The thermodynamic properties of electrolyte solutions: Some formal results
Abstract
The Kirkwood–Buff approach is used to obtain exact determinate expressions for the thermodynamic properties of electrolyte solutions. The solvent is treated at a molecular level and the thermodynamic functions are expressed in terms of ion–ion, ion–solvent, and solvent–solvent correlation functions. The equations obtained are particularly useful when used in conjunction with integral equation theories. The low concentration limiting behavior of the microscopic expressions is examined and it is shown that the Debye–Hückel limiting law for the activity coefficient can be readily extracted from the molecular theory. Also the partial molecular volume of the salt is considered in some detail and microscopic relationships are given for the infinite dilution value.