SOLVATION THERMODYNAMIC FUNCTIONS IN THE MEAN SPHERICAL APPROXIMATION - BEHAVIOR NEAR THE SOLVENT CRITICAL REGION

Explicit expressions of the mean spherical approximation (MSA) solvation thermodynamic functions, the Gibbs free energy, energy, enthalpy, entropy, apparent molar heat capacities, and partial molar volume are derived starting from the Helmholtz free energy. The thermodynamic consistency of the MSA solvation thermodynamic functions are discussed. The limiting behavior of the MSA solvation thermodynamic functions is compared to the Born theory. The effect of the solvent structure on the Gibbs and the Helmholtz free energy in the MSA is discussed. The results for alkali and halide ions in water are compared with experimental data. The apparent molar heat capacities at constant volume and pressure, and the partial molar volume are calculated along an isobaric line to the critical region of a dipolar liquid. Some recent experiments on solvation thermodynamics in the critical region are discussed. © 1995 American Institute of Physics.