IOL. 13 (1955) ANALYTICA GHIMICA ACTA 3or

VOLUMZTRIC STUDIES IN OXIDATION-REDUCTION REACTIONS IV. OXIDATION WITH CHLORAMINE-T.

IODINE MONOCHLORIDE METHOD

JMLWA?;T SISGH ASD IiltISHhN Cl-IA~DEJI SOOD

NC)LL~ described the use of chloraminc-T as an oxidizing rcagcnt. Rurr2 used chlora- mine-T for the determination of trivalent antimony, and later for the determination of stannous tin. ToBIxcEK AND Svcrr.Altu h3 used it as a reagent for the potcntiometric determination of trivalent arsenic and antimony; bivalcnt tin and iron and fcrrocyanidc and iodide ions; and for the visual titration of trivalent arsenic and antimony, using methyl red as an indicator. KOIIAIIOWSK\’ et al. 4 have shown that chloramine-T can bc used as a volumetric reagent to replace the mom cspensivc iodine and less stable hypochlorite in the estimation of ferrocyanidc, hydrazinc and hypophosphite. SINGH

AND REIIXIANK~~ have used chloraminc-T for the cletermination of hydroquinonc, quin- hydronc, hydrazinc hydrochloride, potassium iodide, sodium bisulphitc and sodium nitrite by a potentiometric method. LEE o et al. used chloramine-T in the quantitative estimation of various organic sulphidcs. AI:ANAS’EV’ has shown that chloraminc-T is a suitable reagent for determining many organic compounds by oxidative volumetric procedure, using methyl red or indigocarminc as an indicator. SISGH et aL8 have used chloramine-T for the potentiometric estimations of vanilin, p-hydroxybenzaldchyde, benzaldchyde, salicylaldehydc, acetaldchyde, furfural, urea, oxalic acid, thiourea, glycerol and mannitol.

In the present investigation chloramine-T has been used for the volumetric deter- mination of potassium iodide, hydrazine sulphate, arsenious oxide, stannous chloride, mercurous chloride, tartar cmctic, potassium thiocyanate, and ferrous ammonium sulphatc.

In presence of hydrochloric acid these substances react with chloramine-T in accor- dance with the equations:

KI + CH,C,,II,SO,N(Na)Cl $- z HCl NJ-I,, + 2 CH,C,H,SO,N(Na)Cl As,O, + 2 CH,C,H,SO,N(Na)Cl + 2H,O SnCl, + CH&,H,SO,N(Na)Cl -t_ 2HCl H&l, -j- CH&H,SO,N(Na)Cl -t_ 2HCl SbaO:, _1- 2 CH&,H,SO,N(Na)Cl $- 2H,O 2KCNS + 6CH&,,H4S0,N(Na)C1 + 8Ha0

WeSO, + $H,C,H,SO,N(Na)Cl + 6HCl =

XC1 + NaCl + ICl + CH&H4S08NH, N, + 2 NaCl + 2 CH&,H4S01NHp As,O, + 2 NaCl + 2 CH&,H,SO,NH, SnCl, + NaCl + CH,C,H$O,NH, 2 H&l, + NaCl -l- CH&,H4SOaNHa Sb,O, -f s 2 NaCl + 2 CH&H4S0,NH, 2KHS0, + 2HCN + GNaCl +

6CH&,H4SOpNH, 2Fe,(SO,), + 2FeC1, -j- 3NaCl +

:-#ZH&H4S02NH,

‘Hcfcrcnces p. 304.

302 B. SINGH, K. C. SOOD VOL. 13 (1955)

EXPERIMENTAL

A known weight of each substance was taken in a conical flask ant1 about 25 ml of water, 25 ml of concentrated hydrochloric acid, 5 ml of o.ozM iodine monochloride and 5 ml of chloroform were added to it. The mixture was titrated against standard chloraminc-T solution. The reagent was added from a burette until the solution, which was colourcd with iodine, became pale yellow and the chloroform layer acquired a purple colour. The conical flask was stoppcrcd and vigorously shaken during the titration. Addition of small volumes of the chloramine-T solution was continued, shaking vigorously after each addition, until the chloroform layer was faintly viol&. Tim clrloraminc-T- was then added dropwise, with shaking after the addition of each drop, till the chloroform layer became very pale yellow. The end-point was very sharp.

In these titrations normality of the solution with respect to hydrochloric acid was kept bctwcen 4N to GN. Scvcral titrations wcrc performed in each cast. From the volume of chloraminc-T used, corresponding to the end-point in each titration, the amount of the substance was calculated. The results arc rccordcd in the following tables.

All the chemicals used in this investigation were of guarnntccd purity.

POTASSIUM IODIDE ----.-_._. _. ._ . _.. - ._._ --_ __._ ._._. -__ _ _ _. _ _--- . . _ _._ __ _ .__ _. ___

KI tokeu o.roooN cklovnmw~e-T ccscd KI /uunJ L: ml 6

_ ----... -__-____ ___. _ ._. . . _ __ ___. -_ . __._ -__-.. __.__ _ _ _ _ - .--___- -_ 0.0831 IO.00 0.0830 0.1496 18.00 0. 1494 0.1828 22.00 0. I8ZG

0.2244 27.00 0.224I

o.zGclo 32.05 o.zGGr --__ _-_._- ____--___~-_-__-_______-

TABLE II

lIYDRA%INE SULI’IIAIE -...---- --- -- - ------.-_.__ _ -.. _.___ - _ _--- __..___ -.. _-^- .._- -_ - . .._ _ _ _. ________-_ _.__.

N,II..H.SO, taker o.~oooN chlovamr~~e-‘T rtscrf NIN,.IIISO, /owed fi ml fi

--._.... _-___ -. . --._ _. __ __._ - .___ _. . --._. _ __ ._ _._ . . . _ _ o.oL+‘)o 15.x0 o.o.+g I 0.0720 22.10 0.0719 0.0878 27.00 0.0878 0.1043 32.10 0.X0.+)

O.IZOG 37.00 0.1204

TAHLE IL1

ARSENIOUS OXIDE

As,O. taken o.toooN chlovnmi,~c-‘T lued ml

.4s,q /oumI 89 R .--.--_ _---_--_-_-_ -._ - . -.- -___ -__

0.0496 10.00 0.0893

0.0495 X8.10 0.0895

0.1088 22 -00 o. x088 0.1339 27. x0 0.1588

0.1340 32.10 0.1588

--_~-~-_-~_--.--._. -. -_-- ___.. .-__-_ _ ^_ __ . _.

TAULE IV

STANNOUS CIILORIDIS ---- _ _ -_ _.

.SnGl,.o H.0 taken o.xoooN chkwaminc-T wed 6 ml

----.--. -. .- .-._ _.__.____-__ __________ __ _ 0.1129 10.00 0.2034 x8.00 0.2486 22.00 0.3048 27.00 0.4oG8 36QO5 _-___ --_

References p. 304.

. .---__ --.--_ ___. --__ SnOl,.a H,O found

lz - - -_- .- --_- _-. ._ 0.1128 0.2031 0.2482 0.3046 0.4oG7

-^- -_ _ _-__ -

IOL. 13 (1955) VOLUMETHIC STUDIES IN OXIDATION-REDUCTIOS HEACTIOSS IV 303

TABLE V

MERCUHOUS CIiLORIUE __--_----_~~_~__- --.------ _-____-_-___

H&Cl, fakrn o.roonN rhloratnwr.‘f usrrf C ml

__ ._,.__ -_.__-__ - --. __ -

o.agGr ? . _ _-- -. _ . _.

10 00 o.3542 15.00

o-5194 2100 0.6375 2 7.00 o-7555 32.00

TABLE VI

‘I’arlar.cmrlw tnkot 0.rooo.V chlorumhr ?‘ trsrd R ml

.._.--.. .._ .--.__- ._.._. ..--_ _-.__ _.--..-_. ._ _____ - ..__ _._.-. .__._._. _ _. o. I 670 10.00 0.3006 18.00 0.4’75 25.00 0.5343 3’2 00 0.0680 40 00

._-----.-_-__ -___.-_-____ __._ _ ____ __ -__--.__ _ __ - .___^_

TABLE VI1

- I’OCASSIU.\I TIIIOCYANAT1:

_ ____ _

o.roooN chlorumtnc-f urtrl rttl

Tnrlnr etnrllc /OlOkf P

_.-_--__ . _._-. .._-. .-_

0 1670

0*3005

o.4r7-l o.!i343 0 Wit)

--._.- _.- - _-_.-

. . -- ._.- _...__ -. . .._ - KCIiS /010u1

tz .--.-- _-_*~__.--_--.-_-__-__ _ -.-_.._. --- __-__- -----_ - --- _. .- -.__ -._ ---.- ---.__--._---_ 0 OIG2 10.00 O.OI62 o.org.+ 1800 0.021)2 o.o.loG 25.00 0.0405 0.0520 32.00 0.0518 0.0730 45.00 O.OiZi)

- ._.. _-.. .-_.-._ ..- ___

TABLlS Vl I1

FERROUS AhlhlONIUhl SlJI.I’IfA~E -----_-- -- . -. -.- _._ __ .- -__ __ . _ ..-__ __ _ __.. - . . _ . _ _ -_-

I;rSO.(NII,),S0,.611.0 o.roooN chlommwc-‘l’ rcwri taken

r:eSo,(NH,),So,.6ll,O /OlO,J

K ml R ----__A. -- -.-__-_-_-_- _---- ____.. -_--

0.2353 0.00 0.2353 0.3922 10.00 0.3gz.z 0.588q f5.00 0.5882 0.7880 20.10 0.7882 0.945a 24.10 0.9451

_..- -_-___ ._ ___. ^__ _. . _ . --.-_ _ ..__ _ _.. - _.

The results show that the substances given in Tables I to VIII can be determined quantitatively by the iodine monochloride method, using chloramine-T as oxidizing agent.

SUMMARY

Chloraminc-T has been used as an oxidizing agent in hydrochloric acid mediuni for the volumetric ‘estimations of potassium iodide, hydrazine sulphate, arsenious oxide, stannous chloride, mcrcurous chloride, tartar-emetic, potassium thiocyanate and ferrous ammonium sulphatc, using iodine monochloride as a catalyst and pre-oxidizer. Chloroform is used as an indicator. It is coloured pink owing to the liberation of iodine during the titration and becomes very pale yellow at thecnd-point because of the formation of iodine monochloride.

Rl%UMl?

La chloramine-T a 6tb utilis& comme oxydant, en solution chlorhydrique, pour le dosage volu- m&rique de l’iodure de potassium, du sulfate d’hydrazine, de l’anhydridc ars&ieux, du chlorure

References 9. 304.

3-l B. SISc;EI, I<. C. SOOD VOL. 13 (1955)

d’&lin(Il), du chlorure dc mcrcure(l), du tartratc d’antimonyle, du thiocyanatc dc potassium ct du sulfate de fcr(It) ct d’ammonium; on emploic le monochlorurc d’iodc commc catalyseur et pre- oxydant. Lc chloroforme scrt d’inchcatcur ; il SC colorc cn violet par l’iode lib&6 pendant la titration ct dcvicnt jaune pale au point final pat formation de monochlorurc d’iodc.

Das Chloramin-T wurdc in salzsaurcr LOsung ills Oxytlationsmittcl verwendct fIir die volumc- trischc 33cstimmung von Kaliumioclid, Hytlrazinsulfat, arscnijicr Siiure, Zinn (11) chlorid, Qucck- srlbcr (I) chlorid, Antimonyltartrat, Kaliumtliiocyanat uncl Eiscn (LX) - und Ammoniumsulfat. Man vcxwcndct das Jodmonochlorid als Kntalisator und voroxydicrcndcs Rfittcl. Das Chloroform dicnt nls Indikator; cs f!lrbt sic11 violet durch das wlhrcnd dcr Titration frci gcwortlcnc Jod und wird am Entlpunkt durch EJildung von Joclmonochlorid l~cll~cll~.

Rcccivccl l:clxuary I Ith, 1955