VOL. 14 (1956) ANALYTICA CHIhIICA ACTA 505

VOLUMETRIC STUDIES IN OXIDATION-REDUCTION REACTIONS

VIII. OXIDATION WITH CERIC SULPHATE FERROUS ETHYLENEDIAhIINE: SULPHATE &IETHOD

The salts of quadrivalent ccrium arc the most vcrsatik of the strong oxidizing agents, which may be used as standard solutions. CARAW,\Y AND OEWER~ showed that fcrrolls ct~lyIellcdi~trnine sulphatc, FcSO,, (CH,.NH,),S0,.4H,O, reacted stoichiometrically with ccric sulphatc which is commonly employed in oxidimctric titrations.

In acid medium ceric sulphatc reacts with ferrous ammonium sulphatc, cuprous chloride, potassium thiocyanatc, sodium thiosulpllatc, sodium nitrite, hydrogen peroxide, sodium oxaiate, hydroquinone and pyruvic acid in accordance with the equations :

C(yl-4 4.. Fe-f-2 -_t cc-k3 + Fe-i-3

ZCC-‘~~ + cu,+2 -> z&e+3 -/- 2Cu-f-2

GCc+a -+ CNS- _1- _c H,O --r Kc+” + CN- + SOI-” -j- 8H+ zCe+~ -+ zs*o,-” --5 zCc!+~ + s,o,-2 zCC-+~ -+ NO,- -j- H,O -> zCe+3 -I- NO,- + zH+ 2922-1 4 + 0,-z --z zCe-t3 + O2 2Cc’4 + c,o,-* --z 2ce+3 + ZCO,

zCC-+~ -+ C,Hd(OH), --F 2Cc+3 + C&,0, + zH* 2Ce-b4 + CH,COCOOH + H,O --z zcc”3 + CH&OOH t- CO2 + zH’

In the present investigation the substances have been determined indirectly by a volumetric method using ccric sulphate as oxidizing agent. The excess of standard ccric sulphate added to each of the substances was titrated with standard ferrous cthylenediamine sulphatc solution using ferroin as an indicator.

EXPERIMENTAL

II known wcl&t of each substaucc was mixcd with an CXCCM of standard cctlc sulphate solution and the xnixtatrc acidified with sulphuric acid to keep its normality between I aud zN. In case of potassium thiocyanatc the normality of the mixture with rcspcct to sulphuric acid wns kept between 4 n11d ON. The mlxturcr containing sodium nitrltc, sodium oxalatc, hydroquinonc and pyruvic acid wcrc warmed to nbout Go0 C., and the mixtures containing cuprous chlorldc and potassium tliiocyanatc wcrc heated for about ten minutes and then allowed to cool. In each case the cxccss of ccric sulphatc was titrated against standard ferrous ethyicncdiaminc sulphatc solution using fcrroin as an indicator.

Ccric sulphntc was standardized with ferrous cthylcncdiaminc sulphatc (FES) which was prepared by the method of CARAWAY and OESPER ftoc. cit.).

* KATHRYN P. CARAWAV AND RALPH E. OESPER, J. Ckem. Educ., 24 (1947) 235.

SC)G 1%. SINGW, S. SXNGIX VOL. 14 (1956)

TIE results given in ‘I’xl~lcs I to IX show that thu sul~stancca can lx tlctcrmmctl indirectly 1)~ the vol~~mctr~~ method, using ccric sulphatc as an ox~tl~xing agent In acid medium

-- -..._ _ -_-. . .._c__-- .._- _L _. _. --_._ ...c___ -___-_I __ __ ._._ __--.___.. _ _. _ .-._.. _..._ - _____ .

Fc.W..(Nlt,),SO, MI.0 N/m Cc(S0,). mhlcrl

N/&Y> PBS 1tsrrt tar N/m CcfSO,), tcred by

FCSO, ~Nfi,~&O,.Glf,O lcthcrr CA ccss

Fe.93, (NII,),SO,.(rfl,O ~0wI

CC’SO,), TlZl Id) ( Wl) ( wtl) (id _ . ._ _ -- _. ..-. .-. _-__- _ _. ._“_. -... . _.-. - .._ __-___- ._. _

o.oy)tJo I O.OCl 5.00 5.00 o.ogH I

0.1gHo 20.00 3.90 ,10.10 0.tg81

0.2g50 25.00 9.95 15.05 0.295 I “.3fJ32 30.00 9.95 20.0-j 0.3’132

0,4’)02 40 00 15.00 25.00 0 4903 .- _ ._ _ _ . _ ._.. -_.. . . . _ _. . _. ..-. _ ._ _ _ ._ _... _.._. ._ ._ -___ . _ . . - _____ -..-_.-

CIJI’ltOUS CIlLORl~3iS - .-. -.- ._I. --.---“_.-- ___... _.I_ .-.. -_. _. --

Cll,CI, N/m Ct(SV,), N/m FliS rtsed N/m Ce&WJ,), Cl&l, Iukoi dded /or 6!ICdSS Itred by /owtJ

(a Cr/SI),), C*d&Z*

{t&j (ml) (ttd] (RI .___-.__.__ _.__ - ._c___._. --- __.- _-_ __ _ _.* ___” _..___. _. _- __^ ._._-. __.___* ._ _ ___ . . . . __-_- _- _ ---_ __-- .__

0.0247 LO.00 I fj.00 5.00 O.OZ‘@

0.0494 20.00 ! 0.00 10.00 0.0495 0.0740 2o.oc) 5.00 r5.00 0.07.$2

o.ogkj 30.00 IO.00 20.00 0 ogc)o

0. !I 36 43.ao 20.00 23.00 0.1138

.- ._” - .-. _ _ __- . __ _- _. __ __..... __.. __ ._ . _ _ -._ . _ __--_. _ .(_.- _ ____ - __.-.. - ._ -__- _-__-___ __ __-_ --_._-

r’orhssruhr TfIIOCYANATI~ - ._. .I_ . - _-._ _ __.__ - _.__ __-. - ___._____ _ _ __“_^__ _. ._

N/l” cc(so,), . . ._ . -. _ L__ ------ -- --.-

Njao FI:‘S ltsctl Njm Ce(SO,), XCNS rrrlricrl f&gy rrsed by /oroul

h=CNS (td) (##Ij4 = ftrtll liTI _ __

O.OO‘(O IO.00 5.00 5.00 O.QO.+ 1 a.ooHo ‘Z0.00 Q.90 iO,iO 0.0&Z

0.01 IL 30.00 i5.00 lg.00 O,OIZI

o.otGo 35.00 I fj.00 ‘0.00 0.01G2 0.020 I 40.00 15.00 25.00 0.0202

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

SO01 Uhf ‘1 fIIOSUX.f’ftA-I I.5 _-._ --- -._ __. _-__. - _.-._-. _ -- . . . .._ __ .I _.--_._- ___. -_____. _ _ “-__ - . . . .

Nn,S,0,a511,0 tahwr,

N/PO CC(SO,)~ dlrtl

N[ao FES I trsd /or C\CESJ

Nlm Cc(SO,), tcscd by

lsl (Id) Ce:c(.w,),

{IIll) 4va‘Sp.. 5rr,o

IW (d -___ _ ._._ ____.. _ . _.._. .__-. -_ .-..._ . ..-...-. - _ __.I_ ._-_ L r__...._ - .__ . . . . _ _ __.- ._.-“_-.-.

0.0632 10.00 4.90 5.10 0.0633 0. I%~5 20.00 9.95 10.0s o.rz47 0.17.)0 25.00 10.9.5 I ‘f.O_=J 0. 1744 0.2478 3s.00 1,5.00 20.00 0.2482 0.3098 37.00 12.00 25.00 0.3103

----__----I_-____-_.-“__-_--.-_____.-- _---. __.__ ._.. ---c---.---. ---“.------1___1

VOL. 14 (x956) VOLUMETRIC STUDXES IN OSIDATIOS-REDUCTIOS REACTIONS. VIII 507

SODllJSI SlTRlTE --.- ..--.- --.__ _._.._ -___- --_ _-_ .--- -.-- -_ ---.. -._--__- _------_.- _.__ ._-. -_- _._~_-_---

NaNO, fokrn

0 Of.+0

0.0204

0.0258

0 0327 0.03gG

s/a0 Cr(.w,). arklied

(ml)

1-j 00

20.00

Z.j.00

35 .oo 40.00

0.003s 15 cm

0.0 101 10.00

0.0137 30.00

0.0171 35.00 0.0213 . -15 oo

N/a0 Ce(SU,), nrlded

141 (Ud) _----..- -__.-__-. ._-_-.- .-._. - -.

0.02‘~0 15.00

0 0334 20.00 O.O‘(tj8 30.00 0.0670 35.00

0.0835 ‘)5 .oo

s/m FES nsrd /or CTlCCSS

WSO,), r-ml)

. _-__. _

G.80 H. IO

10.00

16.00

17.00

__ _. .

.v/ao Ce(SO,), NnNO, ~csecl by /0lInd sa so,

(4 (fi) ..- __ -_ _. _ _ _._ _ _ _ ..-__ -

8.20 O.OL.+l

I 1 .r)O 0.020~

15.00 0.0259 19.00 0.0328

L3.00 o 0397

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

I I .oo ‘, . 00 0 003.)

7 .oo I L.IfJ o.oro3

‘3.70 IG30 0.0138

L.).GO 20.40 0.0 L 73 Lc).HO 25.20 0 0214

_ ._ _. _ _ . __ -.

SOD1 UJI OXALATlf -.. . . _ - _ . _. - _._ _ _ ._ . .

Nfm I*‘l:‘S rtsd N/m Cr(SO,), Ior ClCCSS Cdso,),

used by (ctmvrc), (c;tfv;‘),

(#Ill) (WI) (s) _ _ ._. .- _ ._ _. _. _.._ --_ . .- _____..-_ __

7.80 7.20 0.024 1 10.00 10.00 0.0335 15.10 I .).‘)O 0.0490

15.00 .zf~.OO 0.0070

20.05 24*9.5 0 083G

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

o.or3S 10.00 4.95 5.05 0.0139 0.0275 20.00 9.95 10.05 o.or7G 0.04L2 25.00 10.00 15.00 0.04 I3

0.05‘@ 30.00 LO.00 20.00 0.0550 o.oG8G 40.00 15.00 25.00 o.oG88

- -. -__-_- . . . _-I _.___ -- __.__ -.__-.-- ___.___. -_.- _... _____~____._ .- .-__- __...-__ _.. .- _-..

508 13. SINGH, S. SINGH VOL. 14 (1956)

‘1’KBLE IX

I’YRUVIC ACID _ _ __- _._. _.. _. _.. . - .__. - _-._ . ___ -_.-._--_-. _ --- _ _ _.__ _ .- _ . -- __-.. .--..--.

crl.c0C0011 N/o0 Ce(S0,], N/go I*‘l;S wccl Nlm GelSO,), CIr,COCOON Iukor dlIC<l /or cxccls trsul by /ound

CclSO,), cII,cOCooIf tc:) (ml) (*d (d) (6) ._.- .__._. . _.___. . _-^ .^.. . t .- .___ . ._- ._... _ . . . _ .

o.orog 10.00 5.00 5.00 0.01 IO

0.02 I8 20.00 10.00 10.00 0.0220

0.0327 30.00 15.05 ‘4.95 0.0329 0.0440 3.5 *oo 1g.00 20.00 0.0440

0.0528 45.00 21 00 24.00 0.0528

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

Ccric .slIlpliatc II:L~ Ixcn iIsct1 iLY an oxiclizlng agent in acltl mctllrlm for tlic intlircct volunictric tlctcr1llini~t1C~nS of fcrrws :unnionium srIllJhatc. cuproIIh cliloritlc, pot;wsilIIn tliiocyanatc, socliurn

tliiowll~li;itc, h~Jt~llllll llitritc, hydrCJ~cI7 prOXit\C, sodium cncalntc, Iiytlrocluinonc irnd pyruvic

witl. ‘l’lu: cxccss of ccric ~ulpliatc, * arltlctl to c:rcli of tlic S~IlJ~taIiccr In ac~tl nm2c11r111~ wiis titrntcd

with stiiIitl;wcl frrrou~ c~tlIylcnctliirt1~iIlc ~IIlpliatc: solution rISiIIg IcrroIn ah aI1 inclicator.

1.x sulfate tic cbrium(lV) lxxt cX.rc utilik comma: cxytlant, cn milieu :rcitlc, poiir Ic dosage

volumbtrrcluc intlircct tlti siilfatc tic fCr(l1) ct cl’;~mmoni~Im, cl11 Clilor~irc tic CuIvrc(l), cl11 tliiocy-

xiiatc tic ptassili iii, tlu tliiosulfatc tic sotlirirn, du IiItritc ilc sodium, rlu licwkydc tl’liyclro&Ic,

rlc I’O%ElliLtC tic SocliIin~, tic l’l~yclrocluinonc ct tic l’acitlc pyruviquc. I,‘cxcb clc hulf;ltc clc cCriiiin(IV) njoiltc’: ?r cli;icunc tic ccs ~ubstanccs, cl1 milieu iLCidC. cst titrb xvcc llnc trolution clc SUlfiltC de

fcr(ll) CC d’~tl~yltnccli~~ininc. on prbscncc tic fcrrolnc comtiic inclicatc~ir.

Ccr(IV)sulfat wurclc in saurcm hlctliunl nix Oxytlatlonsmittcl fiir tlic lntlilcktcn volumetrischcn Ucstininiiingcn von Arilrnorlilinilrirc~siilfat, 1Clll~fCr(l)Cllloritl, ICi~llurntlliocy;ulnt, Natriurn- thiosulfat, Natriumnltrit, Wasscrrtoffpcroxytl, Nntriumoxalnt, 1 lytlrocliinon rind Hrcnstran- bcns:iurc vcrwcntlct. l>cr CJl~crscliuss an Ccr( LV)s~~lfat, clcr jctlcr dcr olxn nufK:cfiilirtcn Substanzcn in saurcm Mcclium ziigcsdzt wiirclc, liisst sich mit cingcstclltcr Eiscn( II jhtlrylci~dinm~nsi~lf~it- IClsiing xnriicktitricrcn. l~crroin client Clill)Ci als Inrliltntor.

l<ccc~vctl Octolxr roth, 1955