Studies in ion solvation in non-aqueous solvents and their aqueous mixtures. Part 15.—Free energies of transfer of cadmium chloride from water to 10–40%(w/w) methanol-water mixtures at 25°C; dissociation of CdCl+; use of dilute cadmium amalgam electrodes. The group II cations.

Abstract

The cell Cd(Hg)∣ CdCl₂∣ AgCl—Ag has been used to obtain the standard molar free energies of transfer, ΔG^°_t, of cadmium chloride from water to 10%, 20% and 40%(w/w) methanol-water mixtures. Cadmium chloride is a weak electrolyte. This was allowed for in computing the standard e.m.f. values of the cell; dissociation constants of CdCl⁺ were also determined. The behaviour of the Group II cations, Cd²⁺, Zn²⁺, Sr²⁺ and Ba²⁺, in the methanol-water system is discussed in terms of the “acid-base” theory and their “hardness” or “softness” as Lewis acids, and they are briefly compared with the univalent cations of Group I.