Physical theory for fluids of small associating molecules

The physical approach is used to derive a theory for the properties and phase equilibria of hydrogen-bonding and associating fluids. The theory accounts for nonpolar and multipolar interactions and for the strong and highly directional short-range attractive interactions which lead to association. For nonpolar and multipolar interactions, the u expansion of perturbation theory is used, and Wertheim's theory is used for association interactions. The theory is used to predict the properties of a variety of real fluids, with emphasis on the prediction of mixture phase behavior. The agreement with experiment is generally good