The quasi-chemical approach for non-randomness in liquid mixtures. Expressions for local surfaces and local compositions with an application to polymer solutions

(p, Vm, T, x) measurements of dimethyl carbonate+octane binary mixtures: I. Experimental results, isothermal compressibilities, isobaric expansivities and internal pressures

Thermophysical properties of four binary dimethyl carbonate + 1-alcohol systems at 288.15-313.15 K

Volumetric properties and viscosities of the methyl butanoate + n-heptane + n-octane ternary system and its binary constituents in the temperature range from 283.15 to 313.15 K

The basic constraint for any valid expression for local composition, derived by McDermott and Ashton, is shown to be equivalent to the conservation equation used in Flemr's analysis. A similar constraint for local surface fractions is derived. The applicability of quasi-chemical expressions for local composition or local surface area fractions is extended to different existing (random) models of solutions. Chao's and Kehiaian's treatments appear as special cases. The statistical thermodynamic derivation of UNIQUAC is discussed in the framework of the generalized treatment. A method for solving the quasi-chemical equations for quaternary systems is described.



On montre que la contrainte fondamentale etabilie par McDermott et Ashton, relativement a n'importe quelle expression valable de la composition locale, est equivalente a l'equation de conservation employee dans l'analyse de Flemr; on etablit une contrainte semblable pour les fractions locales de surface. On a etendu a differents modeles (aleatoires) de solutions existants, l'applicabilite d'expressions quasi-chimiques pour les compositions locales ou les fractions locales de surface. Les traitements de Chao et de Kehiaian apparaissent comme des cas particuliers. On discute la derivation par thermodynamique statistique d'UNIQUAC dans le cadre du traitement generalise. On decrit une methode pour resoudre les equations quasi-chimiques relatives aux systemes quaternaires.

Local compositions and local surface area fractions: A theoretical discussion

A group contribution molecular model is developed for the thermodynamic properties of polar and nonpolar liquids and their solutions, including energy of vaporization, ρVT relations, excess properties, and activity coefficients. The model is based on the cell theory in which the repulsive forces of molecules are expressed with a modified cell partition function derived from the Carnahan-Starling equation of state for hard spheres. The attractive forces are made up of group pair interaction contributions. Group and interaction properties have been determined for methyl, methylene, hydroxyl, and carbonyl. Extensive comparisons are made of predictions of the model with data for pure liquids and their solutions.

Tomoshige Nitta

Papers

A group contribution molecular model of liquids and solutions