Gas-Liquid Solubility Measurements

The dissolution of a gas in a liquid is basically a two-stage process. First a cavity must be formed within the solvent of sufficient size to accommodate the solute molecule, and this step is followed by the insertion of the solute within the solvent cavity with a resultant change in the energy of the system which depends primarily on the magnitude of the solvent-solute interactions. This second stage of the process is now reasonably well understood in terms of the statistical mechanical theories of fluid mixtures discussed briefly in previous sections, although accurate predictions of thermodynamic excess functions are only possible in a limited number of cases when auxiliary measurements enable explicit values of and x to be estimated. It is, as yet, not possible to predict gas solubilities with comparable confidence. 

Hildebrand and his co-workers have produced accurate gas solubilities for a great variety of systems over a lengthy period, and many of their measurements are tabulated in the comprehensive review of Battino and Clever. They have, however, persisted in the use of solubility parameter theory to correlate and interpret their measurements and in much of this work systems containing fluorocarbons either as the gaseous solute or as the liquid solvent appear to behave anomalously when compared with most other mixtures composed of non-polar molecules. 

When a comparison is made between fluorocarbons and hydrocarbons containing equal numbers of carbon atoms, it is found that, under the same 

Hanna and J. L. Lippert, Molecular Complexes , Paul Elek, London, 1973, Vol. 1, p. 1. 

The high solubility of many gases, including oxygen, in fluorocarbons has led to these compounds being used as blood substitutes in cardiopulmonary machines and as potential carriers in liquid breathing. Tham et have recently measured the solubility of O2, N2, and CO2 in the three commercially available fluoro-ethers perfluoro-l,4-di-isopropoxybutane, perfluoro-1-isopropoxyhexane, and perfluorobutyl-perfluorotetrahydrofuran and noted 

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