Excess molar enthalpies of (ethane + ethene), (ethane + chloromethane), (propane + chloromethane), and (butane + chloromethane) calculated from cubic equations of state and the principle of corresponding states—a comparison with experimental results

Abstract

Excess molar enthalpies H m E are calculated using equations of state and the principle of corresponding states for four binary mixtures: (ethane + ethene), (ethane + chloromethane), (propane + chloromethane), and (butane + chloromethane), at temperatures from 298.15 to 363.15 K and pressures from 5 to 15 MPa, so that a comparison can be made with recently obtained experimental calorimetric results. Four cubic equations of state (van der Waals, Redlich-Kwong, Soave, and Peng-Robinson) and the principle of corresponding states, used together with the van der Waals one-fluid approximation (vdW1), are examined. The only adjustable parameter was the binary interaction parameter k 12 in Berthelot's combining rule. It was adjusted for each type of mixture and set at different values for the equation of state calculations or the principle of corresponding states prediction, but set independent of temperature, pressure, and a particular equation of state. Usually, reasonably good comparisons are obtained between the experimental results and the H m E( p, T) surface calculated from the equations of state and from the principle of corresponding states. (Vapor + liquid) equilibria for (ethane + chloromethane) at p = 5 MPa were also calculated using the k 12 determined from the H m E results, and compared with experimental results. The agreement is best for the Soave and the Peng-Robinson equations, with the other equations and the principle of corresponding states predicting equilibrium mole fractions that are low.