Matching equation of state mixing rules to activity coefficient model expressions

Procedures for deriving equation of state mixing rules based on matching the zero pressure excess Gibbs energy to that of a previously parameterized activity coefficient model are discussed. I have investigated the conditions required for accurate reproduction of the original model and provide a simple graphical tool for evaluating the error of the equation of state mixing rule. An extension of the MHV-2 mixing rule to incorporate mixtures containing components with very low volatility is suggested.