Thermodynamic parameters for dissolved gases.

In 1958 and subsequently we correlated properties of solutions of gases in liquids by using the "force constants," epsilon/k, and collision diameters, sigma, which serve as parameters in equations for molecular pair potential energy such as that of Lennard-Jones or its variants. Unfortunately, however, the figures for these parameters that have been published are so scattered for the same gas as to make it difficult to select "best" values; in 1967, therefore, I substituted for these indirectly determined molecular parameters the directly and accurately known molal energy of vaporization, DeltaE(b) (v), and the molal volume, v(b), of the liquefied gas, both at its boiling point. A plot of values of DeltaE(2) (v) against the most trustworthy values of epsilon/k reveals direct proportionality. The same is true for V(b) (1/3) versus sigma.Recent examples will be shown of excellent linear correlations with these parameters of thermodynamic properties of different gases in the same solvent.It is no less "scientific" and far more practical to regard molecules of a solute as immersed in the potential energy field of its solvent than it is to split this field into imperfectly known pair potentials of questionable additivity and to try to integrate them over an undetermined distribution function.