Excess molar enthalpies of methanol-n-pentane and methanol-n-hexane from 454.4 to 522.7 K and up to 6 MPa

Flow calorimetric measurements of the excess molar enthalpy, HEm, of (0.5CH3OH + 0.5C5H12)(g) and (0.5CH3OH + 0.5C6H14)(g) are reported. The measurements extend over the temperature range 454.4–522.7 K and at pressures up to 6 MPa. Residual enthalpies of n-pentane and n-hexane were calculated from the equation of state proposed by Kubic, and the residual enthalpy of methanol was calculated from a modification of Kubic's equation proposed by Massucci and Wormald. For methanol in its interaction with n-alkanes there is no hydrogen bonding, and to obtain equation of state parameters for this interaction a pseudo-critical temperature of 270 K and a pseudo-critical pressure of 4.99 MPa for methanol were used. With these parameters, the measurements on both mixtures could be fitted using the usual one-fluid combining rules.