Inversion of the Kirkwood-Buff theory of solutions: Application to the water-ethanol system

A general procedure is outlined whereby experimental data such as partial molar volumes, isothermal compressibilities, and partial vapor pressures may be processed to obtain information on the extent of the affinity between two species in a mixture of two (or more) components. A particular example of the water-ethanol system is processed in this manner to obtain the quantities G _αβ which are integrals over the pair correlation functions between two species α and β. This information is relevant to several topics of interest in the field of aqueous solutions, such as the solvation of solutes, hydrophobic interactions, and structural changes in the solvent brought by the addition of solutes to water. More generally it may be used to characterize the properties of various mixtures on a molecular level.