Activation Parameters of the Eu3+/Eu2+ Electrode Reaction in Mixed Solvents

Abstract

Summary The rate constants for the electrochemical reduction of Eu3+ in water–acetone and water–dimethylformamide solvent mixtures with different parts of the organic component were measured in the temperature range 15°C–40°C. The activation parameters for this reaction were evaluated. While the activation enthalpy does not depend on the composition of the solvent, the activation entropy changes follows the changes of reaction rates. The entropy contribution (responsible for the form of dependence of rate constants on the composition of the solvent) is obviously related to structure changes of the resolvatated particle.