Evaluation of the rate parameters from i-E polarographic characteristics—kinetic study of oxidation of the Mo(V)—EDTA complex by vanadyl chelate

The kinetics of the oxidation of Mo(V)—EDTA by vanadyl chelate has been studied by the catalytic current technique of dc polarography. The reaction order appears to be first order in both chelates and EDTA. The kinetic analysis of the current-potential curves combined with the current ratio technique has been successfully applied to interpretation of the data obtained from polarographic measurements. Agreement between theory and experiment obtained is quite satisfactory as regards the effect of the following catalytic reaction in the polarographic wave. The rate constant for oxidation of the Mo(V) chelate is log k=4.30±0.02 obtained by the catalytic to non-catalytic current ratio method, and log k=4.45±0.07 obtained from the half-wave potential shifts at t^o=25.0±0.1°C. The mechanism of the electrochemical reaction considered is also discussed.