Thermodynamics of the Liquid System Methane+Propane

Abstract

The total vapour pressure of liquid mixtures of methane and propane has been measured as a function of composition at temperatures of 115.77 and 134.83 K. The activity coefficient of methane f\ and the excess Gibbs function of mixing GB have been evaluated from the vapour pressure measure ments, and the heat of mixing and the excess entropy of mixing SE have been estimated from the temperature dependence of GE and compared with direct calorimetric values. Values of the excess thermodynamic functions have been calculated from a simplified version of the Flory theory of mixtures, with allowance for departures from the geometric mean (Berthelot) combining rule. Calculations show that these deviations are very small, but not negligible.