Abstract
The kinetics of oxidation of the ternary complex of cobalt(H) involving nitrilotriacetate and glycine by peroxydisulphate was studied kinetically in aqueous solution over a range of temperatures, pH, ionic strength, different concentrations of complex and oxidant. The oxidation rate increases with decreasing pH. The reaction was catalysed by Ag+ through the formation of Ag2+ which is very strong oxidising agent. The rate of oxidation was derived and compared with the experimental rate law which is consistent with the proposed mechanism. Zero order condition was maintained in all runs by the presence of a large excess of S2O82- (>10-fold) and the rate of reaction obeys the following equation:
rate = (K1K2K5[H+] + K3K6)[Ag+][S2O82-].
Thermodynamic activation parameters were calculated. It is proposed that electron transfer proceeds through an outer-sphere mechanism. The prepared complex was characterised by physicochemical and spectroscopic methods.