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If, instead, 1 cc of the. .solution is to contain n rumple, definite, weight, n

, IOOOX58.>If> /t , .. , .

grn, of chlorine, each liter must contain ....... ,.r ,,, gm of Hodium chlo-

ride. In this cane w may conveniently In* (UHI5 grn, Whatever its value, n
Is the "chlorine factor", /'Vi (nee page* 5) of thw notation.

Weigh thewilt carefully on counterpoised glasnen and diwnolve in chloride-
free wafer in a calibrated flank, dilute to the tnark and mix thoroughly.

(r) l*ulax*ium ('hromnte.- ..... -Prepare 50 cc of a 5-pcr rent notation of potm-*-
Hium ciiroinate and <lrop into it wilver nitrate, solution until a perceptible
coloration, due to hilver chrornat<», in obtained, thusuhowin^ that nil chlorides
have been removed. Allow the precipitate to settle and then dcciutt into n
bottle that can be ntopprred.

Standardization.- ..... -Pipi'tte 25 w cif the ^o<litiin chloride Hnlntinn into n
2(K)-cc. c'awserole, f»r into a beaker which is placed ov**r a, white surface.
Dilute with 25 cc of chloridi'-fr«*e distilled wafer, add I rr of chromafc
solution and then add the Hilver nitrate Holution from a, burette, Mtirrtfttf
conHtanfly, until the lirnf permanent purple or reddtnli tint IM obtained.

AH each drop of mlver nitrate Kohition w added, u, purple preeipitaf** in
produced. Neiir tlte beginuin^ of tin* titratton thin diMuppeura irttfucdmtf^y
after mixing but townrd fh<* iitti^h it penii^its for a longer fiun
liehavior werven im a warning of the npproueh of the **n«i point.
firnt indication t»f H fnint but perfunnent color, riiir*** d«iwn th<*
the beaker or ca<HMen*h* with dint illerl water, read th<* buri*f te and t lien ruftft
the reading by fuhiifig iiimther drop of silver nitrntt* ifoluttim* w-hich f4i*H
deepen the color. When this hu.8 t»c<*urred, record the volume fir«f. tn»fe»i
the end point. HttiHe the eaNserole iimi repent ti»e tttrution with is.
portion of Modiutn ehlorid*' Hohttion, until ugreentcnt in cibtnined.

If u tenth-nonniil solution «if niJver nitrate in de«ir«fd, tl»*4 liiidiuiiii chl«*rifl*«
solution will have bf»eii mitdi* to thin nonimlity. In thin <fn«e, u«e m miu!^ iff
the following wiiifil** retution: Thnt th«« mirrnnhtieM *if two liniiif WIIH are
inversely HM f!i«* %*i'ilniiii*-M f<»ttiic2 fn be i*^(iiivfili*rtt to each other, Hstif*fw«e
thut 25 cc of fcnth-itoniml chloride nolution $-4 exitctiy tstrjit**d t»y *MJ*»
<:c*. f»f silver nitrntf* solution. The* nonimlity of the .«»ilver fi<4iifi«iii t« th*«n

25 N ...

«M tr • in Illlf^ ^lf* "«iilutmn ratio

^5!t, I «> llr

mnlity f art or"),

If the deeiniiil «yi'iti*in in to be twin! mid if tin* iKiditiiii chl*»ritle fioinUon
hfw been miide HO »/* to coiit-nirt f)»i2*ri gin in 25 r*% iyi {ibfive ^itgge.fifivi, flu*
dilution ntli'i for flu* «ih*er iijtriife wtlnlinn in iigiiiii flu* invrw nifift *if
equiviileiit voluftien, exactly II.H illiwf rnti'd in tin* prreediftiC |}nrngrn|i!t.

In thu ubovir #^niti|ile 1 <•<? of tin* xoitttion wo«M Iiii%+t* to t«« diltif^il to
1.0,15 cc, to make if. tenth-mtriiuil, 1IM) to Itl.lJj rc» I liter to !IW* re, i*f»»,
Upon the uMMiiftiptioft that tint mim of cirigtnn! ftolutiott uncl ftd*l*"d wnter
equnlH flu* vtilnirif* of diluted notation Inn luvtnmption ru»t strictly Brt'urat#%
although priii'tifiilly HO for HoIutiottH not i«orc cotieeiitriited tlmii f!iinif>)
35 i»c of wnter should lit! nddttd to <*n«fh liter of the utaitdurdtxitd witutioit of
thi« example.

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24,15

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