Abstract

The kinetics and mechanism of the reduction of potassium trisoxalatoferrate (III) by thiophenol was investigated spectrophotometrically in aqueous hydrochloric acid medium at [H+] = 0.2 mol dm-3, I = 0.6 mol dm-3 (NaCl), 29 ± 0.1ºC and 420 nm. Spectrophotometric titration following the mole ratio method gave a point of inflexion at the mole ratio of 1:1, inferring that one mole of the oxidant consumed one mole of the reductant. Kinetic decays indicated first order dependence of the reaction on both oxidant and reductant which gave an overall order of second order. Reaction rates increased with increase in [H+] but decreased as ionic strength was increased. Increase in the concentration of added ions had positive effect on the reaction rate and free radicals probably did not participate in the reaction. The reaction was rationalized in terms of the outer-sphere pathway.