Thermodynamics of associated solutions: Henry's constants for nonpolar solutes in water

Hu, Y., Azevedo, D., Lüdecke, D. and Prausnitz, J., 1984. Thermodynamics of associated solutions: Henry's constants for nonpolar solutes in water. Fluid Phase Equilibria,17: 303–321.A systematic derivation is presented for the Helmholtz energy of a van der Waals fluid mixture whose nonideality is ascribed to both chemical and physical interactions; this derivation, applicable to all fluid densities, leads to an equation of state which contains chemical equilibrium constants in addition to the customary physical van der Waals constants a and b. Attention is given to the need for simplifying assumptions and to the variety of symplifying assumptions that can lead to useful results. A particular equation of state is used to correlate Henry's constants for nonpolar solutes in water over a wide temperature range. The correlation, however, is only partly successful, because a one-fluid van der Waals theory of mixtures is not satisfactory for mixtures containing molecules that differ appreciably in size, especially in the dilute region.