An analytical and kinetic study of the bromate oxidation of vanadium (IV) in acid medium

Abstract

A kinetic and analytical study of the reaction of vanadium(IV) with potassium bromate is reported. The kinetics were studied in perchloric acid media and the reaction was found to obey the rate equation [graphic omitted]. A value for k₀ of 7·50 minute^–1 was obtained at 20° C and an ionic strength of 0·10 M. Values for K₁ of 88·8 lmole^–1 and for the activation energy of 19 kcal. mole^–1 were obtained, and a possible mechanism is proposed for the reaction.

The determination of vanadium(IV) by photometric titration with potassium bromate is feasible at concentrations of vanadium(IV) down to 2 × 10^–3M and at sulphuric acid concentrations above 0·06 M. An accuracy of ±0·5 per cent. is obtained for concentrations of vanadium(IV) between 5 and 10 × 10^–3M. Under these acid conditions bromate acts as a five electron oxidant and bromine is a primary product of the reaction.