SOLUBILITY OF NONPOLAR GASES IN CONCENTRATED ELECTROLYTE SOLUTIONS

A theory of the solubility of gases in electrolytic solutions is presented which is based on the scaled particle theory. The resulting equation for the solute activity coefficient is compared with experimental data for seven nonpolar gases dissolved in potassium hydroxide solutions over a wide range of electrolyte concentration and temperature. The salting-out effect is well predicted by the theory. Calculated heats of solution agree well with experiment for small solute molecules, but are larger than observed values for the larger molecules. This is attributed to a temperature dependence of the molecular hard core diameter. The proposed theory is superior to electrostatic theories in its description of both the concentration and temperature dependence of the solute activity coefficients for these systems. It is found that the salting-out effect is largely due to changes in the cavity work term, which can be calculated with reasonable confidence. Such changes arise primarily from nonpolar solute-ion interactions, and not from the ionic charges themselves.