Electrode kinetics and double-layer structure : The Zn2+/Zn(Hg) electrode reaction in mixed potassium halide solutions

Abstract

The Zn2+/Zn(Hg) electrode in binary 1 M potassium halide solutions has been studied using the oscilloscopic method for the determination of the kinetic parameters. The apparent standard heterogeneous rate constant, ksh, is found to be a non-linear function of the mole fraction, x, of the components of the base electrolyte. Taking into account the Frumkin correction and the occurrence of complex formation, the measured ksh-values in (1−x) M KCl+x M KI are compared with the amount of specific adsorbed anions, q1. A linear relation is found between log ksh and q1 (Fig. 8), from which it is inferred that the energy of activation decreases linearly with q1. This model is preferred to the assumption of complex reactants.