CHEMICAL ASSOCIATION VIA EXACT THERMODYNAMIC FORMULATIONS

It can be fruitful to view two-component physical systems of attractiv e monomers, A and B, ''chemically'' in terms of a reaction Af B revers ible arrow C, where C = AB is an associated pair or complex. We show h ow to construct free energies in the three-component or chemical pictu re which, under mass-action equilibration, exactly reproduce any given two-component or ''physical'' thermodynamics. Order-by-order matching conditions and closed-form chemical representations reveal the freedo m available to modify the A-C, B-C, and C-C interactions and to adjust the association constant. The theory (in the simpler one-component, i .e., A = B, case) is illustrated by treating a van der Waals fluid. (C ) 1998 Elsevier Science B.V. All rights reserved.