Rates of fast reactions between ions in solution

Abstract

The Smoluchowski-Debye method of computing maximum rates of reactions in solution is examined for second-order reactions between ions of equal valency. It is shown that when reactive ions contribute to the ionic atmospheres of their reaction partners, the method is inconsistent unless the two reactants are present in equal concentrations. This result throws some doubt on the validity of the method even when these concentrations are equal. It is shown also that whenever the ionic atmospheres of the reacting ions are perturbed (depleted) by the reaction, the maximum rate is enhanced as compared with the corresponding unperturbed rate. The magnitude of this correction is computed for small perturbations.