Use of Hildebrand and Lamoreaux's theory to predict solubility and related properties of gas-liquid systems

There is a need in many fields such as chemical engineering, process chemistry and pharmacology for reliable data on the solubility, entropy of solution and partial molar volume of gases in liquids. Experimental data are not available for many systems of practical and academic importance and consequently a reliable theory to predict values for these properties would be of great use. Recent refinements of solubility parameter theory have been successful in predicting such values for several systems and in this paper results obtained from this theory are compared with experimental measurements on a large range of gas-liquid systems. The agreement found is satisfactory in the most part, but for helium, neon, xenon, hydrogen and deuterium, the predicted results deviate consistently from the experimental values. This is to be expected on the basis of some of the earlier results of solubility parameter theory and an empirical modification is proposed that yields significant improvements in the predicted values. This has also been used to predict values for carbon dioxide, tetrafluoromethane and sulphur hexafluoride to which the theory is not directly applicable. Values predicted by solubility parameter theory are compared with those obtained by Battino and co-workers from scaled particle theory. In general, the two theories are equally successful in predicting solubilities, but refined solubility parameter theory yields better values of entropy of solution. It is concluded that the theory provides a useful means of predicting solubility and entropy of solution but that prediction of partial molar volume results is limited because of the paucity of data for the thermal pressure coefficients of the solvents. Attention is drawn to apparent inaccuracies in certain experimental measurements. The interrelationship between the various forms of the entropy of solution used by different workers is clarified. A value of the energy of vaporisation of carbon dioxide, δE2v=2.64±0.15 kcal/mol is calculated.