Equation of state based on a group contribution model applicable to vapor and liquid phases and its application to n-alkane systems.

An equation of state is derived from a group contribution model which takes into account the effect of local molecular distribution on potential energy in terms of the non-random two-liquid (NRTL) model. Model parameters for methyl and methylene groups are determined from the data reduction of saturated properties of n-alkanes. It is shown that the equation of state correlates well the saturated properties of "-alkanes and successfully predicts the vapor-liquid equilibria of n-alkane binary mixtures.