Some thermophysical properties of methanol and aqueous methanol mixtures at sub- and supercritical conditions

Expressions for the composition dependence of the critical constants of mixtures or water and methanol are presented as are expressions of the vapor pressure, the molar enthalpy of vaporization, and the molar volume of methanol along its saturation curve. The internal pressure of saturated methanol is compared with it cohesive energy density, reflecting the diminishing strength of its intermolecular hydrogen bonding as the temperature is increased. Thermophysical properties (molar volumes, isobaric expansibilities, isothermal compressibilities, and internal pressures) of mixtures of methanol and water at subcritical temperatures at saturation and at the fixed pressures of 7 and 20 MPa have been calculated and are presented in a table. The self- and mutual association of water and methanol in their mixtures at sub-critical temperatures is examined.