Determination of osmotic and activity coefficients in mixed electrolyte systems. Systems containing clathrate-forming salts

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There is a paucity of thermodynamic data on mixed electrolyte systems containing clathrate-forming compounds covering the entire ionic strength fraction range. Using an isopiestic vapor pressure apparatus, we have determined osmotic coefficients for aqueous solutions containing sodium chloride and the clathrate-forming salt tetra-n-butylammonium chloride over a wide range of total ionic strength and ionic strength fraction at 25°C. We have used the Scatchard-Rush equations to fit the osmotic coefficient data for solutions of each pure component and the mixtures. From these equations we calculated the excess free energy of mixing and the activity coefficients of each solute component as a function of ionic strength fraction and total ionic strength. Friedman's interaction parameters, g0 and g1, are calculated and the results discussed. © 1984 American Chemical Society.

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Journal of Physical Chemistry