Thermodynamic properties of a lattice model of aqueous mixtures

Abstract

The thermodynamic anomalies of water have been studied for a long time by statistical models that incorporate the effects of hydrogen bonding in a qualitative manner by adding certain orientational degrees of freedom. In this paper, we study how these anomalies are carried over to aqueous mixtures, in which the other component molecules form van der Waals bonds with water molecules as well as among themselves. For this purpose we adapt a recent model due to Sastry et al., which is quite successful in exhibiting these anomalies for pure water. In particular, we have studied how anomalous behavior of density and compressibility varies with composition over a range of temperatures and pressures. We have also obtained a few typical phase diagrams for these mixtures.