The peroxodisulphate–iodide reaction. Reactivity and ionic association and solvation in isodielectric water–solvent mixtures

Abstract

The association constants of the potassium peroxodisulphate ion pair (KS₂O₈^–) and the reaction rate between peroxodisulphate and iodide ions have been measured in several isodielectric water–solvent mixtures. The sequence of the rate constants does not follow that of the association constants, but agrees qualitatively with the sequences of transition-state solvation energies calculated from excess free energies of mixing. This fact suggests the influence of solvent structure on the reactivity.