Kirkwood-Buff theory of solutions. An alternative derivation of part of it and some applications

Abstract

An alternative derivation of part of the Kirkwood-Buff theory of solutions, which uses essentially classical thermodynamic concepts is presented. This theory relates the thermodynamic properties of a solution to the integrals of the radial distribution functions of the various molecular pairs present. Useful expressions are derived for electrolyte solutions and for solutions of two and three components. Of particular importance are the general expression for the primary medium effect for a neutral electrolyte and the expression for the effect of one component on the solubility of another in a three component system, which shows how the theory can be used as a general basis for discussing hydrotropy and related phenomena.