Kinetics of the Oxidative Silver Chloride Formation on Silver with CoIII(NH3)5Cl3 Studied by Galvanostatic Reduction of the Chemically Formed Silver Halide

Silver chloride was formed on a rotating silver disc electrode by oxidation with [CoIII(NH3)5Cl]2+ in acid solution and subsequently reduced galvanostatically in order to determine quantitatively the amount of silver(I) formed during the chemical oxidation. By varying both the oxidation time and the concentration of the cobalt complex as well as that of chloride the kinetics of the formation of silver chloride was studied indirectly. As long as the concentration of chloride exceeds that of the cobalt(III) complex the reaction is first order in [CoIII(NH3)5Cl]2+ and almost zero order in Cl−. The diffusion controlled process can be explained with the theory of mixture potential and mixture current and may therefore be regarded as a corrosion process.