Studies in ion solvation in non-aqueous solvents and their aqueous mixtures. Part V. The halogen acids in 10, 20, 40, and 60%(W/W) acetic acid–water mixtures at 25°

Abstract

Standard e.m.f.s. have been obtained for the cells H₂|HX|AgX–Ag (X = Br or I) in 10, 20, 40, and 60%(W/W) solutions of acetic acid in water. Some measurements were made by a new rapid technique. Molar free energies of transfer, ΔG_t°, from water to the mixtures, of HCl, HBr, and Hl, have been calculated. These have been split into contributions from the ion constituents by the method described earlier in this Series. The proton is in higher free-energy states in the mixtures than in comparable methanol– or dioxan–water mixtures and, probably, than in pure water. The anions are in lower free-energy states in the mixtures than in the methanol– and dioxan–water mixtures, though not than in water. These findings are generally in accord with the theory of ion solvation developed earlier.