Measurement of homogeneous reaction rate by concentration-step, controlled potential electrolysis

Abstract

A concentration-step method was introduced to controlled potential coulometry for the study of chemical kinetics and was named concentration-step, controlled potential electrolysis. In this method, an amount of the reaction agent is added to the electrolytic solution which is maintained in a controlled potential condition and the current-time curve is measured. The current-time curve has a peak and the reaction rate is obtained by measuring the time when the current is maximum. To demonstrate the present method the reactions of ethylenediaminetetraacetato-ferrous complex and several oxidizing agents were studied and the pseudo first-order reaction rate constants were evaluated. The optimum range of the measurement was estimated to be 10 −3–10 2 dm 3 mol −1 s −1 and the rate constant of the reaction of potassium bromate and ethylenediaminetetraacetato-ferrous by this method was in fair agreement with that found by polarography.