the
funnel neck through one of the
holes in the stopper (B) .
Make a 90' bend in each piece
of glass tubing (D) . Connect
-166-
these with flexible tub tng (E)
Insert one of the glass tubes
into the second hole of the
rubber stopper (B) .
c. Notes
(i) This apparatus is used in conjunction with the collecting apparatus just as
described in the previous section (VII/A1).
(ii) This device is generally chosen when the gas generating reaction involves
a solid (such as zinc) and a liguid (such as dilute sulfuric or hydrochloric acid) .
The solid is placed in the bottom of the generator flask, then the rest of the
apparatus is placed in position. When the collecting bottle is in place, the
liguid reagent is added through the funnel. Thus, the reaction does not begin
until the apparatus is sealed. Additional liguid can be added to the flask with-
out dismantling the apparatus.
(iii) If a funnel made from a cut-down bottle is used (V/A3), it will be necessary
to adapt the construction of
this item slightly . Connect
such a funnel to the flask (A)
with a long piece of glass
tubing running through the
stopper (B) and a one-hole
stopper fitted into the funnel.
-167-
A3 . Kipp ' s Generator *
(4) Funnel
3) Gas Delivery
Tube
2) Reaction
Flask
(1) Acid
Container
*Adapted from C S. Rao (Editor), Sci ence Teachers' Handbook, (Hyderabad, India:
American Peace corps, 1968), pp 174-175.
-168-
a. Materials Required
Components q u
(1) Acid Container 1
(2) Reaction Flask
O) Gas Delivery
Tube
(4) Funnel
Items Required
Glass Jar (A)
Rubber Stopper (B)
Plasticine (Modeling
Clay) or Pitch (C)
Glass Bottle (D)
1 or 2-Hole Rubber
Stopper (E)
Glass Tubing (F)
Rubber Tubing (G)
1-Hole Rubber Stopper (H)
Glass Tubing (I)
Rubber Tubing (J)
Pinch Clamp (K)
Glass Bottle (L)
1-Hole Rubber Stopper (M)
Dimensions
Capacity approxi-
mately 500 ml
Approximately 2 . cm
diameter (large end)
4cmx4cmx4cm
Capacity approxi-
mately 500 ml
To fit bottle (D)
Approximately . 7 cm
diameter, 30 cm long
1 . cm diameter,
3 cm long
Approximately 2 . cm
diameter (large end)
. 7 cm diameter,
5 cm long
1 . cm diameter,
30 cm long
(IV/A4)
Capacity approximately
1 liter
To fit bottle (L)
b. Construction
(1) Acid Container
Select a low, wide-mouth jar
with a capacity of about 500 ml
(A) . Drill a hole in the side
of the jar, just above the
bottom, (I/E2) . Enlarge the
hole, by filing with a round
file, to a diameter of 1.7 -
1.8 cm. Seal this hole with a
solid rubber stopper (B) .
-169-
(2) Reaction Flask
Stopper (H)
Bottle (D)
0.8 - 0.9
Diameter
1.7 - 1.8
Diameter
For the reaction flask, choose
a narrow-necked bottle (D) that
will just fit into the neck of
the acid container (A) . Drill
a hole in the center of the
bottom of the bottle (D) , and
enlarge the hole to a diameter
of 0.8 - 0.9 cm. Drill a
second hole in the side near
the bottom. Enlarge this hole
to a diameter of 1.7 - 1.8 cm.
Fit a one-hole rubber stopper
(H) into the side hole.
(E)
Select a stopper (E) that fits
the neck of the bottle (D) . If
it is a one-hole stopper with
a round file, enlarge the hole
in the stopper to about two to
three times its normal diameter.
Fit this stopper into the neck
of the bottle. If a two-hole
stopper is available, make no
alterations, and fit the
stopper into the neck of the
bottle (D) .
-170-
o
M
"1-
4 - 5
U
Rubber Tubing (G)
Glass Tubing (F)
Fire polish (I/D4) both ends of
the glass tubing (F) . Insert
one end into the short length
of rubber tubing (G) . Allow
4 - 5 cm of glass tubing (F) to
protrude beyond the rubber
tubing (G) .
Insert the long end of the
glass tubing (F) into the
bottle (D) , from the bottom.
Fit the end through the en-
larged hole of the stopper (E) ,
and carefully push and twist
until the rubber tubing (G)
around the glass tightly seals
the hole in the bottom of the
bottle (D) .
Set the reaction flask (D) ,
neck down, into the neck of the
acid container (A) . Adjust and
cut the glass tubing (F), if
necessary, so its lower end is
about 0.5 cm from the bottom of
the acid container (A) .
Roll the modeling clay (plasti-
cine) (C) into a long cylinder
and wrap it around the seam
between reaction flask (D) and
acid container (A) . Press the
clay firmly in place to make an
airtight seal.
-171-
(3) Gas Delivery Tube
(4) Funnel
^s
/
"\
s
\
Bottle (L)
+
Cut
C. Notes
Insert a short piece of glass
tubing (I) into the stopper in
the side of the reaction flask.
Attach rubber tubing (J) to the
other end of the glass tube.
Use a wooden pinch clamp (K)
(IV/A4) or other suitable clamp
to close the rubber tubing.
Construct a large funnel with a
capacity equal to that of the
acid container by cutting off
the bottom third of a narrow-
necked bottle (L) (I/F2) .
Smooth the rough cut edge of
the funnel with emery cloth.
Select a one-hole rubber
stopper (M) to fit the funnel
neck. Insert the glass tube
(F) from the reaction flask (D)
into the stopper (M) .
Invert the funnel (L) and fit
its neck tightly over the
stopper (M) .
Support the funnel in a ring
stand (IV/B5)or other suitable
holder .
(i) To complete the gas generating apparatus, the gas delivery tube of the
Kipp's Generator must be connected to a suitable collection device such as that
described in VII/Al_or the aspirator described in V/A8.
(ii) The solid reactant, such as zinc chips is added to the reaction flask (D)
through the hole in the side. The solid will sit, for the most part, on the
stopper (E) in the neck of the flask. The stopper (H) and gas delivery tube are
then securely replaced in the reaction flask, and all connections and seals are
checked to insure that they are gastight. Then the liquid reagent, such as
6M hydrochloric acid, is poured into the funnel (L) .
When the pinch clamp (K) is removed from the gas delivery tube, the acid
will flow into the acid container (A) . As the acid level rises above the neck
-172-
of the reaction flask (K) , it will flow into the reaction flask through the
enlarged or second hole of the stopper (E) and will react with the solid to pro-
duce a gas (hydrogen, in this example) . The gas will pass through the delivery
tube to the collecting vessel.
(iii) The reaction can be stopped without removing any of the reactants or
dismantling the equipment . When the gas delivery tube is closed with the pinch
clamp, the pressure of the gas accumulating in the reaction flask will force the
acid out of the reaction flask and back into the acid container until it is no
longer in contact with the solid. Some of the acid will also be forced back up
the glass tube and into the funnel. The funnel must therefore be large enough
to safely contain a large volume of acid that might be backed up.
To restart the reaction, the delivery tube is opened, and acid again flows
into the acid container and. reaction flask to evolve more gas.
(iv) This device is suitable for evolving large quantities of a gas for class
use, or as a demonstration. it should be possible to build a larger model, but
experimentation with the size relationships between the funnel, reaction flask,
and acid container will be necessary.
(v) Ifthe Kipp's Generator is to be employed for continuous classroom use, a
safety tube and funnel may be
Funnel
Safety Tube
Bottle-
Substitutes for
Funnel (L)
Reaction
Flask (D)
substituted for the large
funnel to prevent the escape of
unpleasant or undesirable acid
fumes. A piece of glass
tubing, approximately . 7 cm
diameter and 35 - 40 cm long,
is bent as shown. This is
connected, by means of a
rubber stopper at the upper
end, to a funnel. A bottle
with a hole drilled in the
bottom is substituted for the
large funnel (L) , and the lower
end of the safety tube is
connected to this bottle with a
one-hole rubber stopper or short
piece of rubber tubing.
The whole apparatus must be
supported in a stand or frame
of some kind.
-173-
B. ACCESSORIES
11. Beehive Shelf
0) Can
a. Materials Required
Components
(1) Can
b. Construction
(1) Tin Can Shelf
Qu I tems Required
1 Tin Can (A)
Dimensions
9 cm diameter x
5 cm high
Select a short tin can with
one end removed (A) . Cut a
V-shaped notch about 1 cm high
in the side of the can. Drill
a hole 1.5 cm in diameter in
the center of the end of the
can. Varnish the can.
c. Notes
(i) The beehive shelf is placed in the bottom of a pan of water. A gas collect-
ing tube or jar, filled with water as described in VII/A1, is inverted on the
shelf, with the mouth of the jar over the hole in the shelf, The gas delivery
tube is then inserted through
the notch of the shelf, up
through the hole, and into the
neck of the collecting jar.
From Gas
Generator
Beehive
Shelf
-174-
B2 . tfetal Sheet Shelf
o o o
Shelf
a. Materials Required
Components
(1) Shelf
b, Construction
(1) Metal Sheet Shelf
Qu I tems Required
1 Metal Sheet (A)
Dimensions
Approximately 0.05 cm
thick, 8 cm x 30 cm
Cut the metal sheet from heavy
aluminum sheeting or a tin can.
Cut three holes, 1.5 cm in
diameter, in the sheet (A) as
shown. Bend the edges up as
shown. Finally, make curved
bends approximately 1 cm from
each end.
c. Notes
(i) This shelf may be hung from the sides of a rectangular pan measuring from
12 to 20 cm wide. The shelf must be covered with water. Collecting bottles,
filled with water, are inverted over the holes and set on the shelf.
-175-
VIII. METALWARE AND CLEANER
A. METALWARE
The items in this section are small pieces of metalware which can be constructed
from scrap strapping, wire and the like. Items which can be improvised from normal
household items, such as knives, have not been included.
B. CLEANER
This item can be used to clean the test tubes utilized in chemistry.
Al. Flame Test Wire
-17(
A . METALWARE
(1) Wire
a. Materials Required
Components
(1) Wire
b. Construction
(1) Wire
c. Notes
Qu I tems Required
1 Transfer Loop
Dimensions
BI0L/VII/A3
SeeBI0L/VII/A3 for construc-
tion details .
(i) Use this wire to flame test compounds. Simply get a small amount of the
chemical caught in the wire loop and hold it in a hot flame to observe the color
of the flame.
-177-
A2 . Deflagrating "Spoon"
(1) Spoon
a. Materials Required
Components
(1) Spoon
b. Construction
Qu I tems Required
1 Metal Strapping (A)
Dimensions
(1) Spoon
Bend Slightly
About 10 cm x 3 cm
Carefully sand off all the
paint from one end of the
metal strapping (A) so that
there is only bare metal. Make
a slight bend in this end about
1.0 cm from the end.
Sand Both Sides
c . Notes
(i) To use the deflagrating spoon, place a small amount of the chemical to be
heated on the bent portion of the strapping. Hold the spoon in a holder (e.g.,
IV/A4 ) . and hold the chemical in the flame of a burner until it burns or melts.
The deflagrating spoon is used mainly in doing flame tests on unknown compounds.
(ii) When the end of the spoon becomes contaminated, either clean it with sand-
paper or simply cut it off, sand the new end, and bend it as before.
A3. Spatula
C
\.
-17£
(1) Spatula
a. Materials Required
Components
(1) Spatula
b. Construction
(1) Spatula
c
^«w
Handle
Notes
Qu I tems Required
1 Tin Can or Strapping
Wire (A)
=o
\
scoop
Dimensions
20.0 cm long,
3.0 cm wide
Cut a piece of tin can metal
(A) or a piece of wire
strapping to the desired length
and width. Cut the metal to
the shape illustrated.
Make a depression in the scoop
by hammering a steel ball in
the circle.
Depress the center of the
handle slightly for easier
handling.
(i) This spatula may be converted to a deflagrating spoon by bending the
handle backward at a 90' angle with the shaft and bending the scoop forward at a
90' angle with the shaft.
-179-
B. CLEANER
Bl. Test Tube Cleaner or Spatula
c
;i) Handle
(2) Cleaner
a. Materials Required
Components
(1) Handle
(2) Cleaner
b. Construction
(1) Handle
£
Qu I tems Required
1 Wooden Dowel (A)
1 Piece of Rubber Inner
Tube (B)
Dimensions
25 cm long
5 c m x 5 c m
\
Use a piece of wooden dowel (A)
about 2 5 cm in length. Make
a slit about 2 . cm long in
the center of one end of the
handle.
Slit
(2) Cleaner
Cut Along
This Line
Cut a triangular piece of
rubber (B) about 5 . cm long
from a discarded inner tube.
Insert this in the slit made
in the handle. Drive a small
nail through the handle and
cleaner to hold them in place,
if necessary.
-180-
IX. HEATERS AND DRYERS
The apparatus in this section has been divided into two categories, as follows:
A. DRYERS
Dryers are devices used to remove the moisture content from chemical compounds.
B. HEATER
This is a device that is intended to produce a heat intense enough to incinerate
precipitates .
-181-
A. DRYERS
Al . Dessicator
!>
(3) Tubing
(2) Dryer
(1) Container
a. Materials Required
Components
(1) Container
(2) Dryer
(3) Tubing
q u Items Required
1 Glass Jar (A)
1 Lid (B)
1 Small Tin Can (C)
1 Wire Mesh (D)
Calcium Chloride or
Silica Gel (E)
1 Rubber Tubing (F)
1 Glass Tube (G)
1 Screw Clamp or Pinch
Clamp (H)
Dimensions
Capacity 200 ml
or more
To fit jar (A)
To fit inside jar (A)
To cover tin can (C)
1 cm diameter,
15 cm long
0.7 cm diameter,
5 cm long
(IV/A4 or A5) .
-182-
b. Construction
(1) Container
(2) Dryer
Glass Tube (G)
Rubber Tubing (F)
Select a jar (A) with a screw
top (B) and a very wide mouth.
Cut a hole slightly less than
1.0 cm in diameter in the center
of the jar lid (B) .
Take a short tin can (C) which
fits easily into the jar, or
cut a taller can to a height
of 2 - 3 cm.
Place a drying agent, such as
calcium chloride (CaCl ? )
pellets or silica gel (C) in
the can. Cover the can with
wire mesh (D) and set it in
the bottom of the jar (A) .
Cut a section of about 3 cm
from the piece of rubber
tubing (F) . Insert one end
of the glass tube (G) all the
way into this short piece of
rubber tubing. Insert the
other end of the glass tube (G)
into the longer section of
rubber tubing. Push the
shorter piece of rubber tubing,
with the glass tube inside, into
the hole in the top of the jar
lid (B) . Seal the tubing into
the hole in the jar with cement,
if necessary, to make an
airtight seam. Seal the long
rubber tube with a pinch clamp
(IV/A4) or screw clamp (IV/A5) .
C. Notes
(i) Powders or substances to be kept free of moisture are placed in containers
inside the dessicator, and the top is sealed. The rubber and glass tube arrangement
permits a partial vacuum to be formed in the dessicator if it is used in
conjunction with a vacuum pump.
-183-
A2, Drying Tower
Jl) Container
(2) Tubing
a. Materials Required
Components
(1) Container
(2) Tubing
b. Construction
(1) Container
g u Items Required
1 Glass Bottle (A)
1 1-Hole Stopper (I
3 Rubber Tubing (C)
2 Glass Tubing (D)
Dimensions
Capacity approximately
300-400 ml
To fit bottle (A)
1 cm diameter,
5 cm long
0.7 cm diameter,
5 cm long
Drill a hole just slightly
smaller than 1.0 cm in the side
of the bottle (A) near the
bottom (I/E2) . Fit the bottle
(A) with a one-hole cork or
rubber stopper (B) .
-184-
(2) Tubing Insert one of the pieces of
glass tubing (D) into the one-
hole stopper, and push a piece
of rubber tubing (C) on to the
other end of the glass tube.
Insert one piece of rubber
tubing (C) into the hole in the
bottle (A) , and cement it in
place to make an airtight seal.
Push the second piece of glass
tubing (D) into the rubber
tubing (C) , and connect the last
piece of rubber tubing (C)
tothe glass tube (D) .
c . Notes
(1) This apparatus is used in removing moisture from gases. For example,
moisture can be eliminated f rom H q n CI-,, an d S0 9 by filling the drying
Z Z Z Z z
tower with calcium chloride or other drying agent and connecting it by means
of the tubing connections at top and bottom, between the gas generator and
collecting device. As the gas passes through the drying tower, moisture is
absorbed by the drying agent.
A3. Electric Lamp Dryer
-185-
(2) Lamp
(1) Support
a. Materials Requir
ed
Components '
Qu
Items Required
(1) Support
1
1
1
Wood (A)
Wood (B)
Wood (C)
2
Wood (D)
Dimensions
30 cm x 30 cm x 1 cm
1 cm x 2 cm x 32 cm
1 cm x 2 cm x 18 cm
4 cm x 4 cm x 2 cm
( 2 ) Lamp
Lamp Socket (E)
Insulated Electrical
Cord and Plug (F)
Incandescent Bulb (G)
Large Staples or
Thin Nails (H)
Bolt (I)
1
Nut (J)
1
Wire Mesh (K)
1
Thin Wire (L)
1
Aluminum Foil
100 watts
Approximately
0.8 cm x 3 cm
To fit bolt (I)
20 cm x 2 cm
15 cm
20 cm x 2 cm
-186-
b. Construction
(l)Support
Construct the support as
illustrated. Use glue and
screws to secure the parts
(A) , (B) , (C) and (D) to
one another .
(2) Lamp
Secure the lamp socket (E) to
the top horizontal bar (C)
with the nut (J) and bolt ( I )
Attach the electrical cord,
with plug attached (F), to the
socket (E) . Run the wire along
the top bar (C) and down the
back of the vertical support (B)
Secure the cord in position
with large staples (H), bent
nails, or tape.
-187-
From the wire mesh (K) , cut a
circle. Cut out and remove the
shaded portion as shown. cut
a similar but slightly larger
shape from the aluminum foil (M)
Curve the wire mesh (K) into a
cone with an open end that will
fit over the base of the
incandescent bulb (G) , and
secure the cut edges together
by threading the thin wire (L)
in and out of the wire mesh.
Cover the inside of the wire
mesh cone (K) with the foil (M) ,
shiny side to the inside of
the cone. Secure the foil
reflector (M) to the wire
mesh (L) by bending the foil
edges around the wire mesh cone.
Notes
Slip the small end of the
reflector over the neck of
the bulb (E) and screw the
bulb into the socket (E) .
(i) The light provides a heat source for drying precipitates which are placed
in shallow containers, watch glasses (V/A5) or petri dishes (V/A6) .
(ii) Experimentation in the use of the dryer might include varying the size of
the reflector, distance of the bulb from the material, wattage of bulb and
number of bulbs used.
A4. Sand Bath
(1) Can
a. Materials Required
Components
(1) Can
b. Construction
(l)Can
c. Notes
Qu Items Required
1 Larqe Tin Can (A)
Sand (B)
Dimensions
15-20 cm diameter
Use a larqe, shallow tin
can (A) as a container, or
cut a larqer can to a
heiqht of about 5 cm. Fill
the container with sand (B) .
(1) Solutions or precipitates that must be evaporated or dried slowly may be
placed in shallow containers, watch qlasses, or petri dishes which are rested on
the sand, The sand bath is then rested on a tripod (IV/B3), heatinq stand (IV/B4)
or other suitable support and slowly heated with an alcohol or qas burner.
-189-
A5. Water or Steam Bath
;i) Container
a. Materials Required
Components
(l)Container
b. Construction
(1) Container
C. Notes
Qu Items Required
1 Tin Can (A)
Dimensions
Capacity approximately
150-300 ml
Use an empty, clean tin can
(A) for the container. Fill
it about 2/3 full of water.
(i) Use of the water bath is a safe way to heat materials that must not, for
technical or safety reasons, be heated above about 100'C. Test tubes containing
material to be heated are placed in the water bath. The water bath is rested on
asuitable support and heated with an alcohol or gas burner. Materials heated
in the test tubes will be heated to a temperature not higher than the boiling
point of the water.
(ii) The water bath may be converted to a steam bath by the addition of a row
of holes punched or drilled around the can near the top. The can is filled about
1/3 full of water, and a
petri dish (V/A6) or watch
glass (V/A5) containing
material to be heated is
rested on top.
■190-
The steam bath is rested on a suitable support and heated; as the water boils,
the steam will heat the material in the petri dish or watch glass and will be
able to escape through the holes in the top of the can.
-191-
B. HEATER
Bl. Blowpipe for Charcoal Block
(I) Blowpipe
(2) Charcoal Block
a. Materials Required
Components
(1) Blowpipe
(2) Charcoal Block
b. Construction
(1) Blowpipe
(2) Charcoal Block
Notes
Qu
:
Items Required
Rubber Tubing (A)
Glass Tubing (B)
Charcoal Block (C)
Dimensions
Approximately 1 . cm
diameter, 10 cm long
Approximately . 7 cm
diameter, 20 cm long
Heat the glass tubing (B)
near one end and bend it
slightly as shown. Then
heat it again, just past
the bend, in order to draw
it out to form a nozzle.
Fit the rubber tubing (A)
over the other end of the
glass tube (B) .
Use a lump of charcoal (C)
as a heat source.
(i) This item is used to create a concentrated heat source by blowing through
the blowpipe onto the charcoal ember.
-192-
X. MOLECULAR MODELS
Four types of models to assist in the instruction and understand 1'ng of molecular
structure are described.
A. SPACE-FILLING MODELS
These roughly represent relative sizes and positions of atoms within a molecule.
B. SKELETAL MODELS
These models more accurately represent atomic radii and bond angles than do those
in the previous section.
C. CRYSTAL MODELS
These are three-dimensional models that represent shape and atomic packing within
crystals .
D. KINETIC-MOLECULAR MDDEL
This two-dimensional model demonstrates the kinetic theory of matter.
Al. Ball-and-Stick Models
193-
A. SPACE-FILLING MODELS
3) Flexible
Connector
C 2 H 2
a. Materials Required
Components
(1) Ball
g u Items Required
1 Block of Styrofoam Plastic
or Foam Polystyrene (A)
1 Electric Bottle Cutter (B)
1 Thin Nichrome Wire (C)
Dimensions
Approximately
4 cm x 10 cm x 10 cm
(I/F2)
0.02 cm diameter,
35 cm long
-194-
(2) Rigid Connector 1
(3) Flexible Connector 1
b. Constructi on
Box of Toothpicks (d) Approximately 250
Package of Pipe C eaners (E) Approximately 25
(1) Ball
Terminals of Electric
Bottle Cutter (B)
T
Thin Nichrome
Wire (C)
Styrofoam (A)
Construct the electric bottle
cutter (B) according to
directions given in (I/F2) .
Substitute the thin nichrome
wire (0.02 cm diameter) for
that described and stretch
it tightly between the terminals,
Connect the terminals to a six
volt battery or a transformer
that steps line current down
to about six volts.
Form the Styrofoam (A) into
small balls, First, cut the
block into cubes, determining
the sizes according to the
element each represents:
H - 1 . 5 cm on a side
C - 3 c m " " "
- 3 c m
Si - 4 cm
To cut a precise straight line,
brace a large wooden block
against the base of the bottle
cutter, with one edge as far
from the taut wire as the width
of the desired cut. Push the
Styrofoam block (A) down on
the hot, taut wire to slice
it, holding it against the
wooden block which acts as a
guide.
Wood Block
-195-
Carefully cut the corners off
each cube to approach the
shape of a sphere.
(2) Rigid Connectors
Sigma Bonds
Hydrogen
(3) Flexible Connectors
Pi Bond
Last, shape the trimmed cubes
with the fingers more exactly
into spheres.
For clarity in the finished
models, paint the balls with
tempera (poster paint) to
which a small amount of
dissolved soap has been added.
Use the following colors to
represent :
H - white
C - black
- red
Stick toothpicks (D) into the
Styrofoam balls to represent
sigma bonds between atoms, as
in the ethane molecule ^Hg)
represented here.
Use pairs of pipe cleaners (E)
cut to approximately 5 cm
lengths to represent pi bonds
between atoms, as in the ethene
(ethylene; C2H4) molecule
represented here.
Pi Bond
-196-
When triple bonds (one sigma
and two pi bonds) are to be
represented, dye the two pairs
of pipe cleaners different
colors for clarity. This
diagram represents a molecule
of ethyne (acetylene; C2H2) .
c. Notes
(i) If commercially manufactured Styrofoam or foam polystyrene balls are easily
available, they may be substituted for the hand-made balls described here.
(ii) The scale of approximate sizes of the balls used in these models is based
on the atomic radii for stable compounds listed in the Periodic Table of the
elements, for example:
Atomic Radius
Approximate
Element
in Angstroms
Ratio
C
0.77
2
N
0.75
2
0.73
2
H
0.32
1
(iii) If Styrofoam or foam polystyrene is not available, modeling clay (plasticine)
may be used for the balls and painted appropriate colors. However, once the clay
balls are painted, repeated puncturing of them with toothpicks will disfigure them.
Thus, it is recommended that they be used only to make permanent demonstration
models .
(iv) Pipe cleaners or match sticks may be substituted for the toothpicks if
desired.
(v) A kit for teacher use should contain:
2 dozen balls representing Carbon
2 dozen
2 dozen
1 dozen
1 dozen
1 dozen
Hydrogen
Oxygen
Halogens
Nitrogen
Sulfur
several dozen each straight and flexible connectors,
This would provide sufficient materials for constructing demonstration models
in the classroom. The same guantities listed above would be adeguate for laboratory
use for from one to four students.
-197-
(vi) The use of molecular models in the study of chemistry can enhance thestudents'
understanding of and ability to predict the various properties and interactions of
elements and compounds. These ball and stick models illustrate, roughly, the
relative bond angles, sizes and positions of atoms within a molecule in a clear and
simple form. They are not, however, scale representations of bond lengths or atomic
molecular sizes and shapes. In order to demonstrate the mathematical relations of
electrons in a given molecule, it will be necessary to employ a different style
model, that which is described in the next section.
(vii) The color code * used in these models is as follows:
Hydrogen - white
Carbon - black
Oxygen - red
Nitrogen - blue
Sulfur - dark yellow
Flourine - light green
Chlorine - dark green
Bromine - orange
Iodine - brown
Phosphorous - violet
Silicon - light yellow
*From the Portland Project Committee, Teacher Guide, Chemistry of Living Matter,
Portland, Oregon: Portland Project Committee, (1971, p 1/.
-19E
SKELETAL MODELS
Bl. Molecular Model Units*
Assembled View
C^3>
cz>
1) Tubing
C^D
<o=>
(2) Valence Cluster
(3) Connector
Exploded View
*Adapted from George C. Brumlik, Edward J. Barrett, and Reuben L. Baumgarten,
"Framework Molecular Models, " Journal of Chemical Education , XLI (1964), pp 221-223.
-199-
a. Materials Required
Components
(1) Tubing
(3) Connector
b. Construction
(1) Tubing
2) Valence Cluster
Qu Items Required
Milk Straws (Paper or
Plastic) (A)
Tempera (Poster)
Paints (B)
Pipe Cleaners (C)
Pipe Cleaners (D)
Finishing Nails (E)
Soft Iron Wire (F)
Glue
Dimensions
0.4 cm diameter,
approximately 20 cm long
Black, white, red,
yellow, green, blue,
orange
Approximately . 1 cm
diameter, 1 . 5 cm long
Approximately 0.05 cm
diameter
Mix a small amount of liquid
or dissolved soap with the
tempera paints (B) to reduce
their surface tension. Using
this mixture, paint several
milk straws (A) according to
the atom they are to represent:
Carbon - black
Hydrogen - white
Oxygen - red
Nitrogen - blue
Sulfur - dark yellow
Bromine - orange
[Consult Note (ii) for
additional colors . ]
Cut the straws into various
lengths depending upon the
scale used and bond represented.
Bend a pipe cleaner (C) into the
shape desired, and glue the
joint in the middle. When the
glue has dried, adjust the
angles of the arms of the
connector to suitable angles.
Bend
-200-
Vertical
Arm
Horizontal
Arm
Make tetrahedral (4 arms) shapes
with the angles of the arms at
about 109' .
Make trigonal bipyramid (5 arms)
shapes. Arrange the angles
between the three horizontal
arms to 120'. Adjust the two
vertical arms at right angles
to the horizontal arms.
Vertical
Arm
Horizontal
Arm
Construct octahedrons (8-pointed),
Adjust the angles between the
four horizontal arms to 90'.
Arrange the two vertical arms
at right angles to the horizontal
arms,
(3) Connectors
9t222ZZZ2Z^
Pipe Cleaner
(C)
Nail (E)
Soft Wire (F)
c. Notes
Construct straight connectors
to represent bonds between atoms
by wrapping a pipe cleaner (C)
around a nail (E) . Vary the
length of pipe cleaner used
according to the tightness
desired.
To make angular connectors to
be used to complete various
structures, bend a pipe cleaner
(C) in half. Then wrap soft
wire (F) around the pipe cleaner
and bend the assembly to a 90'
angle .
(i) These units can be used to build models of almost any molecule, The valence
clusters represent atomic nucleii, the intersection of the arms representing the
center of the atom. The tetrahedral (4-armed) valence cluster depicts bond angles
-201-
of approximately 109°, for sp^ hybridized orbitals or atoms with eight electrons in
their valence shell. The five-armed valence cluster can depict sp^ hybridization,
with 120' bond angles, for atoms engaged in (pi) bonds, as well as d sp^
hybridization, with 90° and 120° bond angles for atoms with ten atoms in their
valence shell . The six-armed valence cluster can represent sp hybridization with
bond angles near 180°, or d sp hybridization for atoms with twelve electrons in
their valence shell. The straight connector depicts 6 (sigma) bonds between like
or unlike atoms .
Electrons, whether bonded or unshared, are represented by the straws, color
coded and cut to scale.
The straws in a completed molecular model represent covalent radii of
bonding atoms, and van der Waals radii in the non-bond direction.
(ii) Below are charts* to guide the coloring and cutting of straws to represent
covalent radii or van der Waals radii. Any convenient scale may be used to
simulate the Angstrom unit (A) measurements of these forces. For example, a scale
of 10 cm/A produces large models ideal for lecture demonstrations, while a scale
of 2 cm/A yields smaller models suitable for student use.
Length of
Length of
Straw in cm
Straw in cm
Color
Atomic Cbvalent
(Scale:
10 cm/A)
(Scale:
of
Bond
Radii (A)
2 cm/A)
Straw
C — single
0.77
7.7
1.5
C - double
0.67
6.7
1.3
black
C - triple
0.60
6.0
1.2
O - single
0.74
7.4
1.5
O - double
0.62
6.2
1.2
red
O - triple
0.55
5.5
1.1
N - single
0.74
7.4
1.5
N - double
0.62
6.2
1.2
blue
N - triple
D.55
5.5
» 1.1
*Adapted from the Portland Project Committee, Teacher Guide, Chemistry of Living
Matter, (Portland, Oregon: Portland Pro ject Committee, 1971), pp 8-18.
-202-
Bond
(single)
Atomic Covalent
Radii (A)
Length of
Straw in cm
(Scale :
10 cm/A)
Length of
Straw in cm
2 cm/A)
Color
of
Straw
H
0.30
3.0
0.6
white
F
0.64
6.4
1.3
light green
Si
1.17
11.7
2.3
light yellow
P
1.10
11.0
2.2
violet
S
1.04
10.4
2.1
dark yellow
CI
1.00
10.0
2.0
dark green
Br
1.14
11.4
2.3
orange
I
1 1.33
13.3
2.7
brown
Atom
Cl
Br
Van der Waals*
o
Radii (A)
1.2
1.40
1.35
1.85
1.80
1.95
2.15
1.5
1.9
Length of
Straw in cm
(Scale:
10 cm/A)
12.0
14.0
13.5
18.5
18.0
19.5
21.5
15.0
19.0
Length of
Straw in cm
(Scale: o
2 cm/A)
2.4
2.8
2.7
3.7
3.6
3.9
4.3
3.0
3.8
Color
of
Straw
white
red
light green
dark yellow
dark green
orange
brown
blue
violet
-203-
B2 . Single Bond Structures*
(1) Carbon-Carbon
(5) H 2 (Water)
(2) Carbon-Oxygen
(4) CH 4 (Methane)
*Adapted from the Portland Project Committee, Teacher Guide, Chemistry of Living
Matter, (Portland, Oregon: Portland Project Committee, 19/1) , pp 19-28.
-204-
a. Materials Required
Components
(1) Carbon-Carbon
(2) Carbon-Oxygen
(3) Carbon-Hydrogen
(4) CH 4 (Methane)
(5) H 2 (Water)
b. Construction
(1) Carbon-Carbon
0.77A
Qu
:
2
:
(2) Carbon-Oxygen
(E) 0.74A
Items Required
Straight Connector (A)
Black Straws (B)
Straight Connector (C)
Black Straw (D)
Red Straw (E)
Straight Connector (F)
Black Straw (G)
White Straw (H)
4-armed Valence Cluster (I)
Dimensions
X/Bl
1.5
cm
X/Bl
1.5
cm
1.5
cm
X/Bl
1.5
cm
3.0
cm
X/Bl
Carbon-Hydrogen Bonds (F,G,H) 4.5 cm
[see (3) above]
4-armed Valence Cluster (J) X/Bl
Red Straws (K) i 5 cm
Red Straws (L) 2.8 cm
White Straws (M) 3.0 cm
Straight Connectors (N) X/Bl
Straight Connector (A)
i r
0.77A (D)
To represent this single covalent
bond between like atoms, cut two
black straws (B) to a scale
representation of the single
bond covalent radius of carbon
(X/BI), Note (ii) . For example,
cut the straws to 1.5 cm for
a scale of 2 cm/A. Join these
two straws with a straight
connector (A) .
To construct this model of a
single covalent bond between
unlike atoms, cut one black
straw (D) to represent the
single bond covalent radius for
carbon (1.5 cm, for example)
and a red straw to represent
the single bond covalent radius
for oxygen (E) (1.5 cm) . Connect
-205-
(3) Carbon-Hydrogen
(G) 0.71k
. 0.3A 1.2A
\ 'I t
L
■L
Van der Waals
radius of H
Nucleus of H atom
Covalent radius of H
4 ) CH 4 (Methane)
these two straws with a straight
connector (C) .
Construct the carbon-hydrogen
bond to include a representation
of the van der Waals radius for
hydrogen. Cut one black straw
(G) to indicate the single bond
covalent radius for carbon. Cut
one white straw (H) to show the
covalent radius of H (0.6 cm)
plus the van der Waals radius of
H (2.4 cm) . Draw a line around
the white straw at the inter-
section of these two values to
indicate the position of the
hydrogen nuculeus, then join the
black and white straws with a
straight connector (F) .
Construct four carbon-hydrogen
bonds (F,G,H) as described
above. Join them all together
at the carbon end by sliding
each onto an arm of the four-
armed valence cluster (I) and
pushing all the straws together
so that the connectors do not
show.
Cut two red straws (L) to
represent the van der Waals
radius of (2.8 cm). These
will represent two unshared
electron pairs, Cut two red
straws (K) to indicate the
single bond covalent radius
of (1.5 cm) . Use a straight
connector (N) to join each of
these with a white straw (M)
representing the covalent and
-206-
van der Waals radii of H (3.0 cm) .
Connect the two red straws and
two - H bonds with a four-armed
connector (J) as illustrated.
c. Notes
(i) Single covalent bonds between like atoms, such as the carbon-carbon bond,
may also be represented by one
C
C
straw, appropriately colored,
cut to twice the covalent radius.
Thus, the carbon-carbon bond
would be represented by one black straw, 3 cm long.
(ii) Unlike thespace-f illing models of X/Al, these models do not show molecular
shape. The shape of the constituent atoms within a molecule must be imagined;
the scale and orientation of the parts of the model show bond lengths, bond angles,
and bond thicknesses in reasonably accurate scale.
(iii) These skeletal molecular models are based on atomic orbital geometry, which
deals with the behavior of electrons in paths, or orbitals, in the space around
the nucleus of an atom. For a complete discussion of electrons, nucleii, and
orbitals, consult recent chemistry texts, such as Chemical Bond Approach Project,
Chemical Systems, (Webster Division McGraw-Hill Book Company, 1964), Chapter 10.
-207-
B3 . Double Bond Structures*
1) H 2 C = CH 2
Ethene)
(2) H
2 C =0
Formaldehyde)
Adapted from the Portland Project Committee, Teacher Guide, Chemistry of Living
Matter, (Portland, Oregon: Portland Project Committee, i9/l) pp 28-36.
-208-
(3) C 6 H 6
Benzene)
d
D
(4) H 2 C = C = CH2
(Allene)
-209-
a. Materials Required
Components
Qu
Items Required
Dimens:
(1) H 2 C=CH 2
2
5-armed Valence
CI
usters
(A)
X/Bl
(Ethene)
4
3
4
C-H Bonds (B)
Black Straws (C)
Black Straws (D)
4.5 cm
2.6 cm
3 . cm
4
Angular Connectors
(E)
X/Bl
(2) H 2 C=0
2
5-armed Valence
CI
usters
(F)
X/Bl
(Formaldehyde)
4
Angular Connectors
(G)
X/Bl
2
C-H Bonds (H)
4.5 cm
3
Red Straws (I)
1.2 cm
3
Black Straws (J)
1.3 cm
2
Red Straws (K)
3 . cm
2
Black Straws (L)
3 . cm
2
Red Straws (M)
1 . 5 cm
3
Straight Connectors
; (N)
X/Bl
(3) Ccflc 18 5-armed Valence Clusters (0) X/Bl
(Benzene)
6 C-H Bonds (P) 4.5 cm
18 Black Straws (Q) 2.6 cm
12 Black Straws (R) 3.0 cm
(4) H 2 C=C=CH 2 2 5-armed Valence Clusters (S) X/Bl
(Allene)
1 6-armed Valence Clusters (T) X/Bl
4 C-H Bonds (U) 4.5 cm
6 Black Straws (V) 2.6 cm
8 Black Straws (W) 3.0 cm
8 Angular Connectors (X) X/Bl
b. Construction
(1) H 2 C=CH 2 (Ethene) First construct four C-H
bonds (B) (X/B2) . Then complete
the H 2 C=CH 2 molecule as shown.
Use three 2 . 6 cm black straws
(C) to represent double bond
formation between like atoms.
The central black straw (C)
-210-
represents the a bond. The
two outside sections of black
straws (C) represent the two
arms of the bond, the
thickness of which is shown
by the four 3.0 cm black
straws (D) . Their length
represents the single bond
covalent radius of carbon.
(2) H 2 C=0 (Formaldehyde)
(I I —I
^_
(I) (N) (J)
Construct this model showing
double bond formation between
like atoms. First, construct
three C=0 bonds representing
the double bond radii C (J)
and (I), as shown. Make two
C-H bonds (H) (X/B2) .
Use the 5-armed valence clusters
(F) and angular connectors (G)
to join the straws. Indicate
the thickness of the it bond by
red straws on the oxygen side,
black straws on the carbon side.
-211-
(3) C fi H fi (Benzene)
^jfe,H>
(0) Modified
One corner, exploded view
(4) H 2 C=CH 2 (Allene)
Cut off and discard one
horizontal and one vertical arm
from each of twelve 5-armed
valence clusters (0) to form
3-cornered clusters .
Make six C-H bonds (X/B2) (P) .
Construct the three layered
model as shown. Use the
twelve 3 . cm black straws (R)
to represent the thickness of
the bonds (twice the single
covalent radius of carbon) .
Use the eighteen 2 . 6 cm black
straws (Q) to represent the
bond lengths (twice the double
covalent bond radius of carbon) .
The shared-bond aspect of the
ring structure often pictured:
is represented in the model by
the three-layered structure.
Construct four C-H bonds (U) .
Use one 6-armed valence cluster
(T) , as well as two 5-armed
clusters (S), to connect the
the components of the
H2C-C-CH a (allene) molecule.
-212-
Place the 6-armed cluster (T)
as shown to indicate that the
middle carbon atom is bonded
to each of the side carbons.
c.
Notes
(i) These four examples of double bond models illustrate some of the complex
double bond forms that can be built. By applying the principles thus illustrated,
it should be possible to construct almost any simple or complex double bonded
molecule.
(ii) because the forces holding two nucleii together in a double bond are greater
than those in a single bond, the nucleii are closer together, Thus, the straws
representing the C=C or C=R covalent distance are shorter than those representing
the C-C or C-R distance.
(iii) In the ^0=0 (formaldehyde) molecule, the slightly longer tubing representing
the bond thickness at the carbon atom than at the oxygen atom indicates a certain
strain on the double bond. The covalent radius of oxygen is used to model the
unbonded electrons, rather than the van der Waals radius as in the model of water,
because the C=0 bond "pulls" or distorts the oxygen electron cloud. C=N bonds
may be constructed just as C=C and C=0 bonds; blue tubing represents N.
-213-
B4 . Triple Bond Structure*
( 1) HC = CH
(Acetylene)
a. Materials Required
Components
(1) HC=CH
(Acetylene)
Qu
2
Items Required
Dimensions
6-armed Valence Clusters (A) X/Bl
Angular Connectors (B) X/Bl
C-H Bonds (C) 4.5 cm
Black Straws (D) 2.4 cm
Black Straws (E) 3.0 cm
*Adapted from the Portland Project Committee, Teacher Guide, Chemistry of Living
Matter, (Portland, Oregon: Portland Project Committee, 1971), pp 36-3/.
-214-
b. Construction
(1) HC=CH (Acetylene)
First make two C-H bonds (C)
(X/B2): Then use two 6-armed
valence clusters (A) and eight
angular connectors (B) to
connect the parts of the HC=CH
(acetylene) molecule as shown.
The 2 . 4 cm black straws (D)
indicate the length of the
triple bond, and are cut to
represent twice the triple
covalent bond radius for carbon.
Bond thickness is indicated by
the 3 . cm straws (E) or twice
the single bond radius for
carbon .
c.Notes
(i) Because the forces holding two nucleii together in a triple bond are
stronger even than those of a double bond, the nucleii are closer together. Thus,
the straws representing the C=R covalent distance are shorter than those representing
the C=R distances . Nucleii involved in sp hybridization with triple bond formation
are represented in the model by the 6-armed sp valence cluster.
(ii) In the HC=H (acetylene) model, the central carbon-carbon bond represents
the 6 bond. The four outside sections of black straws represent two double-armed
bonds .
-215-
35. Geometric Structures
(1) Straws
a. Materials Required
Components
(1) Straws
g u Items Required
Paper or Plastic
Milk Straws (A)
Pipe Cleaners (B)
b. Construction
(1) Straws
Dimensions
Approximately
. 4 cm diameter
Approximately
3 cm lonq
Cut the straws (A) to any
convenient length, 5 cm, for
example. Paint the straws,
if desired, with poster (tempera)
paints to which a small amount
of dissolved soap has been added.
*Adapted from D.C. Hobson and C. V. Platts, "Milk-Straw Molecular Models,
School Science Review, CLXIH ( 1 9 6 6 ) pp 694-701 .
-216-
(2) Connectors
1
Bend the cut pipe cleaners (B)
to form right angles.
Insert the pipe cleaners (B)
into the straws (A) , as shown,
to form secure connections.
C. Notes
(i) By selecting appropriate numbers of straws and connectors, a variety of
geometric forms may be built.
-217-
C. CRYSTAL STRUCTURE MODELS
CI. Crystalline Packing Models*
(1) Body-Centered
-Cubic Unit Cell
(2) Face-Centered
Cubic Unit Cell
(3) Closely-Packed
Hexagonal Unit Cell
* Adapted from J. W. Coakham, W. Evans, and H. Nugent,
School Science Review, CLXXIV (1969), pp 61-71.
'Introducing Crystal Structures,
-218-
a. Materials Required
Components
(1) Body-Centered
Cubic Unit Cell
Qu
(2) Face-Centered 14
Cubic Unit Cell
(3) Closely-Packed 17
Hexagonal Unit
Cell
b. Construction
Items Required
Styrofoam or Foam
Polystyrene Spheres
Styrofoam or Foam
Polystyrene Spheres
Styrofoam or Foam
Polystyrene Spheres
(1) Body-Centered Cubic Unit Cell
(A)
(O
Dimensions
Approximately 4 cm
diameter
Approximately 4 cm
diameter
Approximately 4 cm
diameter
Make the spheres (A) from
Styrofoam or foam polystyrene
(X/Bl) or purchase spheres
from a commercial source. Use
the nine spheres to represent
the atoms of the crystal
according to the "exploded"
diagram. Place four spheres
in the top and bottom layers,
and one in the middle. Use
toothpicks, pipe cleaners,
match sticks, or cement to
hold the spheres together,
(2) Face-Centered Cubic Unit Cell
Use this exploded diagram as
a guide for building the
face-centered cubic unit cell
from 14 spheres (B) . Place
five spheres in both top and
bottom layers, and four spheres
in the middle layer.
-2 19-
(3) Closely-Packed Hexagonal Unit Cell
Use seventeen spheres (C) as
illustrated to build the
closely-packed hexagonal unit
cell. Place seven spheres in
the top and bottom layers, with
three in the middle layer.
c. Notes
(i) The models described demonstrate three-dimensional patterns found in
crystals of metals, where the atoms are all of one size and the bonding forces
are egual in all directions. As with previous models, the use of molecular models
aids the student in both understanding the structure and predicting the character-
istics of the substances studied.
(ii) If it is necessary to construct crystal models showing different ion sizes,
smaller or larger Styrofoam spheres may be used. For example, ionic crystal models
may be constructed using
spheres 2 cm in diameter for
anions, and . 2 cm diameter
O for cations,
Anion
2 cm
Cation
0.2 cm
(iii) These models may be also used to demonstrate such aspects of crystal
structures as coordination number, most closely-packed planes and Miller Indeces,
(iv) For further discussions on the application of these models to the study
of the molecular structure of crystals, consult J, W. Coakham, W. Evans, and
H. Nugent, "Some Aspects of Crystal Structure, Part I," S chool Science Review,
CLXXIX, pp 339-350.
-2 2 0-
D. KINETIC-MOLECULAR MODEL
Dl. Kinetic Theory Model*
CO
(1) Tray
(2) Dowel
-(3) Marbles
a, Materials Required
Components
(1) Tray
(2) Dowel
(3) Marbles
b. Construction
(1) Tray
(2) Dowel
(3) Marbles
Qu Items Required
1 Wood (A)
2 Wood (B)
2 Wood (C)
1
Wooden Dowel (D)
250 Marbles or Glass Beads (E)
5 Marbles or Glass Beads (F)
Dimensions
1 cm x 30 cm x 30 cm
2 cm x 2 cm x 26 cm
2cmx2cmx30cm
Approximately 1.5
x 40 cm
Approximately 1 . 0-1 . 5
cm diameter
Larger than the others
Nail or glue the four wood
strips (B and C) to the flat
wood square (A) to form a
tray. Varnish the tray inside
and out to provide a slick
inside and outside surface.
Select a dowel (D) to support
one end of the tray.
Place the marbles or plastic
or glass beads (E) in the tray.
Use all of them to represent
the molecules in a solid or
liquid. Use only 40 - 50,
* Adapted from I. D. Taylor, "Kinetic Theory Nodels," School Science Review,
CLXIII(1963), pp 780-783.
-221-
plus the few larger marbles (F) ,
to represent the molecules in
a gas.
c . Notes
(i) To demonstrate, two-dimensionally, the kinetic activity of molecules in
matter, place all the marbles in the tray. Rest one end of the tray on the dowel
so that the marbles all roll
to the opposite end, packing
into a regular structure
with each marble, or "molecule"
touching six neighbors.
(ii) When the tray is at rest, none of the "molecules" move, representing the
theoretical condition of matter at absolute zero. when the tray is gently agitated
back and forth, the "molecules" begin to vibrate and to show "thermal expansion".
They occupy a larger volume, but generally retain the same relative position.
Occasionally a few molecules jump clear of the surface, representing the slight
vapor pressure of a solid.
(iii) As the tray is agitated still harder, with greater amplitude, the "solid"
"melts" with the "increase in temperature" (increase in kinetic energy). The
molecules slip out of place,
the volume increases, and
more molecules jump away from
the surface.
By slowing down the rate and amplitude of vibration, the "liquid" can be
converted back to a "solid". Slowing the vibration gently represents gradual
cooling and results in a regular structure. If however, the vibration suddenly
ceases, rapid cooling is demonstrated. The resulting "solid" shows an irregular
structure with many imperfections.
(iv) For a demonstration of a "gas", most of the molecules are removed, and
the tray is agitated more rapidly than for the "solid" or "liquid". All the
-222-
molecules move rapidly and
randomly about, traveling large
distances before colliding
with one another. A few larger
marbles, added to the "gas", move
with small, irregular, jerky
motions, representing the
Brownian motion of dust or
smoke particles in air.
(v) If a clean glass tray and overhead projector is available, the model may be
projected on a screen for a large class to see. The "molecules" show on the
screen as shadows.
-223-
XI. CHROMATOGRAPHIC APPARATUS
Chromatography, a powerful analytical technique of recent development, may be
performed with relatively simple apparatus. It is based upon the differential migra
tion of solutes in a liquid or solid medium and maybe used for both qualitative and
quantitative analysis of solutions.
A. QUALITATIVE CHROMATOGRAPHIC APPARATUS
This section includes chranatographic devices employing paper as the stationary
medium and briefly describes a few techniques for using these devices to identify the
components of a mixture.
B. QUANTITATIVE CHROMATOGRAPHIC EQUIPMENT
This section describes a device that allows for the separation of the components
of a mixture as well as the recovery of individual components for further experimenta-
tion or purification.
-224-
A. QUALITATIVE CHROMATOGRAPHIC APPARATUS
Al . Horizontal Paper Chromatography Device
(1) Paper
(2) Support
a. Materials Required
Components
(1) Paper'
(2) Support
b. Construction
(1) Paper
(2) Support
Qu I tems Required
1 Filter Paper (A)
1 Petri Dish (B)
Dimensions
Approximately 10 cm
diameter or larger
Slightly smaller
than filter paper
Use a circle or square of
filter paper (A) as the medium
for the chromatogram.
Select a petri dish or other
shallow container (B) just
slightly smaller than the
paper (A) on the support (B) .
C.Notes
(i) This apparatus can be set up almost instantaneously for rapid, qualitative
work. A drop of a colored solution to be analyzed is placed in the center of the
paper. Then, successive, small drops of the eluting solvent are dropped on top
of the original drop. The
solution spreads radially, and
as separation of components
occurs, concentric rings of
color will appear on the paper.
-225-
(ii) As an example of a test solution, a drop of black or blue-black, washable
ink may be used. The eluting solvent in this case could be water, methanol
(methylated spirits) or 70% ethanol.
(iii) Chromatography paper, white paper towels, blotting paper, newsprint paper,
or other white or light-colored, coarse-grained paper may be substituted for the
filter paper (A) .
-226-
A2 . Horizontal Paper Chromatography Device
(1) Paper
(2) Support
-^ (3) Cover
a. Materials Required
Components
(1) Paper
(2) Support
(3) Cover
b. Construction
(1) Paper
q u Items Required
1 Filter Paper (A)
1 Cup or Jar (B)
1 Glass Jar or Bowl (C)
Dimensions
Approximately 10 cm
diameter or larger
Slightly smaller than
filter paper
To cover paper and
support
Take a circle or square of
filter paper (A) or suitable
substitute and cut a tongue
across the paper to within
about 1 cm of the center of the
*Adapted from A. V. Jones, "Chromatography for Junior Schools," School Science
Review, CLXXIX: (1970), 298-300.
-227-
paper. Bend the tongue down at
a right angle to the paper (A) .
(2) Support Select a small cup or jar (B)
just slightly smaller than the
paper (A) . Rest the paper (A)
on the jar (B) with the paper
tongue extended into the jar.
(3) Cover Select a large glass jar or
bowl (C) to cover the support
and paper. Invert the cover to
enclose the other two compo-
nents .
c. Notes
(i) This apparatus, while only slightly more complex than that in the previous
section, has the added advantage that, once set up, it may be left to stand for
some time. A spot of test solution (e.g., ink or a concentrated extract made from
plant flowers, leaves , stems, or roots) is placed at the center of the paper (A) .
Then the small jar (B) is filled to within about 2 cm of the top with solvent (e.g.,
water or alcohol) . When the paper tongue is placed in the solvent, the liquid
will soak up the tongue to the test spot, and beyond. The components of the test
solution separate out, in rings, as the solvent progressively soaks the paper.
Covering the apparatus with a bowl or jar (C) helps prevent evaporation of the
solvent before it has had time to soak the paper.
(ii) The experiment continues until the solvent front reaches to within about
1 cm of the edge of the paper, or until it is apparent that it has stopped moving.
The paper is then removed from the apparatus and rapidly dried, using the drying
lamp (IX/A3), a fan, or other source of dry heat or moving air.
-228-
A3 . Horizontal Paper Chromatography Device *
(1) Paper
(2) Support
<3) cc
a. Materials Required
Components
(1) Paper
(2) Support
(3) Cover
Qu I tems Required
1 Filter Paper (A)
1 String (B)
1 Cup or Jar (C)
Glass Bowl or Jar (D)
Dimensions
Approximately 10 cm
diameter or larger
Approximately . 2 cm
diameter, 5-10 cm
long
Slightly smaller than
filter paper (A)
To cover paper (A) and
support (C)
-2 2 9-
b. Construction
(1) Paper
Cut Out
Slits
Take a circle or square of
filter paper (A) or suitable
substitute and cut several slits
radiating from the center as
shown. Punch a small hole in
the center and secure a piece of
string (B) with a knot, to act
as a wick.
(2) Support
(3) Cover
Select a small cup or jar (C)
just slightly smaller than the
paper (A) . Rest the paper (A)
on the rim of the jar (B) so
that the string wick (C) extends
into the jar.
Select a large glass jar or bowl
(D) to cover the support and
paper. Invert the cover to
enclose the other components.
c. Notes
(i) This apparatus is used in the same fashion as the preceding device. How-
ever, the slits in the paper
allow for more than one colored
spots of
Colored
Substances
substance or test solution to
be used simultaneously. The
spots are placed inside the "V"
of the slits, which prevent the
colors from merging.
-230-
A4 . Vertical Paper Chromatography Equipment
(1) Paper
(2) Solvent
Container
(3) Cover
a. Materials Required
Components
(1) Paper
(2) Solvent
Qu I tems Required
1 Chromatography
Paper (A)
1
Beaker, Bowl or Jar (C
Dimensions
Approximately 15 cm
x 15 cm
To contain paper (A)
when rolled into tube
(3) Cover
1 Glass Jar or Bowl (D)
To fit on or over
Solvent Container (C)
-231-
b. Construction
(1) Paper
With a pencil, draw a faint
line approximately 2 - 3 cm
from one edge of the paper (A) .
Use this line as a guide for
locating the spots of solution
or solutions to be tested. Make
the spots as small as possible
and about 2 cm apart .
Spots
•
Roll the paper (A) loosely into
a tube. Secure the edges
together with the paper clips
(B) such that the edges do not
touch or overlap.
(2) Solvent Container
(3) Cover
Set the rolled paper (A) into
the beaker, bowl, or jar (C)
and pour solvent into the
container (C) to a height of
about 1 cm.
Rest a large glass jar or bowl
(D) on or over the solvent con-
tainer (C) to prevent evapora-
tion of the solvent.
-232-
c. Note s
(i) If chromatography paper is not available, white paper toweling or blotting
paper may be substituted.
(ii) When this apparatus is in use, the solvent front migrates up the paper, (by
capillary action) resulting in the separation of the components of the test spot.
This is allowed to continue until it has reached to within several cm of the top
of the paper or until it is apparent that the solvent front will move no further
(when the rate of capillary action is in eguilibrium with the rate of evaporation) .
The paper is then removed from the apparatus and dried, and the final locations of
the color spots may be circled with pencil for easy identification.
(iii) This apparatus is also suitable for performing separation of colorless
substances, as long as the completed chromatogram can be treated in some way to
make visible the final location of the component of the substances. For example,
proteins, while generally colorless, may separate in this fashion. The dried
chromatogram is then sprayed with a ninhydrin solution, which reacts with the
amino acids in their final locations, making them visible as bluish spots or
smudges .
(iv) It is possible, with this apparatus, to submit a substance to chromoto-
graphic separation by two different solvents on the same sheet of paper. To run
such a two-dimensional chromato-
*
Direction
of First Run
-ip-
/ Separation
/ At' End of
X ■ Firs
:st Run
gram, a spot of the substance
is placed at the intersection
of two lines drawn on the
paper and treated as described
above, with one solvent. At
the end of the first run, the
chromatogram is removed from
the apparatus and dried.
spot of
Substance
-233-
Final Separation
Direction of
First Run
Direction
of Second
Run
Then the paper is rotated 90°
and again rolled into a tube,
with the first separation at
the bottom edge of the tube.
This tube is run a second time
with a second solvent. Thus,
it is possible to effect a
more complete separation than
is possible with one solvent
alone.
(v) A complete discussion of techniques and substances appropriate to chromato-
graphic separation is beyond the scope of this guidebook. For further information,
texts and resources on biochemistry, chemistry, and chromatography should be
consulted.
-234-
A5 . Vertical Strip Paper Chromatography Equipment
(1) Frame
(3) Cover
(2) Solvent
Container
a. Materials Required
Components
(1) Frame
(2) Solvent
(3) Cover
Qu I tems Required
2 Wood (A)
2 Wood (B)
4 Wood (C)
1 Wood or Masonite (D)
1 Thin, Stiff Wire (E)
1 Cup or Jar (F)
1 Plastic Bag (G)
Dimensions
1 cm x 1 cm x 8 cm
1 cm x 1 cm x 10 cm
1 cm x 1 cm x 20 cm
6 cm x 10 cm x 0.2 cm
Approximately 11 cm
long
Approximately 4 cm
high, to fit inside
frame
To fit loosely over
frame
-235-
b. Construction
(1) Frame
With nails and glue, secure the
frame parts (A), (B) , (C) , and
(D) as shown. Secure the wire
(E) to the frame, about 2 cm
from the top, with two small
nails .
(2) Solvent Container
(3) Cover
Select a shallow cup or jar
(F) that will fit inside the
frame. Ifnecessary, cut a
tall jar down to a height of
3 - 4 cm (I/F2) .
Select a plastic bag (G) that
will fit loosely over the
frame. It may be held in
place by clipping it with a
clothespin to a clamp or ring
that is supported about 10 cm
above the frame on the ring and
burette stand (IV/B5) or other
suitable support. Alternatively,
a frame to support the bag may
be constructed out of stiff
(e.g., coat hanger) wire.
-236-
c. Notes
(i) This frame may be used to support a strip of chromatography paper or
suitable substitute for either ascending or descending chromatographic operations.
For ascending operations, the
solvent container (F) remains
at the bottom of the frame. The
Paper strip, with one end just
touching the solvent, is hung
from the wire with a paperclip
The spot or spots of substance
to be separated is located at
the lower end of the strip,
just above the solvent. The
apparatus should be kept
covered by the plastic bag (G)
during the course of the experi-
ment to keep solvent evaporation
Spot -11 I ■ to a minimum.
'Solvent
(ii) In order to use the frame for descending operations, the solvent container
(F) is placed on the top shelf (D)
Solvent
The paper strip is then hung from the solvent
container, held in place with a
paper clip or clothespin, and
with a short piece folded over
to dip into the solvent. The
spot is located near the top of
the strip, outside the solvent
container. The solvent front
then moves down the paper in
the course of the experiment.
Spot
(iii) If a sufficiently large jar is available, it may be used as a cover in place
of the plastic bag (G) .
-237-
B. QUANTITATIVE CHROMATOGRAPHIC EQUIPMENT
Bl. Liquid-Column Apparatus
L
(1.) Col
umn
a. Materials Required
Components
(1) Column
q u Items Required
1 Glass Tube (A)
Cotton or Glass
Wool (B)
1-Hole Stopper (C)
Glass Tubing (D)
Dimensions
Approximately 1 . 5 cm
outside diameter,
25 cm long
To fit tube
Approximately . 5 cm
diameter, 5-10 cm long
Silica Gel (E)
28-200 mesh
-238-
b. Construction
(1) Column
(A)
Fire polish both ends of the
glass tube (A) to eliminate
sharp edges. Push a small wad
of cotton or glass wood (B)
about 1 cm into one end as a
plug.
Insert the small glass tube (D)
into the stopper (C) and push
the stopper into the large
glass tube (A) , and support the
column in a vertical position
in a burette clamp (IV/B5) or
other suitable support.
To pack the column with the
stationary medium, make a
slurry with several grams of
the silica gel (E) and water.
Pour this slurry into the top
of the column, and allow the
water to drain through the
small glass tube (D) , while the
moist silica gel is retained
by the plug (B) . If necessary,
pour additional slurry into the
column until about 15 cm of
the column is packed with
silica gel and about 1 cm of
water remains on top of the
silica gel. If desired, the
packing operation may be
hastened by applying slight
suction, by means of the
suction-filter flask (VI/A4)
coupled with a suction pump,
aspirator (V/A8) or other source
of suction.
-239-
c. Notes
(i) The flow of liquid through the column may be controlled, if desired, by the
addition of a stopcock, or flexible rubber tubing coupled with a pinch clamp
(IV/A4) or glass bead (III/B1) . A glass nozzle may also be added to the free end
of the flexible tubing.
(ii) To use this apparatus, the water remaining on the column is allowed to
drain until less than 1 cm remains to cover the silica gel. Then a small quantity
of a solution of colored material to be tested, in a concentrated form, is gently
pipetted on to the medium. The desired solvent is then added to the column, and
the column is allowed to drain slowly, using either gravity or very slight suction.
As the solvent moves down the column, carrying the substance with it,
separation will occur, as indicated by colored zones appearing on the medium. As
additional solvent is added to
■Solvent
Movementof
Colored "Zones
the column, the zones themselves
will migrate down the column;
if sufficient solvent is added,
each zone, consisting of a
specific component of the sub-
stance tested, may be washed
off the column and recovered
separately.
(iii) In addition to separating components of a substance and washing them down
the column with one solvent, it is possible to use additional solvents to wash
down a component or components that do not migrate at all with the first solvent.
To do this, allow the column to drain until less than 1 cm of the first solvent
remains on top of the medium, then add the second solvent to the column and proceed
with the washing as described above.
(iv) Other interesting results may be obtained by reversing the order of solvents
used, in successive runs, with the same test substance. For example, alcohol and
water are two solvents that may be used, in either order, to separate a mixture
of vegetable dyes or ink.
(\| One of the chief advantages of the liquid-column method of chromatographic
-240-
separation over paper chromatography is that the components of the substance
tested are recovered individually for use in further experiments or in quantita-
tive determinations. For example, a measured quantity of the test substance, in
a known concentration, is added to the column, and the solvent used and the
solutions recovered are measured. Then the components eluted are submitted to
volumetric or gravimetric quantitative analysis to determine the proportion of
each component present in the original sample.
(vi) Substances other than 28 - 200 mesh silica gel, and solvents other than
alcohol or water, may be used in liquid-column chromatography. Further experi-
mentation, as well as research into the technical literature on chromatography,
is suggested for the development of this technique. A useful reference for this
purpose is Erich Heftmann, Chromatography, Second Edition , (New York: Reinhold
Publishing Corporation, 1967) .
-241-
XII. MULTIPURPOSE SYRINGES
Many chemical techniques and experiments are readily performed using disposable
plastic syringes. Some of these uses will be described in this section, and the devices
have been grouped according to the concepts they illustrate. In addition to those
uses given here, syringes can also be used in column chromatography, ion exchange
devices, and other areas in chemistry.
A. TECHNICAL DEVICES
Two items of use in the chemistry laboratory are included here.
GAS STUDIES APPARATUS
Included here are several ways in which syringes may be used in studying the
production, collection, and properties of gases.
C. DIFFUSION APPARATUS
Diffusion of both gases and liquids can easily be studied with the aid of plastic
syringes .
D. OXIDATION APPARATUS
This section describes a number of devices used in the study of oxidation reactions.
E. ANALYTICAL APPARATUS
These devices are used in experiments to determine chemical formulae, structures,
and molecular weight .
F. CONDUCTANCE APPARATUS
The variation in conductivity of different solutions can be studied with the aid
of several devices which are fairly easily constructed with disposable syringes.
-242-
A. TECHNICAL DEVICES
Al . Dropper/Pipette
( U Syringe
a. Materials Required
Components
(1) Syringes
b. Construction
(1) Syringe
Qu I tems Required
1 Plastic Disposable
Syringe (A)
Dimensions
Capacity 10-50 ml
Select a calibrated, plastic
disposable syringe (A) with a
volume appropriate for the
desired use.
c . Notes
(i) In the smaller sizes, disposable syringes make excellent droppers with an
advantage being that the amount dispensed is measurable. Similarly, they can be
used for the same purposes for which pipettes are used. In the larger sizes,
syringes can substitute for burettes in titration experiments. Finally, syringes
may be utilized in calibrating improvised flasks, beakers, etc., of unknown
capacity.
(ii) Placing a medium-sized diameter needle (inside diameter approximately
0.03 cm) on the syringe nozzle will allow solutions to be carefully and accurately
delivered, drop by drop.
-243-
A2 . Pump
(2) Connecting Tubing
(1) Syringe
a. Materials Required
Components
(1) Syringe
(2) Connecting
Tube
b. Construction
(1) Syringe
(2) Connecting Tubing
q u Items Required
1 Plastic Disposable
Syringe (A)
Plastic or Rubber
Tubing (B)
Dimensions
Capacity approxi-
mately 2 ml
Approximately 10 cm
long, diameter to
fit syringe nozzle (A)
Take a plastic, disposable
syringe (A) with a volume appro-
priate for the desired use.
Attach a length of plastic or
rubber tubing (B) to the
syringe nozzle when the pump is
to be used in hard-to-reach
places.
c. Notes
(i) To use the pump, connect the tubing to the object from which gas or liquid
is to be removed. Withdraw the plunger to draw gas or liquid into the syringe.
Then remove the tubing from the object or container, direct the tubing into an
appropriate container or waste receptacle , and depress the plunger to expell the
gas or liquid through the tubing.
-244-
(ii) With two modifications,
the syringe may be used to provide continuous pump-
ing action without removing the
tubing from the object from
which substances are pumped.
Make a small hole in the base of
the syringe barrel with a drill
or hot wire, and add a pinch
clamp (IV/A4) to the tubing to
close it off. In use, the
tubing is connected to the
object from which gas or liguid
is to be removed. Then the
pinch clamp is removed from the
tubing and the hole in the
syringe barrel is covered with
a finger. The plunger is withdrawn to draw material into the syringe. To expell
the contents of the syringe through the hole, the tubing is closed with the pinch
clamp, the hole is uncovered, and the plunger is depressed.
Pinch Clamp
-245-
GAS STUDIES APPARATUS
Bl Gas Production and Collection Device *
" ^ — Bd B
\
(?) Connecting Tubing
(3) Reaction Chamber
V
(1) Syringe
t)
a. Materials Reguired
Components
(1) Syringe
(2) Connecting
Tube
(3) Reaction
Chamber
q u Items Reguired
Plastic Disposable
Syringe (A)
Rubber or Plastic
Tubing (B)
Glass Tubing (C)
Hard Glass Test Tube
or Flask (D)
1-Hole Stopper (E)
Dimensions
Capacity 10-50 ml
2 cm long, diameter
to fit syringe
nozzle (A)
Approximately . 5 cm
diameter, 10 cm long
Capacity 20-100 ml
To fit test tube or
flask (D)
b. Construction
(1) Syringe
(3) Connecting Tubing
Select a plastic, disposable
syringe (A) of appropriate
capacity.
Connect the short piece of
flexible rubber or plastic
tubing (B) to the syringe
nozzle .
Heat the glass tubing (C) suffi-
ciently to bend it to a slight
angle (about 30°) . Connect
*Adapted from Paul D. Merrick, Experiments with Plastic Syringes, (San Leandro,
California: Educational Science Consultants, 1968), p 19.
-246-
one end of the glass tubing to
the rubber or plastic tubing (B) .
(3) Reaction Chamber Seal a hard glass test tube or
flask (D) (capacity from 20 to
100 ml, depending on the desired
use) with a one-hole stopper (E) .
Use a rubber stopper if caustic
materials are to be used in the
apparatus. Insert the free end
of the glass tubing into the
hole in the stopper.
c. Notes
(i) This simple reaction apparatus, suitable for either lecture demonstration
or student laboratory use, may be employed in a number of ways. In the simplest
qualitative experiments, the use of the syringe allows liquids to be introduced
into the reaction chamber where they react with solids or other liquids. A
number of gases can be produced using this or similar devices. For example,
injecting a 3% solution of hydrogen peroxide from the syringe into a suspension of
dried yeast and water in the tefetube will yield oxygen gas. Also, injecting a
concentrated solution of baking soda from the syringe into vinegar will yield
carbon dioxide. Finally, injecting vinegar into water and a piece of magnesium
ribbon will cause hydrogen gas to be liberated. The gas liberated will collect in
the syringe, pushing the plunger out as more and more gas is given off. Turning
the plunger slightly will assure that the gas is at atmospheric pressure.
(ii) This apparatus may also be used for quantitative studies in the above
reactions. The solid reactants must be carefully weighed or measured, and the use
of the syringe allows very precise amounts of liquids to be introduced into the
reaction chamber. The volume of the gas evolved may be read from the syringe. The
change in volume of gas in the syringe may be plotted against time to give a
measure of the rate of reaction. In addition, the volume of gas liberated may also
be plotted as a function of temperature and/or the concentration of one or more of
the reactants used.
(iii) In a third type of experiment using this apparatus, solids which give off
gases when heated are placed in the test tube, and the gas is collected in the
syringe. Begin with the syringe plunger fully depressed, and as the gas is evolved,
it will push the plunger back, giving a quantitative measure of the amount of gas
produced. In using this device, clamps to hold both the test tube and syringe are
needed. As an example, red lead can be heated in the test tube, and the gas
-247-
evolved collected in the syringe. It should be noted, however, that this will
spoil the test tube. Instead, potassium permanganate can be used, and no spoilage
of the test tube will occur. However, some asbestos wool must be put in the upper
end of the test tube to prevent pieces of the potassium permanganate from entering
the syringe.
(iv) The experiments based on the use of this apparatus are adapted from
Nuf field O-Level Chemistry, Collected Experiments, (London: Longmans /Penguin
Books, 1967), pp 9, 229-231, 297-299.
(v) If a glass reaction chamber is not available or is not desired, a second
syringe, the same size as the
<€
v-
Holes
(- Slit
€
Collecting
Chamber
Connecting
Tubing
React ] on
Chamber
first but slightly modified,
may be substituted. First,
with a hand drill or hot nail
or wire, bore two holes, approx-
imately 0.3 cm in diameter,
opposite each other about half-
way along the length of the
barrel. With a drill and saw
or hot nail, make a slit in
the syringe plunger as shown.
Push the plunger into the
syringe, and lock it in place
by inserting a nail approxi-
mately 0.3 cm wide and 5 cm
long through the holes in the
barrel and slit in the plunger.
Place in the lower syringe a
small piece of material which
will react with the liquid to
be placed in the upper syringe.
Replace the plunger in the
lower syringe, insert the nail
stop, and depress the plunger
until the nail prevents further
movement. Draw a quantity of
liquid into the upper syringe,
and fasten the two together
with the short piece of tubing.
Next, inject all of the liquid
into the lower syringe and
-248-
leave the upper syringe plunger in the depressed position. As gas is given off in
the lower syringe, it will expand and push out the plunger of the upper syringe
until the upper syringe is filled with gas or the reaction stops. Solids and
liguids which can be used as outlined to produce gases include animal charcoal and
hydrogen peroxide (to form oxygen), metals and dilute acids, carbonates and acids.
(vi) The above modification is based on a design by Andrew Farmer, "The
Disposable Syringe — A Rival to the Test Tube?, " School Science Review, CLXXIV
(1969), 30-31.
■249-
B2 . Micro-Generator
(1) Syringe
(2) Beaker
a. Materials Required
Components
(1) Syringe
(2) Beaker
b. Construction
(1) Syringe
(2) Beaker
C .Notes
Qu
:
Items Required
Disposable Plastic
Syringe (A)
Glass Jar or Beaker (B)
Dimensions
Capacity 10-50 ml
To accommodate syringe
as shown
Select a plastic, disposable
syringe (A) of a size appro-
priate to the amount of gas
desired.
Select a glass jar or beaker
(B) such that the syringe can be
rested in it more or less
vertically.
(i) As an example of its use, the micro-generator can be employed to generate
hydrogen sulphide qas (H2S) . Simply place a small piece of ferrous sulphide in the
syringe, and put a small amount of dilute hydrochloric acid in the beaker. Draw
a portion of the acid up into the syringe until it touches the ferrous sulphide,
and leave the syringe resting in the beaker. The gas will collect in the syringe,
above the acid. If desired, the needle may be reattached to the syringe when it
comes time to bubble the gas through a test solution.
*Adapted from L. A. George, "Two Further Uses for Disposable Syringes," School Science
Review, CLXX (1968), 113.
■250-
B3 . Gas Solubility Device/Reaction Rate Chamber
(1) Syringe
(2) Plug
a. Materials Required
Components
(1) Syringe
(2) Plug
b . Construction
(1) Syringe
(2) Plug
q u Items Required
1 Plastic Disposable
Syringe (A)
Nail (B)
Dimensions
Capacity approxi-
mately 2 5 ml
To fit syringe
nozzle (A)
Take a plastic, disposable
syringe (A) of 25 ml or other
desired capacity.
Use the nail (B) to completely
seal the syringe after a
substance has been drawn into
it.
c. Notes
(i) A number of simple solubility experiments may be done with syringes that
can be sealed airtight. For example, the syringe may be half filled with cold
water, with the plunger just above the water level. Seal the nozzle, and when
the plunger is withdrawn further, air will be seen to bubble out of the water.
This same demonstration may be repeated with distilled water, or cold water through
which CO2, O2, N2, etc., have been bubbled. A slightly more sophisticated demon-
stration involves water through which has been bubbled for about five minutes.
When a small amount of bromothymol blue is added, the solution will be yellow.
Add this to a sealed syringe, and as the plunger is withdrawn, CO2 will bubble out
and the color of the solution will change to pale green. If the syringe is shaken,
-251-
the CO2 will be redissolved, and the solution will once again be yellow. The
experiment may be tried repeatedly.
(ii) A single syringe can also be used to illustrate the effect of pressure on
solubility. Attach a short length of rubber tubing to the nozzle, and also attach
a clamp or piece of wire to the rubber tube which can be used to close the tube.
Fill the syringe half full of water, and fill the remainder of the barrel with CO2 .
Shake the syringe vigorously, then hold the tube under water, release the clamp
(or loosen the wire), and note the rise in water level in the syringe. Repeat the
experiment, but depress the syringe plunger while shaking it. There will be a
noticeable difference in the rise of the water level.
(iii) The above experiments have been adapted from Andrew Farmer, "The Disposable
Syringe — A Rival to the Test Tube?," School Science Review , CLXXIV (1969), 35-37.
(iv) Another experiment that can be performed with the sealed syringe involves
the relationship between reaction rate and pressure. Fill the syringe partially
with vinegar and add sodium bicarbonate. Carbon dioxide will be given off, and
this reaction can be speeded up or slowed down and stopped by decreasing or
increasing the internal pressure with the plunger, respectively. This experiment
is based on Paul D. Merrick, Experiments with Plastic Syringes, (San Leandro,
California: Educational Science Consultants, 1968), p 6.
-252-
34. Charles' Law: Volume/Temperature Device
Q£>
(1) Sy
ringe
(2) Weight
a. Materials Required
Components
(1) Syringe
(2) Weight
b. Construction
(1) Syringe
Qu
:
Items Required
Plastic Disposable
Syringe (A)
Small Eyed Screw (B)
Lead Sinker or Weight (C)
Dimensions
Capacity 35 ml
To seal syringe
nozzle (B)
Approximately 30 g
Make two small holes in the
bottom of the syringe barrel
(A) with a hand drill or hot
wire.
Holes
* Adapted from Paul D. Merrick, Experiments with Plastic Syringes, (San Leandro,
California: Educational Science Consultants, 1968), p 32.
-253-
on
Screw a small, eyed screw (B)
into the syringe nozzle to seal
the nozzle and to provide an
attachment for the weight (C) .
(2) Weight
Hang a lead sinker (C) or other
suitably sized weight (approxi-
mately 30 g) from the eyed
screw.
c. Notes
(i) With the plunger set so that a 35 cc volume of air is trapped in the
syringe barrel, the device is put into a container of hot water. Water will be
seen to enter the syringe barrel as the expanding air leaves it through the small
holes (the effect will be more visible if a drop of vegetable dye is placed in
the nozzle depression before beginning) . Varying amounts of water will enter the
syringe depending upon the water temperature. Good quantitative data can be
gotten by comparing the water temperature with the amount of water entering the
syringe (or the air volume of the syringe after the water enters) . The device
should be removed from the water to return the air volume to its original reading
for each temperature/pressure reading.
-254-
C. DIFFUSION APPARATUS
CI. Liquid Diffusion Device
o
&£>
T
Jl) Syringe
a. Materials Required
Components
(1) Syringe
b. Construction
(1) Syringe
C .Notes
Qu I tems Required
1 Plastic Disposable
Syringe (A)
Dimensions
Capacity approxi-
mately 50 ml
Select a plastic, disposable
syringe (A) of a large capacity
(35 - 50 ml, for example) .
(i) To use this device to study diffusion of liquids, fill the syringe almost
completely with cold water. Then, draw a small amount of colored solution into it
and let the 'syringe stand. Diffusion should be complete after two or three days.
Colored solutions which work well include potassium permanganate and copper
sulphate.
(ii) This experiment has been adopted from Andrew Farmer, "The Disposable
Syringe: Additional Experiment, " School Science Review , CLXXVIII (1970), 60.
-255-
C2 . Gas Diffusion Device
(1) Gas
Container
OT
o
(2) Connecting
Tubing
3) Indicator
Container
Q'D
a. Materials Required
Components
(1) Gas Container
(2) Connecting
Tubing
(3) Indicator
Container
g u Items Required
1 Plastic Disposable
Syringe (A)
1 Rubber or Plastic
Tubing (B)
1 Pinch Clamp (C)
1 Plastic Disposable
Syringe (D)
Indicator Solution (E)
(Limewater or Litmus
Solution)
Dimensions
Capacity approxi-
mately 25 ml
Approximately 15 cm
long, diameter to
fit syringe nozzles
IV/A4
Capacity approxi-
mately 25 ml
Approximately 5 ml
*Adapted from Andrew Farmer, "The Disposable Syringe — A Rival to the Test Tube?, "
School Science Review, CLXXIV (1969), 35.
-256-
b. Construction
(1) Gas Container
(2) Connecting Tubing
(3) Indicator Container
Select a plastic, disposable
syringe (A) of about 25 ml
capacity.
Use a length of flexible
tubing (B) to connect the two
syringes together. Make a
pinch clamp (C) or use another
suitable clamp to close the
tubing.
Select a plastic, disposable
syringe (D) with the same capa-
city as that used for the gas
container. Fill it with the
indicator solution (E) .
C. Notes
(i) Place an indicator solution (e.g., limewater) in the indicator container.
A gas (e.g., CO2 ) is collected in the gas container syringe and the two syringes
are connected by the tubing. When the clamp is released, the gas will diffuse
until it reaches the indicator solution and causes a reaction (white precipitate
when CO2 meets limewater) . The time taken for the gas to diffuse may be measured.
(ii) A slight modification of the indicator container will allow a comparison
of gas diffusion rates in air
Holes ,
<°
t
\
0.".:
d
^- Hole
and in a partial vacuum. This
is done by making two holes
opposite each other near the
mouth of the syringe barrel
with a hand drill or heated
nail. Then one hole is made in
the plunger, as shown. The
holes should be made so that a
nail can be pushed through the
barrel and plunger.
-257-
Gas
To repeat the above experiment with a partial vacuum, the nail is removed
from the indicator syringe
and several ml of indicator
solution are drawn into the
syringe. Then the tubing,
closed by the clamp, is attached
to the syringe. With the clamp
in place the plunger is pulled
back, to create a partial
vacuum, and the nail is pushed
through the syringe barrel and
plunger to hold the plunger
in position. Gas is collected
in the other syringe and
allowed to diffuse to the
indicator solution, and the
time taken is compared to the
results of the first experiment.
-258
D. OXIDATION APPARATUS
Dl. Oxidation Indicator: Membrane Type *
(2) Membrane
(1) Syringe
Assembly
a. Materials Required
Components
(1) Syringe Assembly
(2) Membrane
b. Construction
(1) Syringe Assembly
<BQ
I
Cut
q u Items Required
1 Plastic Disposable
Syringe (A)
1 Nail (B)
Thin Sheet Rubber (C)
Rubber Band or Thin
Wire (D)
33
"TO
Holes
r
Hole
Dimensions
Capacity 25-50 ml
Approximately . 2 cm
diameter, 4 cm long
Approximately
5 c m x 5 c m
Take a medium to large capacity
(25 - 50 ml) plastic, disposable
syringe (A) . Cut off the end
of the barrel near the nozzle.
Then, with a hand drill or hot
nail, make two holes approxi-
mately 0.3 cm in diameter
opposite each other near the
mouth of the barrel.
In the same fashion, make one
hole in the stem of the plunger,
near the plug, as shown.
*Adapted from Paul D. Merrick, Experiments with Plastic Syringes, (San Leandro,
California: Educational Science Consultants, 1968), p 6.
-259-
Insert the plunger into the
syringe barrel, and push the
nail (B) through the holes in
the barrel and plunger to fix
the plunger in position.
(2) Membrane Cut a 5 cm x 5 cm square of
thin sheet rubber (C) (from a
toy balloon, for example) .
Stretch it over the open end of
the syringe barrel and secure
it in place with a rubber band
(D) or length of thin wire.
C. Notes
(i) This simple device will give a visual indication that oxidation is taking
place. For example, if wet steel wool or a piece of cotton soaked in alkaline
pyrogallol [Note (i) XII/D41 is inserted into the barrel of the syringe and the
plunger fixed in place with the nail , as the material reacts with the oxygen in
the air the pressure inside the syringe will gradually be lowered. This can be
seen since the rubber sheet will be pulled further and further into the syringe.
-260-
D2 . Oxidation Indicator: Displacement Type *
(1) Syringe
(2) Beaker
a. Materials Required
Components
(l)Syringe
(2) Beaker
b. Construction
(1) Syringe
(2) Beaker
Qu Items Required
1 Plastic Disposable
Syringe (A)
1 Jar or Beaker (B)
Dimensions
Capacity approximately
35 ml
To support syringe
Select a plastic, disposable
syringe (A) of medium to large
capacity (35 - 50 ml) . No
modifications are necessary.
Choose a small glass jar (B) ,
beaker, or other container
that will support the syringe,
as shown.
c_ Notes
(i) Place a portion of wet steel wool (it may have to be washed in vinegar
to remove the anti-rust coating) in the syringe barrel and position the plunger
*Adapted from Paul D. Merrick, Experiments with Plastic Syringes, (San Leandro,
California: Educational Science Consultants, 1968}, p 2.
-261-
so that some predetermined air volume is trapped in the syringe. Place the syringe
into a small amount of water in the beaker so that the nozzle is under water. As
the steel wool reacts with the oxygen in the air, pressure inside the syringe will
drop and water will be drawn up into the syringe barrel. Dyeing the water with
non-fast vegetable dye will make the visual display more evident.
Cotton wool or other absorbent material soaked with alkaline pyrogallol
[Note (i) XII/D4] may be substituted for the wet steel wool.
-262-
D3 . Oxidation Rate Indicator
(1) Indicator
a. Materials Required
Components
(1) Indicator
b. Construction
(1) Indicator
C. Notes
Qu I tems Required
1 Respirometer
Dimensions
BI0L/VIII/D1 (1)
Construct this item according
to directions given for the
Respirometer, biol/viii/di(1)
(i) Begin operation of this device by fastening the plastic tubing to the
reservoir and to the nozzles of the syringes. Fill the reservoir with water which
has been colored with non-fast vegetable dye. Items which react with oxygen in
the air, including wet steel wool, white phosphorus, or alkaline pyrogallol (soaked
cotton wool) , are placed in the barrel of one syringe, where they react, removing
oxygen from the trapped air. This results in a lowering of pressure which causes
the colored water to be drawn from the reservoir into the clear tubing. The
second syringe serves as a control, containing only air. The rate of the reaction
can be judged from the speed with which the water column moves toward the syringe.
* Adapted from Paul D. Merrick Experiments with Plastic Syringes, (San Leandro,
California: Educational Science Consultants, 1968), p 11.
-263-
D4 . Stoichiometry Device *
1) Syringe
(2) Connecting Tubing
(3) Glass Tube
(4) Water Container
a. Materials Required
Components
(1) Syringe
(2) Connecting Tube
(3) Glass Tube
Qu
(4) Water Container
Items Required
Plastic Disposable
Syringe (A)
Rubber or Plastic
Tubing (B)
Glass Tubing (C)
Glass Tubing (D)
1-Hole Stopper (E)
Cotton (Cotton Wool) (F)
Pan or Tray (G)
Dimensions
Capacity 10 ml
or more
To fit syringe
0.5 cm diameter,
2 cm long
2-3 cm diameter,
10 cm long
To fit large tubing
Capacity approximately
1 liter
*From Paul D. Merrick, Experiments with Plastic Syringes, (San Leandro, California:
Educational Science Consultants, 1968), p 19.
-264-
b. Construction
(1) Syringe Select as many plastic,
disposable syringes (A) of
the same capacity (approximately
10 ml) as desired.
(2) Connecting Tubing Connect the short rubber or
plastic tubing (B) to the
syringe nozzle. Connect the
free end of the rubber or
plastic tube to the short piece
of glass tubing (cj .
(3) Glass Tubing Seal one end of a large diameter
glass tube (D) with a one-hole
stopper (E) and insert the
glass tube (C) into the hole
in the stopper.
Push a small wad of cotton (F)
(cotton wool) into position
near the top of the glass tube,
below the stopper.
(4) Water Container For the water container, use a
pan, tray, jar, or beaker (G)
into which the desired number
of syringe assemblies can be
filled.
c. Notes
(i) An alkaline pyrogallol solution must be prepared for use with this apparatus.
Put 10 g powdered pyrogallol [1, 2, 3 — trihydroxybenzene, Cgf^fOH^] and 2 g
sodium hydroxide (NaOH) pellets into a small flask or test tube. Add about 30 ml
HoO. Tightly cap the container and shake it until all the solid dissolves.
Avoid stirring the container to introduce air, as the alkaline solution will
rapidly absorb oxygen and become useless for the experiment.
(ii) For experimentation in stoichiometry, several of these syringe assemblies
need to be set up. Each should have an identical amount of the pyrogallol
solution (or other reducing agent) in the syringe. Place all the devices open
-265-
end down in the water container. Inject varying amounts of the pyrogallol (for
example, 0.5, 1, 1.5 . . . 10 ml) into the glass tube where it will be absorbed in
the cotton. The pyrogallol will then react with the oxygen in the air in the
tube, and continue to react until either the pyrogallol or oxygen is consumed.
As oxygen is removed from the air, pressure in the tube will fall, and water
will be drawn up into it from the trough. The height of the water in the tube
then becomes a measure of the amount of oxygen consumed, and will be seen to be
proportional to the amount of pyrogallol used, until the upper limit is reached.
on
(iii) If glass tubes are not available, syringe barrels may be substituted.
A short piece of plastic or
rubber tubing is used to
connect the upper syringe
Upper an d lower syringe barrel,
Syringe
which is used in an inverted
position.
X
Lower
Syringe--
Sarrel Only
-266-
E. ANALYTICAL APPARATUS
El. Air Composition Device *
Q
(1) Syringe and
Tubing
(2) Water
Container
a. Materials Required
Components on
Items Required
(i) Syringe a nd 2
Tubing
Stoichiometry Device (A)
(2) Water Container 1
Pan or Tray (B)
—
Limewater (C)
2
Modeling Clay (D)
(Plasticine)
2
Candles (E)
Dimensions
XII/D4, Components
(1), (2), and (3)
Approximately 1 liter
Small wads
Approximately . 5 cm
diameter, 5 cm long
*From Paul D. Merrick, E xperiments with Plastic Syringes, (San Leandro, California:
Educational Science Consultants, 1968), p 20.
-267-
b. Construction
(1) Syringe and Tubing
(2) Water Container
h
Prepare two syringe and tubing
(A) assemblies, as described for
the Stoichiometry Device
(XII/D4) .
Support each candle (E) in a
small wad of modeling clay (D) ,
about 5 - 10 cm apart on the
bottom of the pan or tray (B) .
The clay wad must be smaller
than the diameter of the glass
tube used.
&
Pour sufficient limewater (C)
into the pan or tray to cover
the wad of clay and 1 cm or so
of the candles.
c. Notes
(i) To investigate the proportion of oxygen in the air, an alkaline pyrogallol
solution, prepared according to instructions inXII/D4, is required. Each syringe
should contain an equal amount of the pyrogallol solution (5 ml, for example) .
(ii) When the syringe assemblies, with alkaline pyrogallol solution in each
syringe, and the candles in the limewater have been prepared, light one candle.
After a few seconds, place one of the syringe assemblies over each candle. Allow
them to stand for about five minutes after the burning candle goes out to allow
the limewater to remove CO2 from the air in its tube. At this time, limewater
will have risen into the tube to compensate for the lostCC^. Mark this level of
limewater with a wax pencil or felt-tipped marker.
Using a syringe pump (see XII/A2), remove air from the other tube until the
limewater rises to the same level in the second tube as it had in the first. Mark
this level, also. Now, inject alkaline pyrogallol from the syringes onto the
cotton wads. This will react with the oxygen in the air, and remove all of it if
enough pyrogallol is used. The water level in each tube will have risen. The
amount of rise in the first tube (the one containing the candle) will be compared
to the amount of rise in the second tube. Also, the change in trapped air volume
in both tubes should be noticed. By doing this, it will be found from the first
tube that the burning candle removes only about 25% of the oxygen in the air, while
the change in volume in the second tube will show that air is about 21% oxygen.
-26E
E2 . Gas Reaction Chamber
u
(1) Syringe
«dfesilH
(4) Clamp
(2) "T" Tube
e=o
„(3) Tubinc
a. Materials Required
Components
(1) Syringe
(2) "T" Tube
(3) Tubing
(4) Clamp
b. Construction
(1) Syringe
(2) "T" Tube
Qu I tems Required
2 Plastic Disposable
Syringe (A)
:
Glass "T" Tube
3 Rubber Tubing (C)
Pinch Clamp (D)
Dimensions
Capacity 50 ml
Approximately 0.5
dm diameter
To fit syringe nozzle,
approximately 8 cm
long
IV/A4
Select two 50 ml plastic,
disposable syringes (A) . Secure
the syringes in a horizontal
position by appropriate supports.
Use a glass or metal "T" tube
(B) with three outlets. If
available, a three-way valve
(stopcock) may be substituted
for the clamps and "T" tube.
* Adapted from Nuffield O-Level Chemistry . Collected Experimen ts, (London : Longmans/
Penguin Books, 1967), p 237.
-269-
(3) Tubing
<cz
\i
x>
(4) Clamp
Connect the two syringes to
the "T" tube with two short
pieces of rubber tubing (C) .
Use a third piece of tubing (C)
to connect the apparatus to a
source of gas.
Use three pinch clamps (0)or
other suitable clamps to close
each section of tubing.
c. Notes
(i) To determine the number of gram-molecules of hydrogen chloride that react
with one gram-molecule of ammonia, set up the apparatus as shown in the main
illustration. Using the correct combination of open and closed clamps, fill one
syringe with dry amnonia gas, empty it, and repeat one or two more times to "flush"
the syringe. Follow the same procedure with the other syringe using dry hydrogen
chloride. Then, fill the first syringe with 40 cc of the dry ammonia and fill the
second with 50 cc of the dry hydrogen chloride. With the two syringes open to
each other but closed to the atmosphere , inject the hydrogen chloride into the
syringe of ammonia. The two gases will react, forming ammonium chloride. That
about 10 cc of hydrogen chloride remains unreacted is shown by passing the gas over
damp indicator paper. Thus, 40 cc of amnonia reacts with 40 cc of hydrogen
chloride.
-270-
F. CONDUCTANCE APPARATUS
Fl. Conductance Device
(1) Injecting
Syri nge
(2) Receiving
Syringe
a. Materials Required
Components
Qu
Items Required
(1) Injecti
Syringe
ng
1
Plastic Disposable
Syringe (A)
(2) Receivi
Syringe
ng
1
Plastic Disposable
Syringe (B)
(3) Wire
2
Insulated Wire (C
(4) Tubing
1
Plastic or Rubber
Tubing (D)
Dimensions
Capacity approxi-
mately 35 ml
Capacity approxi-
mately 35 ml
Approximately . 3 cm
diameter, 50 cm long
To fit syringe
nozzles, 2 cm long
b. Construction
(1) Injecting Syringe
Use a 35 ml plastic, disposable
syringe (A) , with no modifica-
tions, for this component.
*Adapted from Andrew Farmer, "The Disposable Syringe — A Rival to the Test Tube?,
School Science Review, CLXXIV (1969) , 32-34,
-271-
(2) Receiving Syringe
C
v^
Hole
Take a 35 ml plastic, disposable
syringe (B) and with a hand drill
or hot wire make two holes,
approximately 0.2 cm in diameter,
opposite each other near the
base of the barrel.
(3) Wire
Epoxy Glue
Seal
Remove about 1.0 cm of insula-
tion from each end of both
wires (C) . Insert one bare end
of each wire through the holes
in the syringe barrel (B) . Seal
the holes with epoxy glue, taking
care to see that no epoxy covers
the bare wire inside the syringe
barrel .
(4) Tubing
c .Notes
Connect the two syringes to-
gether with a short piece of
plastic or rubber tubing (D) .
(i) This apparatus may be used to investigate the variation of conductance as two
solutions are mixed. The wires
are connected in series to a
1.5 volt cell and an ammeter as
shown. One liquid is placed in
the receiving syringe, another
in the injecting syringe, and
the current is measured on the
ammeter. Then the solution in
the injecting syringe is gra-
attery dually fed into the receiving
syringe, and any changes in the
current are noted. Conductance,
the reciprocal of resistance,
may be calculated from the
Ammeter
-272-
current and voltage:
»"f
mhos
R
To Gas Supply
(ii) Solutions which may be tested in this apparatus include water in the
receiving syringe and salt solution or HC1 solution in the injecting syringe;
dilute H2SO4 in the receiving syringe and Ba(0H)2 solution in the injecting syringe;
and dilute HC1 in the receiving syringe with NaOH in the injecting syringe.
(iii) This device, with one modification, may also be used to investigate the
variation of conductance as a
gas is bubbled into a solution.
The injecting syringe is removed
and replaced with a section of
plastic or rubber tubing that
connects the remaining syringe
to a gas source. For example,
the syringe is filled with a
limewater solution, and the
current is noted on the ammeter.
Then CO2 is passed through the
limewater, and the change in
current as well as the change in color of the solution can be seen. Phenolphtha-
lein can also be added to the limewater initially, and the color change from red
to clear will indicate the neutralization has occurred.
Battery
Ammeter
-273-
F2. Constant Volume Conductance Device
(3) Injecting
Syri nge
(2) Extracting
Syringe
(4) Wire
a. Materials Reguired
Components
(1) Container
(2) Extracting
Syringe
U Items Reguired
1 Jar with Lid (A)
Plastic Disposable
Syringe (B)
Rubber or Plastic
Tubing (C)
Dimensions
Capacity approxi-
mately 200-250 ml
Capacity approxi-
mately 20 ml
Diameter to fit
syringe nozzle; length,
about 1 cm shorter
than jar height
-274-
(3) Injecting
Syringe
(4) Wire
b. Construction
(1) Container
Plastic Disposable
Syringe (D)
Insulated Wire (E)
Holes for
Wires
Holes for
Syringes
Capacity approxi-
mately 20 ml
Diameter 0.3 cm,
50 cm long
Puncture four holes in the jar
lid (A) . Make the two outside
holes about 0.5 cm in diameter
to accommodate the syringe
(B,D) nozzles. Make the two
inner holes about 1 - 2 cm apart
and 0.4 cm in diameter, to
accommodate the insulated wire
(E) .
(2) Extracting Syringe
(3) Injecting Syringe
Push the nozzle of a plastic,
disposable syringe (B) through
one of the outer holes in the
jar lid. Attach the rubber or
plastic tubing (C) to the
syringe nozzle from the inside
of the lid.
Push the nozzle of a second
plastic, disposable syringe (D)
through the other outer hole
in the jar lid.
-275-
(4) Wire
Syringes
oo/\r>n
Strip 5 - 7 cm of insulation
from one end of each wire (E) .
Push each stripped end of wire
through the inner holes in the
jar lid, from the outside of the
lid. Allow about 8 - 9 cm of
each wire to extend from the
inside of the lid.
c. Notes
(i) In order to use this apparatus to investigate variations in the conductance
of a solution as its composition (but not its volume) is changed, the wires from
the container must be connected, in series, to a 1.5 volt battery and an ammeter.
[See diagram, Note (i), XII/F1.] A solution, such as water, is placed in the con-
tainer. A second solution (concentrated salt solution, for example) is placed in
the injecting syringe and the lid placed on the jar. Current is measured; then a
measured amount of solution from the injecting syringe is added to the container,
the solution mixed well, and volume of solution egual to that added to the con-
tainer is withdrawn with the extracting syringe so that the electrode depth is
unchanged. Current is again measured, and conductance calculated as described in
Note (i), XII/F1.
(ii) This eguipment is adopted from Andrew Farmer, "The Disposable Syringe —
A Rival to the Test Tube?," School Science Review, CLXXIV (1969), 34-35.
-276-
BIBLIOGRAPHY
A number of texts have proved to be extremely valuable references to the
Inexpensive Science Teaching Equipment Project, and these are listed below.
American Peace Corps, Science Teachers' Handbook,
(Hyderabad, India: American Peace Corps, 1968) .
This handbook contains many ideas for improvising
science teaching equipment.
Association for Science Education, The School Science
Review, (London: John Murray) .
A quarterly journal containing articles on
science experiments and equipment in all the
sciences at all school levels.
Association for Science Education, The Science Master's
Book, Part 2 (Chemistry) Series 1-4, (London: John Murray).
These materials, selected from The School Science
Review, describe apparatus and experiments for a
wide range of chemistry activities.
Coulson, E. H., A. E. J. Trinder, and Aaron E. Klein, Test
Tubes and Beakers: Chemistry for Young Experimenters, (Garden
City, New York: Doubleday and Company, Inc., 1971) .
This book describes simple apparatus and experiments
for youngsters in a home laboratory.
Bowker, M. K., and A. R. D. Hunt, Making Elementary Science
Apparatus, a Handbook for Teachers in Tropical Areas, (London:
Thomas Nelson and Sons, Ltd., 1968) .
This book outlines instructions for construction
and use of inexpensive, elementary science apparatus.
The Portland Project Committee, Teacher Guide, Chemistry of
Living Matter, Energy Capture, and Growth, (Portland, Oregon, U.S.A.:
The Portland Project Commiittee, 1971) .
This guide is one of a three-year sequence integrating
biology, chemistry, and physics into one secondary
science program. Student guides are also available.
Richardson, John S., and G. P. Cahoon, Methods and Materials
for Teaching General and Physical Science, (New York, Toronto, and
London: McGraw-Hill Book Company, Inc., 1951) .
This guide describes investigations and laboratory
techniques for secondary level physics and chemistry.
-277-
United Nations Educational, Scientific, and Cultural Organization,
UNESCO Source Book for Science Teaching , (Paris: UNESCO, 1962).
This book, recently revised, contains many simple
ideas for teaching-science at a. relatively
elementary level.
In addition to the above texts, the materials from a large number of projects in
the files of the International Clearinghouse on Science and Mathematics Curricular
Developments at the University of Maryland have also been particularly valuable.
Further details of these projects may be found in:
The Seventh Report of the International Clearinghouse on
Science and Mathematics Curricular Developments, 1970. (College
Park, Maryland, U.S.A.: University of Maryland, 1970) .
This is a source of information on curriculum
projects throughout the world, and indicates
materials available, project directors, publishers,
etc. The Eighth Report will be available in late
1972.
-278-
ALPHABETICAL INDEX
Air Composition Device
Alcohol Burner, Modified
Alcohol Burner, Simple
Ammeter, Hot Wire
Ammeters (See Galvanometers)
Anesthetizing Chamber
Aperture/Slit Combination
Aquarium, Breeding
Aquarium, Jug or Carboy
Aquarium, Plastic Bag
Aquarium, Quickly Made Demonstration
Aspirator
Aspirator
Baermann Funnel
Balance, Compression Spring
Balance, Current
Balance, Equal Arm
Balance, Extending Spring
Balance, Micro-
Balance, Pegboard
Balance, Rubber Band
Balance, Simple Beam
Balance, Single Pan
Balance, Soda Straw
Balance, Spring
Balance, Spring Lever
Ball-and-stick Models
Basket Sieve
Bath, Sand
Bath, Water or Steam
Battery, Simple
Beaker
Beating Sheet
Beehive Shelf
Bell Jar
Berlese Funnel
Bi-metal Strip
Page
CHEM/2 66
CHEM/40
CHEM/3 8
PHYS/255
BIOL/261
PHYS/113
BIOL/147
BIOL/146
BIOL/148
BIOL/145
BIOL/103
CHEM/117
BIOL/114
PHYS/12
PHYS/261
PHYS/24
PHYS/9
PHYS/22
PHYS/17
PHYS/5
PHYS/8
PHYS/32
PHYS/20
PHYS/36
PHYS/2
CHEM/193
CHEM/127
CHEM/18 8
CHEM/18 9
PHYS/185
CHEM/109
BIOL/101
CHEM/173
CHEM/111
BIOL/117
CHEM/59
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Bird Trap, Potter
Blowpipe for Charcoal Block
Bottle, Specific Gravity
Bottle, Wash
Bottom Sampler
Box Trap, Simple
Bulb Holder with Bulb
Burette
Burette and Ring Stand with Attachments
Burner, Candle
Burner, Charcoal
Burner, Fuel System for Gas-
Burner, Gas
Burner, Modified Alcohol-
Burner, Simple Alcohol-
Butterfly Net
Cage, Ant Observation
Cage, Cockroach
Cage, Cylinder
Cage, Glass
Cage, Glass Jar
Cage, Housefly
Cage, Jar
Cage, Wire
Cage, Wooden Frame
Candle Burner
Carbon Dioxide Production Chamber
Cart, Elementary
Cart, Heavyweight
Cart, Lightweight
Cell, Chemical
Cells, Dry Cell Holder with
Centrifuge
Centrifuge, Hand Drill
Chamber, Transfer
Charcoal Burner
Charles' Law: Volume/Temperature Device
Chemical Cell
Chromatographic Device
Chromatography Apparatus, Liquid-Column
BIOL/126
CHEM/191
CHEM/69
CHEM/114
BIOL/82
BIOL/119
PHYS/191
CHEM/61
CHEM/90
CHEM/35
CHEM/36
CHEM/43
CHEM/4 9
CH EM/40
CHEM/38
BIOL/94
BIOL/173
BIOL/163
BIOL/167
BIOL/176
BIOL/159
BIOL/165
BIOL/169
BIOL/185
BIOL/180
CHEM/35
BIOL/269
PHYS/61
PHYS/75
PHYS/66
PHYS/177
PHYS/180
CHEM/153
CHEM/149
BIOL/226
CHEM/36
CHEM/252
PHYS/177
BIOL/255
CHEM/237
-280-
Chromatography Device, Horizontal Paper
Chromatography Device, Horizontal Paper
Chromatography Device, Horizontal Paper
Chromatography Equipment, Vertical Paper
Chromatography Equipment, Vertical Paper Strip
Circuit Board
Clamp, Wooden Pinch
Clamp, Wooden Screw
Cleaner, Test Tube
Clock, Classroom
Clock, Water
Collapsible Heating Stand
Coil with Cores, Multipurpose
Composition of Air Device
Conductance Device
Conductance Device, Constant Volume
Condenser
Cone Sieve
Cover Slip, Glass Slide and
Crystalline Packing Models
Culture Flask
Current Balance
Decade Resistor
Deflagrating "Spoon"
Demonstration Thermometer
Dessicator
Diffraction Holes
Diffusion Chamber
Diffusion Device, Gas
Diffusion Device, Liquid
Dish, Petri
Dissecting Needles
Dissecting Pan
Distillation Apparatus, Condenser
Distillation Apparatus, Simple
Double Bond Structures
Dredge
Dropper
Dropper
Dropper /Pipette
CHEM/224
CHEM/22 6
CHEM/22 8
CHEM/230
CHEM/234
PHYS/195
CHEM/78
CHEM/80
CHEM/179
PHYS/52
PHYS/44
CHEM/8 8
PHYS/235
CHEM/266
CHEM/270
CHEM/2 73
CHEM/138
CHEM/12 6
BIOL/30
CHEM/217
BIOL/214
PHYS/261
PHYS/209
CHEM/177
CHEM/57
CHEM/181
PHYS/137
BIOL/258
CHEM/255
CHEM/254
CHEM/113
BIOL/39
BIOL/51
CHEM/138
CHEM/136
CHEM/207
BIOL/60
BIOL/49
CHEM/66
CHEM/242
-281-
Dry Cell Holder with Cells
Dryer, Electric Lamp
Drying Tower
Dynamo/Motor
Elasticity Device
Electrolysis Apparatus
Electroplating, Mirrors and
Enzymatic Reaction Chamber
Expansion Device, Gas
Fermentation Tube, Balloon
Fermentation Tube, Durham
Fermentation Tube, Syringe
Filter
Filter Flask, Suction-
Flame Test Wire
Flask Generator (Gas)
Flask, Light Bulb
Flask, Suction-Filter
Flasks, Volumetric
Forceps
Forceps
Fuel System for Burners, Gas
Funnel, Baermann
Funnel, Berlese
Funnel, Glass Bottle
Funnel, Separatory
Galvanometer, Elementary Moving Coil
Galvanometer, Elementary Tangent
Galvanometer, Moving Coil
Galvanometer, Repulsion Type
Galvanometer, Tangent
Galvanometer with Multipurpose Coils, Moving Coil
Galvanometer with Shunts, Moving Coil
Galvanometer with Shunts, Tangent
Gas Burner
Gas Burner, Fuel System for
Gas Collection Device, Plant
Gas Collection Device, Seedling
Gas Diffusion Device
PHYS/180
CHEM/18 5
CHEM/18 3
PHYS/217
PHYS/102
CHEM/145
PHYS/116
BIOL/263
PHYS/103
BIOL/247
BIOL/248
BIOL/249
PHYS/128
CHEM/12 9
CHEM/17 6
CHEM/165
CHEM/107
CHEM/129
CHEM/68
BIOL/48
CHEM/72
CHEM/43
BIOL/114
BIOL/117
CHEM/110
CHEM/132
PHYS/266
PHYS/246
PHYS/285
PHYS/249
PHYS/272
PHYS/292
PHYS/296
PHYS/276
CHEM/49
CHEM/43
BIOL/265
BIOL/267
CHEM/255
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Gas Expansion Device
Gas Generator, Flask
Gas Generator, Kipp's
Gas Generator, Simple, and Collecting Apparatus
Gas Production and Collection Device
Gas Reaction Chamber
Gas Solubility Device/Reaction Rate Chamber
Gauze Wire
Generator, Micro-
Geometric Structures, Models
Glass, Measuring
Glass, Watch
Glassware, Light Bulb
Glassware Technigues and Accessories
Grappling Bar
Grappling Hook
Growth Chamber, Plant
Heating Shelf
Heating Stand, Collapsible
Holder, Multi-purpose Design
Holder, Test Tube
Hydraulic Press
Hydrometer
Incubator, Egg
Incubator, Microorganism
Indicator, Displacement Type Oxidation
Indicator, Membrane Type Oxidation
Indicator, Oxidation Rate
Inoculating Needles
Insect Collector, Night Flying
Insect Spreading Board
Interference Strips
Jar, Bell
Killing Jars
Kinetic Theory Model
Kipp's Generator
Kymograph
Lenses and Prisms, Optical
Lens with Holder
PHYS/103
CHEM/165
CHEM/167
CHEM/163
CHEM/245
CHEM1268
CHEM/250
CHEM/82
CHEM/24 9
CHEM/215
CHEM/64
CHEM/112
CHEM/109
CHEM/1
BIOL/87
BIOL/85
BIOL/155
CHEM/83
CHEM/8 8
CHEM/73
CHEM/7 6
PHYS/96
PHYS/108
BIOL/200
BIOL/219
CHEM/2 60
CHEM/2 5 8
CHEM/262
BIOL/218
BIOL/105
BIOL/99
PHYS/138
CHEM/111
BIOL/96
CHEM/220
CHEM/167
BIOL/234
PHYS/121
PHYS/130
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Light Bulb Glassware
Light Bulb Glassware, Rack for
Light Bulb Glassware, Stand for
Light Source
Liquid-Column Chromatographic Apparatus
Liquid Diffusion Device
Magnetic Field Apparatus
Magnetic Field Apparatus with Multipurpose Coils
Magnetizing Coil and Magnets
Magnets
Magnets, Magnetizing Coil and
Magnifier, Illuminated Hand
Magnifier, Water Filled
Magnifying Glass, Water Bulb
Manometer
Masses, Box of
Membrane-type Oxidation Indicator
Measuring Glass
Metal Sheet Shelf
Microbalance
Micro-generator
Microscope, Adjustable
Microscope, Glass Stage
Microscope, Hand-Held
Microscope, Match Box
Microtome, Hand
Mirrors and Electroplating
Model, Kinetic Theory
Models, Ball-and-stick
Models, Crystalline Packing
Model Units, Molecular
Mortar and Pestle
Motor/Dynamo
Motor, Simple
Moving Coil Galvanometer
Moving Coil Galvanometer with Multipurpose Coils
Moving Coil Galvanometer with Shunts
Multipurpose Coil with Cores
Multipurpose Design Holder
Multipurpose Stand
CHEM/107
CHEM/100
CHEM/102
PHYS/111
CHEM/237
CHEM/254
PHYS/238
PHYS/241
PHYS/231
CHEM/125
PHYS/231
BIOL/7
BIOL/2
BIOL/3
BIOL/251
PHYS/30
CHEM/258
CHEM/64
CHEM/7 4
PHYS/22
CHEM/249
BIOL/24
BIOL/14
BIOL/19
BIOL/21
BIOL/35
PHYS/116
CHEM/22
CHEM/193
CHEM/217
CHEM/198
CHEM/120
PHYS/217
PHYS/212
PHYS/285
PHYS/292
PHYS/296
PHYS/235
CHEM/73
CHEM/98
-284-
Needles, Inocul ating
Net, Butterfly
Net, Dip
Net, Lift
Net, Plankton
Optical Screen with Holder
Optical Board and Accessories
Oxidation Indicator, Displacement Type
Oxidation Indicator, Membrane Type
Oxidation Rate Indicator
Pendulum, Simple
Pestle, Mortar and
Petri Dish
Pipette
Pipette/Dropper
Pipette, Transfer
Plankton Net
Plant Growth Chamber
Plant Press (Field Type)
Plant Press (Laboratory Type)
Press, Hydraulic
Prisms and Lenses, Optical
Pulse
Pump
Rack for Light Bulb Glassware
Rack, Bamboo Test Tube
Rack, Wooden Test Tube
Rate Indicator, Oxidation
Reaction Chamber, Gas
Reaction Rate Chamber/Gas Solubility Device
Rectifier, Silicon
Rectifier (2 Plate) , Sodium Carbonate
Refraction Model Apparatus
Relaxing Jar
Reptile Hook
Resistor (Carbon) , Variable
Resistor, Decade
Resistor (Nichrome) , Variable
Respirometer
BIOL/218
BIOL/94
BIOL/54
BIOL/71
BIOL/65
PHYS/124
PHYS/119
CHEM/260
CHEM/258
CHEM/262
PHYS/50
CHEM/120
CHEM/113
CHEM/67
CHEM/242
BIOL/224
BIOL/65
BIOL/155
BIOL/140
BIOL/142
PHYS/96
PHYS/121
PHYS/49
CHEM/243
CHEM/100
CHEM/103
CHEM/105
CHEM/2 62
CHEM/2 68
CHEM/250
PHYS/168
PHYS/162
PHYS/126
BIOL/98
BIOL/132
PHYS/202.
PHYS/209
PHYS/204
BIOL/270
-285-
Respirometer
Ring and Burette Stand with Attachments
Ripple Tank
Ripple Tank Accessories
Sand Bath
Scalpel, Razor
Scalpel, Strapping
Scissors
Screen, Hand
Screen with Holder
Screw Clamp, Wooden
Seine, Two-Man
Separatory Funnel
Shelf, Beehive
Shelf, Heating
Shelf, Jar Cage
Shelf, Metal Sheet
Shunts, Tangent Galvanometer with
Shunts, Moving Coil. Galvanometer with
Sieve, Basket
Sieve, Cone
Sieve, Soil Organism
Single Bond Structures
Slide and Cover Slip, Glass
Slit, Adjustable Single
Slit/Aperture Combination
Slits, Fixed Single and Double
Slits, Multiple
Snare
Soil Organism Sieve
Source, Light
Spatula
Spatula, Test Tube Cleaner or
Specific Gravity Bottle
Specific Gravity Device
"Spoon', Deflagrating
Spreading Board, Insect
Spring Balance
Spring Balance, Compression
Spring Balance, Extending
BIOL/273
CHEM/90
PHYS/81
PHYS/90
CHEM/18 8
BIOL/43
BIOL/41
BIOL/45
BIOL/56
PHYS/124
CHEM/80
BIOL/68
CHEM/132
CHEM/173
CHEM/83
BIOL/161
CHEM/174
PHYS/276
PHYS/296
CHEM/127
CHEM/12 6
BIOL/110
CHEM/203
BIOL/30
PHYS/136
PHYS/113
PHYS/134
PHYS/133
BIOL/130
BIOL/110
PHYS/111
CHEM/178
CHEM/17 9
CHEM/69
PHYS/107
CHEM/177
BIOL/99
PHYS/36
PHYS/12
PHYS/9
-286-
Stain Bottle
Staining Vessel
Stand, Collapsible Heating
Stand for Light Bulb Glassware
Stand, Multipurpose
Stand with Attachments, Ring and Burette
Steam or Water Bath
Sterilizer
Stick Models, Ball-and-
Still, Water
Stoichiometry Device
Strapping Tripod
Strip, Bi-metal
Stroboscope
Structures, Double Bond
Structures, Geometric
Structures, Single Bond
Structures, Triple Bond
Suction-Filter Flask
Sun Dial
Switch
Tangent Galvanometer
Tangent Galvanometer, Elementary
Tangent Galvanometer with Shunts
Tank, Ripple
Techniques and Accessories, Glassware
Temperature/Volume Device: Charles' Law
Terrarium, Glass
Terrarium, Simple
Test Tube Cleaner or Spatula
Test Tube Holder
Test Tube Rack, Bamboo
Test Tube Rack, Wooden
Test Wire, Flame
Thermometer, Demonstration
Thermostat
Timer, Ticker Tape
Tower, Drying
Transformer, Iron Wire Core
(6 volt output, 120 volt mains)
BIOL/33
BIOL/31
CHEM/8 8
CHEM/102
CHEM/98
CHEM/90
CHEM/18 9
BIOL/215
CHEM/193
CHEM/141
CHEM/2 63
CHEM/8 6
CHEM/59
PHYS/93
CHEM/207
CHEM/215
CHEM/203
CHEM/213
CHEM/129
PHYS/41
PHYS/193
PHYS/272
PHYS/246
PHYS/276
PHYS/81
CHEM/1
CHEM/252
BIOL/153
BIOL/151
CHEM/179
CHEM/76
CHEM/103
CHEM/105
CHEM/176
CHEM/57
BIOL/207
PHYS/56
CHEM/183
PHYS/140
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Transformer, Sheet Iron Core
(12 volt output, 120 volt mains)
Transformer, Variable Output
(120 volt mains)
Trap, Funnel
Trap, Piling
Trap, Potter Bird
Trap, Simple Box
Trap, Soil Insect
Triple Bond Structures
Tripod, Strapping
Tripod, Tin Can
Tripod, Wire
Tweezers
Units, Molecular Model
Vacuum Apparatus
Vasculum
Vertical Paper Chromatography Eguipment
Vertical Strip Paper Chromatography Eguipment
Vivarium
Voltmeters (See Galvanometers)
Volume Determinator
Volume/Temperature Device: Charles' Law
Volumeter
Volumetric Flasks
Wash Bottle
Watch Glass
Water Glass
Water or Steam Bath
Water Still
Wing Tip
Wire Gauze
Wire Tripod
Wormery, Box
Wormery, Jar
PHYS/147
PHYS/153
BIOL/76
8IOL/73
BIOL/126
BIOL/119
BIOL/112
CHEM/213
CHEM/8 6
CHEM/84
CHEM/8 7
CHEM/72
CHEM/198
PHYS/99
BIOL/136
CHEM/230
CHEM/234
BIOL/191
PHYS/105
CHEM/252
BIOL/244
CHEM/68
CHEM/141
CHEM/112
BIOL/90
CHEM/18 9
CHEM/141
CHEM/54
CHEM/82
CHEM/87
BIOL/171
BIOL/168
Live Music Archive
Librivox Free Audio
Metropolitan Museum
Cleveland Museum of Art
Internet Arcade
Console Living Room
Books to Borrow
Open Library
TV News
Understanding 9/11