A kinetic study of the redox reaction of indigo carmine by nitrite ion in aqueous hydrochloric acid medium

Author(s): J.N.Edokpayi*, J.F.Iyun, S.O.Idris

The kinetics of oxidation of indigo carmine (hereafter referred to as IC) by nitrite ions have been studied in aqueous hydrochloric acid under the pseudo – first order condition of excess [NO2 -] at 27 ± 1C, [H+] = 510-2 mol dm-3 and ionic strength I = 0.5 mol dm-3. The stoichiometry of the reaction was observed to be 1:1 mole ratio of IC to nitrite ions. The reaction is first order with respect to both the [IC] and [NO2 -]. The overall reaction conforms to the rate law –d[IC]/dt = a [NO2 -] [IC] [H+]0.39, (a = 1.3010-2 dm6mol–2 s–1.).

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