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Pure Appl. Chem., 2013, Vol. 85, No. 1, pp. 201-210

Published online 2012-10-04

Extended excluded volume: Its origin and consequences

Ivo Nezbeda1,2* and Michael Rouha2

1 Faculty of Science, J. E. Purkinje University, 400 96 Ústí nad Labem, Czech Republic
2 Institute of Chemical Process Fundamentals, Academy of Sciences of the Czech Republic, 165 02 Prague 6 – Suchdol, Czech Republic

Abstract: In contrast to the common intuitive/speculative approach based on an analysis of thermodynamic or structural data of (nonpolar) fluids, the statistical mechanical approach is used to extend the excluded volume concept to all other types of fluids. The (extended) excluded volume incorporates, in addition to common nonelectrostatic interactions defining the shape and size of the molecules, also the short-range part of the repulsive interactions between the embedded Coulombic sites. In this study we show that the extended excluded volume concept correctly predicts the behavior of the partial molar volume (PMV) at infinite dilution in different solvents and, particularly, differences between nonpolar and associating solvents. The concept is then applied to estimate the PMV of methanol in water.