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Kinetics and mechanism of the electron transfer reaction between tetraoxoiodate(VII) ion and indigo carmine in aqueous hydrochloric acid medium

J. N. Edokpayi. J. F. Iyun and S. O. Idris

The stoichiometry, kinetics and mechanism of the electron transfer reaction between tetraoxoiodate(VII) ion and indigo carmine (IC) have been investigated at 27 ± 1 oC. The rate of the reaction is: [ ] [ ]. 1 [ ] [ ] ( 4 3 6 3 4 IO IC K H k K H Rate k t - + +               + = + The rate of the reaction is independent of changes in ionic strength of the reaction medium in the range of 0.1 ≤ I ≤ 0.8 mol dm-3. Added cations catalyzed the reaction whereas added anions inhibited the rate of the reaction On the basis of the result obtained the outersphere mechanistic pathway is proposed for this reaction. Key words: Tetraoxoiodate(VII) ion, Indigo carmine, Mechanism, Kinetics, Ionic strength.