Effect of the association of alkanols on their thermodynamic properties

Abstract

After a short discussion on the association models of alcohols from the point of view of activity concepts, the peculiarities of association in the equation of state concept are treated in detail, with restriction to high densities. It is shown that there association appears only as an integral value, where the integral (called the Helmholtz energy integration constant) is over the non-linearity correction to the attractive van der Waals term. Association is not seen in the hard convex bodies mixing rules, which means that isothermal compressibilities of alcoholic mixtures can be predicted from the knowledge of excess volume. The peculiarities of the Helmholtz energy integration constant cause the entropy of pure alcoholic liquids to be quite different from that of the hard convex body assembly, and present some problems in the treatment of mixtures.