Enthalpy of mixing of liquid (carbon dioxide + ethane) at the temperature 230.8 K and of liquid (carbon dioxide + n-butane) at 221.4 K and 241.4 K

Abstract

A cryogenic flow calorimeter was used to measure excess molar enthalpies HEm for {xCO2 + (1 − x)C2H6}(l) at the temperature (230.8±0.5) K and the pressure (1.57±0.19) MPa and {xCO2 + (1 − x)n-C4H10}(l) at (221.4±0.4) K and (0.91±0.06) MPa, and at (241.4±0.2) K and (1.83±0.14) MPa, as a function of x. Raising the pressure in the first mixture to 3.37 MPa and in the second to 4.36 MPa at the higher temperature had no effect on HEm, within experimental error. The dependence of HEm on x shows a slight asymmetry toward the CO2-rich side For the first mixture, the value of HEm(x = 0.5) is (1626±6) J·mol−1, almost 200 J·mol−1 larger than previously published results (Wallis, K. P; Clancy, P.; Zollweg, J. A.; Streett, W. B. J. Chem. Thermodynamics 1984, 16, 811) while for the second, HEm(x = 0.5) is (1726±7) J·mol−1 and (1630±17) J·mol−1 at 221.4 K and 241.4 K, respectively.