Kinetics and mechanism of the silver(I) catalyzed oxidation of water with peroxodiphosphate in acetate buffers

A kinetic study of the title reaction (i) was made by estimating peroxodiphosphate (pdp) iodometrically, K4P2O8+ H2O [graphic omitted] 2 K2HPO4+ 0.5 O2(i) Two species of pdp, H2P2O82– and HP2O83–, and two species of AgI, Ag+ and Ag(O2CMe), participate in the reaction. The rate law (ii) holds, where K3 is the acid dissociation constant of –d[pdp]//dt=(k3[H+]+K3k4+k3′K[H+][–O2CMe]+k4′KK3[–O2CMe])[AgI][pdp]//(K3+[H–])(1 +K[–O2CMe])(ii) H2P2O82– and K the complex formation constant of Ag(O2CMe). The values of k3, k3′, k4, and k4′, are 0.04, 0.0935, 0.19, and 0.42 dm3 mole–1 s–1 respectively at 50 °C and I= 1.0 mol dm–3. A comparison of this reaction with that of S2O82– with AgI is made.