Standard potentials of silver/silver halide electrodes and ion solvation in glycerol + water mixtures at 25°C

Abstract

Standard e.m.f. of the cells H₂/HX/AgX—Ag (X = Cl, Br, or I) in 10, 20, 30, 40, 50 and 70 %(w/w) glycerol + water mixtures at 25°C are reported. Consideration of the molar free energies of transfer of the proton and halide ions from water to the mixed solvents leads to the view that glycerol is more “basic” than water. The solvation effect opposes but predominates over the electrostatic effect in the transfer of the proton to the mixed solvents. In the transfer of anions, the solvation effect reinforces the electrostatic effect resulting in large positive values of the transfer free energy.