Modified limit tests for chlorides and sulphates.

Modified limit tests.

1. g M.aCIJhusl!ldJla.n:a HM~ lnmm PII.D
MODIFIED UADTTEST FOR CHLO·lUDES
Prin-csiptr.: A1otlified lim~l tesl· is perf onned: jf" die li·mil te!!i\s for a .~ample (Colon~
l'orupoUJ1d) caiwot b1,;• do:1:1.~ b~· oonnal 1n1,;·tboo~ fo.r t'!Xlimph.:~ pulas...,.lnrn
pcnUW1;~aoate ~ dt"-ooloiuised b~· boil.inl, -.,ith e:thnnot filtered w. 11!010\·e
precipitated mang., nese dioxide and the filtnlle is subjerl~ to th~ t~t
i,t i:!t ooSiNJ 11pon the· chflmii:'i~1 teadion hetween sih~Pr n1Cr11h• anrl M1!11'hlt5 ddoridf's to
uhtain. :Sih·er l"hluride· :in pre.s~nce or dilutf'! n.ilric =icid. ]'he ~it.i.•~r t·hlorid~ prod110l"d in
th~· pn~DC"e ol clilu~~· niuic ac·id n~kc_s llu:. t,i.sl ~l"tiun lnrbid~ 1 bt: cltcnt ,of
tllthtctity/opalesceliltT ri.cpl'ndini upon 'the .nmonnt of chlorirk )lfelieht ilil the
snb&mnre is oomrpanid with a standard CII.J'bidJ[)·/opnlescenre produced ~-MidHion
of sih"l"'r nitrnt~ to~• sl~-1nd~~rd sol~1tinm hH\ing a kncnvn mnm.mt of rhlorid, iitn•I lhti:
snn1-.· ,·oh,m..-ol diltill] 11ilril
1 1u.:Mi u.~ u.,...._I it1 th~ lest riollllfflfl. [f I bt!
turbklit)•/~hl'T from th~ sAllllJ[e bas bt..i.en less tb ~u 'th~ standatd sohnioD, lhi•
sampltl' will ~ th11 limi.t tt-~t and vite '-rt!l'!ial. Dih1t~ nitric· a-c·id iJ. wwd in lbe limit
hi;~, or ,~h1ri,w tu mi:1k~ St)1nlinn sddit .1nd -"hkh ~~, ... ~ ~ih·t11
1
~-:nttlTidr rl'f'ripililtf' ltli
rnnke solution l11rbitl 11t the ~nd of procestC.
Reacdons:
~-,cw• AgNO:,
er ... .AgNol
AgCI ' • ~aN01
[HI. HN0
3
__ ....., AgC!' • N03
2 KMnOt i, 3 C~H=.OH ~ 3 CH~~.C.HO ., 2KOH • 2 ldnO: • 2H
2O
Pn~cetltU'e:
Pnp•~atio» of T~tit Solulio11 (D-f nO,J:: Oissolvc. 1.5 g ~n 50 ml of di~til ~ed
water,, heal on a water-bat~ Ulld ai:l.d gradual~· 6. ml. of ethanol (95%). rool"' dilnt~ to
6fl rnl. \!\1th dis.tililed water ;md filter-
Take tn--o 50 mL XessJN" Cylinders. T;the'E otu~ as "'Test"' and the. atber-as -Sbodard".

2. 1"1."Bt __ I Starndard
Tale 4n ml. of thP =•hove IPBI ~nlutinn f l'nkt-10 mt at rhlnrld(II ~,r.ndartl ~
i.n. Ni1..ta'i.l.bn-cy·Hnder. :st1IHU,~n (2sn ppn, CU and 5 :nil., nf
\1i~atl~r
Addi.a 1nl.1ofdihtte-nilrit acid
Di1t1l~ to• 50 tnL \'ii1th disliDed ·wat~r
Add 1.0 ntL of mltne llitrn: acid
ffilute lo 50 tnL with ~llW ,~·al~t
Add l.O mL or O. l :,i,r ~~'lo, solu Lion
Slir 9n1n,,edun~'ly w1lh pJLW rod 11ntl c.llo\'I I.a ~Land (or 5 mi nut~~ r:ol~•~d
[mmJil')it
Ohsein1111ion: Thie opajesceare produce-in sample :solutio:o should not be greater
th1u1 struidnrd solu1ion. lf opalescenC'e produ.ce--5 in sample 50hUion is Jes:s th011 the
1~ C.b.loride standiml solution (250 ppm 01): JII>ilt1t'e 50 mL of 0.0824%
w/\' ~ohttjon of sodinm dtloridt-lo I.OtJ m.L \Vilh db1il~lNI. \'Iltn.
r,. DUute bl,ri<' Pd,d: rtilute 1 ft)6 lnL of cCJn~. Niltk add in s11tticient dL~I iUIMt
Willter to prndut"f! ioo m L
3. O. '.ll. M Silver nitrate: Dissolvf! 1. 7 M. of silver nitrate to .100 mL wilh di5tilloo
4. lh~ q=uantjtQth-·e and ,emi-qunti1ath~ delt1rmh1~tion of eblorid"'
5. Trus. test~ But used .fur walc.t-imm.L~-iblc liqu.i&.
(t. 1'he o~ce, in tht-sample aud 5landai·d 5ohation i;s rompared by kec-p~
lh~ Ne~ster cylindtin ,-gainsl dttrk biKkK:found and o~rvin~ -side by sidli.

3. M.ODIFJED
1 LmlIT THf!,"T FOR SULPEIATES
llrinctple: l'.!c"li Fwd I imit l:est ~ ~rfurnied: i r ·th~ I imit Im~ r~,., a Mmpl~ (Col(n~red
cumpound) ~an.not :be, oont• by 11or-1na.t tnE.Jl1~ud. Fur en.mpfo. polns~inm
pe11nangaru1tc is de-colourised br lxrilillJ,; ,\'uh ethanol. filtered to r·e111ovl?
preeipitr.ted manpnese dioxide !IDd the Dltrnte is subject~ 10 the test.
'J11e lin~il tfSt for .~ulphnl~ is ~d.rriNi nut tH1 th~ b~~is 1)f tht1 Mnrlion ~tWetin ~..rl11,m
chlc,ride and soluble s.u)_phates in the presen~ of acetie acid .. lben. the comparison or
tl1e nu·bidi~· prod~ by a Kl"·eo amoull.t of the sabslauce is do.oo v.,ith a stillldtu-d
t•~rbidit?-' ohtaihl"d frum a knO\il ~n\ount nf s11lphnt~. Th'-' hnrh1n1 thlorid~ hM ~n
repLlced by ba.riwn sulpha1e rea1ent wbtd.1 is havibg bariwn mloride. swpbt=-te ... ffee
alcohol, and a solution of ]XJt::issium ~ulphate_ llatassiu m sulphate has 'been adde-d t:o
i~:n·rc·a&i: Uu ... semith'il)" of toe t~t Th-.· iouk ,"01u-c ... ntrations iH lht· m:.J(iun111~ bt."4..
1n
90 nd,ium:Ni that the-soh1hility prodnct of bn.tinu1 1ul.11lutt.11 Reh ~ed. and. tlH~ \. .. ry
smnll illnoll.Jll of barium ~--uJphate present in the re.a,gent acts as ai ~g agent for
precipit al ioo of h."lrill f'f1 ~1.1:lpbate. i r !!;11lphL11e he present j 1'!11 1 he snbsl.anre lli!ldflf t~t
All, ihul b~lr•s lo pm·~nt 8icurwr•:4Jl't u r.tHiu~1 n nrl tihu[iil. pmdurn a mont una ftwm
opalt..i;s(~t!'.lk"l'/lw-bidity .... ; ~li11.: ildd .he:i-lps to tnr~k~· solutwn ut·idk-and bariUD.1 stdph.att•
precipitate. f~ is in.~Jable "il:icb gives mrbidity/opal~-
lleactio-nB:
Air~.Ku:IJ
K2SD._ • BaCl1 ___ .., SaSO,L+ --2 KCl
~ Arnlc~ci.d -
SO.f .., BaCl~ ~ HaSQ_.,J + 2 Cl

4. PROCEDURE
Preparation of Test Solution (IOfnO.
1
): Dissolve 1.5 gin 50 n1L of distilled
water, heat on II water-bath and acid gradually 6 mL of ethanol (95%), cool, dilute to
60 mL with distilled water and filter.
Take two 50 ml. Nessler Cylinders. Label one as "Test• and the other as ·standard'.
Test Standard
Take 10 m L of the above test solution !Mb: 15 ml of sulphate standard
in Nessler cylinder. solution and 15 n1L of distilled water
in a Nessler cylinder
Add 0.15 1nL of 5.0 !VI acetic acid Add 0.15 mL of 5.0 M acetic acid
Add 2.5 ntL of barium sulphate Add 2.5 ml of bariun1 sulphate
reagent 1·eagent
Add sufficient distilled water to Add sufficient distilled ,vater to
produce 50 nil. produce 50 nil.
Stir in1mediately with glass rod and allo\v to stand for S n1inutes protected
fron1 light
bservation: The opalescence produce in sample solution should not be greate ·
than standard solution. If opalescence produces in san1ple solution is less than the
standard solution, the sample will pass the lin1il lest for sulphates and vice-versa.
Note:
1. Barhun Sulphate Reagent: ~1ix. 10 mL of 25% w/v solution of bari111n
chloride and 15 mL of eth11nolic sulphate standard solution ( 10 ppn1 SO
4
) and
allow standing for 1 minute. It should ahvays be prepared fresh.
2. Sulphate standard solution (600 ppm S0
4
): Dilute 60 ml. of a 0.181%
w/v solution of potassium sulphate in distilled water to 100 mL ,vith the san1e
solvent.

5. 3. Ethanolic sulphate standard solution (to l'l'lll S04): Dilute 1.0 ml of a
0.181% w/v solution of potassium sulphate in ethanol (30%) to 100 ml 1,1th
the same solvent.
4. 5.0 M Acetic acid: Dilute 28.5 mL of glacial acetic acid in sufficient distilk-d
waler to produce too ml.
5. TI1is tC'st is nnt uscrl for water-innnis-cihlc liquirls.
6. ·111e opaleseence in the sample and standard solution is t'Ompared by k<-.,ping
the Kessler cylinders against dark ba<:kgrnund and obser.fog side by side.