Activation parameters for the peroxodisulphate + iodide reaction in several water + cosolvent mixtures

Abstract

The rate of the reaction between peroxodisulphate and iodide ions has been determined in methanol, t-butyl alcohol, glycerol, acetonitrile and sucrose + water solvent mixtures. The reaction rates have been measured at different temperatures in several cosolvent + water mixtures which were isodielectric at 25 °C. Correlation of these reaction rates with solvent parameters has been attempted. Plots of activation enthalpies and entropies against solvent composition show extrema giving a gradual change in Gibbs activation free energy. These results are consistent with currently accepted theories of the effects of organic solvent on the structure of water.