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Consideration of some dilute-solution phenomena based on an expression for the gibbs free energy/sup 1/

Conference · · Int. J. Thermophys.; (United States)
OSTI ID:6909773
Rigorous expressions based on the Lennard-Jones (6-12) potential, are presented for the Gibbs and Helmholtz free energy of a dilute mixture. These expressions give the free energy of the mixture in terms of the thermodynamic properties of the pure solvent, thereby providing a convenient means of correlating dilute mixture behavior with that of the pure solvent. Expressions for the following dilute binary solution properties are derived: Henry's constant, limiting activity coefficients with their derivatives, solid solubilities in supercritical gases, and mixed second virial coefficients. The Henry's constant expression suggests a linear temperature dependence; application to solubility data for various gases in methane and water shows a good agreement between theory and experiment. In the thermodynamic modeling of supercritical fluid extraction, we have demonstrated how to predict new solubility-pressure isotherms from a given isotherm, with encouraging results. The mixed second virial coefficient expression has also been applied to experimental data; the agreement with theory is good.
Research Organization:
National Bureau of Standards, Gaithersburg, MD
OSTI ID:
6909773
Report Number(s):
CONF-850617-
Conference Information:
Journal Name: Int. J. Thermophys.; (United States) Journal Volume: 7:4
Country of Publication:
United States
Language:
English