A general model for the solubilities of gases in liquids

The solubility of a compound is one of its most important properties. Here, regression relationships are presented for solubilities of a series of gases in water and in four organic solvents, treating each solvent separately. The solubilities are related to the Coulombic intermolecular interactions arising from the intrinsic polarities of the solute molecules and the polarities induced in them by the solvent. As a measure of intrinsic polarity, a statistical quantity defined in terms of the solute’s molecular electrostatic potential is used, and the measure of induced polarity is taken to be the solute’s molecular polarizability. Regression analyses show that solubility in water is best expressed in terms of just the intrinsic polarities of the solutes, but for the organic solvents, it is necessary to take into account both the intrinsic and the induced polarities of the solutes. If the dielectric constant of the solvent is included in the regression analysis, then a single relationship can encompass all four organic solvents. Solute molecular volumes were not found to contribute significantly to the present relationships.