Single-ion transfer properties: a measure of ion-solvation in solvents and solvent mixtures

Abstract

Single-ion transfer properties such as Gibbs energies, entropies and enthalpies may be successfully employed to account for the interactions of ions with solvents. Several electrochemical methods such as polarography or potentiometry in combination with extrathermodynamic assumptions, e.g. the assumption of a reference redox system, the assumption of a negligible liquid junction potential or the assumption of a negligible thermal diffusion potential permit the estimation of single-ion transfer properties. These data are a basis for the understanding of the interactions of ions with solvents and solvent mixtures. Gibbs energies of transfer may be used to learn about the nature of the chemical bond between ions and solvent molecules and to quantize the donor and the acceptor properties of solvents. Entropies of transfer ( TΔ t S 0-values) yield information of the effects of the solvated ions on the surrounding solvent matrix. The contributions from the Gibbs energies and the TΔ t S 0-values allow to perceive the enthalpies of transfer. Single-ion transfer properties into solvent mixtures show the effects of preferential solvation.