Absolute electrode potentials in dioxane-water solvent mixtures and transfer free energies of individual ions

Abstract

Standard e.m.f. values at 25 ° C for the cells Pt, H 2(g, 1 atm) ¦HI, solvent ¦AgI, Ag and M, Mx ¦solvent ¦AgX, Ag in nine solvent mixtures of dioxane with water, containing up to 80 wt.% dioxane, are reported. The e.m.f. data were used to determine standard absolute potentials of the hydrogen, the Ag, AgX (X  Cl, Br and I) and the M, M + (M  Li, Na, K, Rb and Cs) electrodes in these solvents by a new method reported recently. The radii of the solvated cations and their solvation extent in such media have been evaluated. The standard Gibbs free energies of transfer of individual ions from water to the respective solvents have also been computed. The results are interpreted and discussed in terms of the solvation characteristics of the solvents. The data obtained in the dioxane-water solvent system are compared with those in various aqueous protic and aprotic solvent systems.