Excess molar enthalpies of six (carbon dioxide plus a polar solvent) mixtures at the temperatures 298.15 K and 308.15 K and pressures from 7.5 MPa to 12.6 MPa

The excess molar enthalpies H-m(E) of five binary mixtures: (carbon dioxide + methanol, or ethanol, or N-methyl-2-pyrrolidone, or methyl cyanoacetate, or N-formyl morpholine), and one ternary mixture: [xCO(2) + (1 - x){0.8085(CH2)(4)SO2 + 0.1915H(2)O}] were measured at the temperature T = 298.15 K and pressures near (7.5, 10.0, and 12.5) MPa. Values for H-m(E) of {xCO(2) + (1 - x)C2H5OH} and [xCO(2) + (1 - x){0.8085(CH2)(4)SO2 + 0.1915H(2)O}] were also measured at T = 308.15 K and the pressures (7.5, 10.0, and 12.5) MPa. Values of H-m(E){xCO(2) + (1 - x)(CH3OH or C2H5OH)} were negative for x < 0.8 and positive at higher x. The H-m(E) values for the other mixtures were negative al all compositions studied. Large negative values of H-m(E) were observed al T = 303.15 K and p = 7.5 MPa, consistent with the proximity to the critical temperature and pressure of carbon dioxide. (Vapour + liquid) phase boundaries were determined from the H-m(E) values for [xCO(2) + (1 - x){0.8085(CH2)(4)SO2 + 0.1915H(2)O}]. (C) 1996 Academic Press Limited