Association effects in ternary vapour—liquid equilibria

A thermodynamic model is proposed for the analysis of multicomponent systems capable of homo and heteroassociation between all the chemical species present. Detailed equations have been developed for ternary systems. The method has been applied to the experimental vapour—liquid data obtained for the system formic acid—acetic acid—propionic acid at 760 mm Hg. The calculated activity coefficients were thermodynamically consistent and were correlated using the Redlich—Kister equation. Boiling points, compositions and activity coefficients can be predicted from the vapour—liquid equilibrium data of the three binary systems.