Statistical mechanics and thermodynamic properties of liquid multicomponent mixtures. Part I. The Taylor series for quasichemical equilibrium of ternary mixtures

• Published in: Fluid phase equilibria Vol. 12; no. 3; pp. 201 - 216
• Main Authors: Mickeleit, Michael, Lacmann, Rolf
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 1983
• ISSN: 0378-3812; 1879-0224
• DOI: 10.1016/0378-3812(83)80062-4

Mickeleit, M. and Lacmann, R., 1983. Statistical mechanics and thermodynamic properties of liquid multicomponent mixtures. Part I. The Taylor series for quasichemical equilibrium of ternary mixtures. Fluid Phase Equilibria, 12: 201–216. Formulas are developed for thermodynamic excess functions for ternary liquid mixtures. The basis is the quasilattice theory of liquids developed by Barker, combined with the quasichemical equilibrium of contact pairs developed by Guggenheim. All excess functions are derived from general thermodynamic formulas. The numbers of contact pairs are approximated by Taylor series. In order to ensure good convergence, these series have differing forms depending on the signs of the interchange energies. It is possible to calculate the numbers of different contact pairs in different degrees of the series (zeroth, first, second). The exact calculation of the quasichemical approximation is compared with the statistical solution, often called the zeroth approximation, and with the Taylor series. Whereas the zeroth approximation fails, the series show reasonable quantitative agreement, depending on the degree of the series and on the interchange parameters. It is concluded that the method provides a useful approach for mixtures containing three or more components, or for associated mixtures.