THERMODYNAMIC TRANSFER PROPERTIES FOR NA-ACETONITRILE MIXTURES(, TL+ AND AG+ TO WATER)

Gibbs energies of transfer for Na+, for Tl+ and for Ag+ from acetonitr ile to its mixtures with water have been obtained from electrochemical measurements employing the bis(biphenyl)chromium assumption. Entropie s of transfer were calculated from the temperature coefficients of ele ctrode potentials and from half-wave potentials on the basis of the as sumption of a negligible thermal diffusion potential. Enthalpies of tr ansfer were derived from Gibbs energies and entropies of transfer. Pre ferential solvation between the soft acceptor, Ag+, and the soft donor , acetonitrile, was observed, whereas the hard Na+, and also Tl+ inter acted more strongly with water. The changes for the Gibbs energies of transfer in the solvent mixtures could be accounted for as donor-accep tor (coordinative) interactions between cations and solvent molecules taking into account the principle of hard and soft acids and bases. Ch anges in the entropies of transfer are discussed on the basis of inter actions between entities consisting of the cations with their first so lvation shells and the surrounding solvent matrices.