Calculation and prediction of thermodynamic properties of non-electrolyte mixtures with a new quasi-chemical approximation

Using the old, modified TASQUAC model [1-3], only small negative excess ent ropies of mixing can be described with model assumptions. Intra- and interm olecular vibrations and the rotation of molecules are also not considered. In this work, therefore, a new relationship for the interaction energy with an enthalpy (Delta h) and an entropy parameter (Delta s) in the quasi-chem ical approximation is suggested. The exact solution for the quasi-chemical equilibrium in the two-component mixture is given, and a new model for desc ribing and predicting phase equilibria in multi-component systems S-TASQUAC is developed. We examined the possibilities of using S-TASQUAC to predict VLE data and compared the results of binary systems to the results of other known models of liquid mixtures (Wilson, NRTL, UNIQUAC). The results of th e calculated data demonstrate the usability of S-TASQUAC as a qualified too l to describe and predict phase equilibria.