Temperature coefficients of Cu|Cu2+ and Hg|Hg2+ electrode potentials and Gibbs energies, entropies and enthalpies of transfer for Cu2+ and Hg2+

Abstract

Temperature coefficients of the electrode potentials for the Cu|Cu²⁺ and Hg|Hg²⁺ couples have been derived from potentiometric measurements at different temperatures vs. the Ag|Ag⁺(0.01 mol dm^–3, 25 °C) reference electrode in water, acetonitrile, benzonitrile, propylene carbonate, ethane-1,2-diol (ethylene glycol), acetone, N-methylacetamide, N,N-dimethylformamide, N,N-dimethylacetamide, methanol, ethanol, propan-1-ol, nitromethane, sulfolane (tetrahydrothiophene-1,1-dioxide), dimethyl sulfoxide and N-methyl-2-pyrrolidone. The temperature coefficients for the Cu|Cu²⁺ system in acetonitrile and benzonitrile were calculated from the temperature coefficients of the Cu|Cu⁺ and Cu⁺|Cu²⁺ couples. Single-ion entropies of transfer of Cu²⁺ and Hg²⁺ from N,N-dimethylformamide as reference solvent were calculated from the temperature coefficients of the Cu|Cu²⁺ and Hg|Hg²⁺ electrode potentials. Gibbs energies of transfer were derived from the electrode potentials of the Cu|Cu²⁺ and Hg|Hg²⁺ couples measured at 25 °C against the Ag|Ag⁺(0.01 mol dm^–3, acetonitrile) reference electrode. Transfer enthalpies were calculated from the Gibbs energies and the entropies of transfer.