Kinetic salt effects on the reactions of hydrated electrons produced photochemically from ferrocyanide ions

Abstract

When applied to a reaction between ions occurring in the vicinity of a highly charged ion, the theory developed in the previous paper predicts much larger kinetic salt effects than were suggested by the activity coefficient method. This disagreement seems to be due, essentially, to an error in calculating activity coefficients of ions with a non-equilibrium environment. A comparison of theoretical predictions with the experimental results of Airey and Dainton showing high salt effects for hydrated electrons produced photochemically from ferrocyanide ions indicates a discrepancy of two orders of magnitude between the experimental conditions and those where such behaviour is expected. An explanation is that the hydrated electron may undergo reaction nearer to the parent ion than one would calculate from the solute concentrations and rate constants if the dissociation of the photoexcited ferrocyanide ion is influenced by the proximity of an acceptor.