Electrode kinetics by analysis of polarographic current-time curves

Abstract

The method, which enables the evaluation of the kinetic parameters of electrode reactions by analysing the polarographic current-time curve, is presented. As examples of the application of this method, the electrode reactions of the simple zinc ions and of the zinc-acetate complex ions were experimentally examined. For the former case the current-time curves were measured as a function of the electrode potential and the perchlorate concentration. It was found that the standard rate constant, corrected both for the increase of the activity coefficient of the zinc ion and for the Frumkin double-layer effect, has a constant value over the concentration range of perchlorate 0.6–4.0 M. For the latter case the current-time curves in the solution with constant ionic strength (4 M) are measured as a function of the electrode potential and of the acetate concentration. It was concluded that the potential-determining reaction of zinc-acetate complexes is referred only to the species Zn(Ac)2 over a range of acetate concentrations larger than 0.5 M.