Pressure and temperature dependence of the excess thermodynamic properties of binary dimethyl carbonate + n-octane mixtures

Abstract

In this work we report several excess thermodynamic properties for the dimethyl carbonate + n-octane system in an effort to better understand their behavior over wide temperature and pressure ranges. From previous experimental pVTx data for this system, the changes in the excess molar Gibbs energies, in the excess molar entropies, and in the excess molar enthalpies due to pressure have been determined over a wide temperature range and for pressures up to 25 MPa. A correlation of the excess volume as a function of pressure was used for each composition and temperature, together with a new, recently proposed equation for the excess molar volume as a function of temperature, pressure, and composition. Excess molar enthalpies and excess molar Gibbs energies at 298.15 K and for pressures up to 25 MPa were calculated using literature data at atmospheric pressure. Furthermore, the excess isothermal compressibility, the excess isobaric expansivity, and the excess internal pressure were calculated. The expression for the internal pressure of an ideal mixture suggested recently by Marczak has been used.Key words: excess thermodynamic properties, dimethyl carbonate, n-octane, high pressure.