The hydrogen-ion dependence of the reaction of chromium(II) with vanadium(III) in aqueous perchloric acid solutions

Abstract

A further study has been made of the reaction of chromium(II) with vanadium(III) in aqueous perchloric acid solution, µ= 0·5M, at 25°. As already reported, the reaction is of first order with respect to both reactants: d[Cr^III]/dt=k_obs[Cr^II][V^III]. Details of the hydrogen-ion dependence for k_obs are of interest because they provide information regarding the mechanism of the reaction. Over an extended range of hydrogen-ion concentrations down to 0·0157N, the hydrogen-ion dependence is of the form k_obs=al(c+[H⁺]). Although the limiting value of a/c has not been reached there is no evidence for the more complex hydrogen-ion dependence k_obs=(a+b[H⁺]^–1)/(c+[H⁺]). Values of a and c are 0·50 and 0·10, respectively, and an upper limit for b is 0·002.