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

Abstract

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, H₂P₂O₈^2– and HP₂O₈^3–, and two species of Ag^I, 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])[Ag^I][pdp]//_{(K3+[H^–])(1 +K[^–O2CMe])}(ii) H₂P₂O₈^2– and K the complex formation constant of Ag(O₂CMe). The values of k₃, k_3′, k₄, and k_4′, 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 S₂O₈^2– with Ag^I is made.