Dissociation equilibria in pyrophosphates and kinetics of degradation. Part 2.—Kinetic studies

Abstract

A kinetic study has been made of the degradation of pyrophosphates in the concentration range 10^–4–10^–1M and at temperatures 50, 60, 65 and 70°C. The pH was maintained at a value between 1.25 and 6.85 and the ionic strength from 0.301 to 1.14. The reaction is first order in total pyrophosphate concentration. The H⁺ ion acts as a catalyst and also controls the equilibria between various pyrophosphate species. The overall rate constants are resolved into individual rate constants, using values of the dissociation constants of pyrophosphoric acid which had been determined under the conditions of the kinetic experiments. Activation parameters for the overall reaction, as also for the step reactions, have been calculated.