Kinetics of oxidation of uranium(IV) by permanganate ion in aqueous perchlorate media

Abstract

The kinetics of oxidation of uranium(IV) by permanganate ion in 1.0 mol dm^–3 perchloric acid solution has been investigated using a stopped-flow spectrophotometer. The reaction was found to be second order overall and first order in the concentrations of both reactants. The catalytic effect of the perchlorates of Hg²⁺, Cu²⁺, and Fe³⁺ on the reaction rate has been investigated. The activation parameters were evaluated and found to be ΔS^‡= 30.52 ± 1.22 J K^–1 mol^–1, ΔH^‡= 62.89 ± 1.87 kJ mol^–1, and ΔG^‡= 53.79 ± 1.44 kJ mol^–1. A tentative mechanism consistent with the kinetics is discussed.