Excess properties of (ethane + propane)(l) and (carbon monoxide + methane)(l)

Abstract

The excess molar enthalpies of (ethane + propane)(l) at 200 and 240 K and of (carbon monoxide + methane)(l) at 91.3 K have been determined with a batch calorimeter. The (ethane + propane) excess enthalpies were found to be small and to undergo a change in sign from positive to negative between 200 and 240 K. The excess enthalpies reported here, along with a previously published value reported for 112 K, were used in conjunction with published phase equilibria to develop a consistent expression for the excess molar Gibbs free energy between 112 and 255 K. The excess enthalpy against composition curve for { xCO + (1 − x)CH 4} was found to be skewed toward the methane-rich compositions with a maximum value of 107.3 J · mol −1 observed at x = 0.43. This resolved the uncertainty in the degree of asymmetry of H m E arising from the disagreement between two earlier investigations.