EXCESS-ENTHALPIES FOR (PENTANE PLUS METHANOL) AT THE TEMPERATURES (283.15, 298.15, AND 363.15)-K AND THE PRESSURES (0.4, 5, AND 15) MPA

Excess molar enthalpies are reported over the composition range from x ≈ 0.02 to x ≈ 0.96 for {xCH3(CH2)3CH3 + (1 - x)CH3OH} at the temperatures (283.15, 298.15, and 363.15) K and the pressures (0.4, 5, and 15) MPa. The excess molar enthalpies obtained at the pressure and temperature conditions where both components are liquid are positive and have a small pressure coefficient, but a large temperature coefficient CEp, m. These results are typical of those obtained when a liquid alkane is mixed with a liquid alkanol at temperatures well below the critical temperature of the alkane. (Liquid + liquid) equilibrium is present at T = 283.15 K. The resulting HEm (x) curves show a linear region where incomplete mixing occurs. At p = 0.4 MPa and T = 363.15 K, pentane is gaseous and methanol is liquid, and HEm (x) changes from a small negative value at low x to a large positive value at higher x with a linear HEm (x) between, resulting from (vapor + liquid) equilibrium. The negative HEm (x) is due principally to a contribution resulting from the condensation of the gaseous pentane into the liquid methanol, while the large positive region results principally from the vaporization of the liquid methanol into the gaseous pentane. © 1994 Academic Press Ltd.