GEQUAC, AN EXCESS GIBBS ENERGY-MODEL FOR SIMULTANEOUS DESCRIPTION OF ASSOCIATING AND NONASSOCIATING LIQUID-MIXTURES

A physically founded model for the excess Gibbs energy, GEQUAC (Group- surface Explicit QUAsiChemical theory), presented here, allows the des cription of associating as well as non-associating liquid mixtures. Th is is achieved by explicit accounting for the different poles of the m olecular surface between which strong interactions take place in a mix ture. The model is tested against results of Monte-Carlo computer simu lations performed in lattice systems. Comparison of G(E), H-E and TSE determined from GEQUAC, computer simulations, and experiment shows tha t the thermodynamic behaviour of mixtures containing polar as well as hydrogen-bonding components can be modeled.