Thermodynamics of chloroform and methanol mixtures

Abstract

Heats of mixing and vapour pressures of chloroform (A)+ methanol (Bn) as a function of concentration have been determined at 303.15 K. The excess Gibbs free energy of mixing, GE values, have been obtained from the measured vapour pressure data. The heats of mixing values are negative for solutions rich in methanol but they become positive for solutions rich in chloroform. On the other hand, GE values are positive for all the methanol mole fractions and GE > HE. The results have been analysed in terms of Barker and ideal associated model theory of non-electrolyte solutions. The analysis has revealed that only the ideal associated model approach (which here assumes the presence of AmB (m = 1, 2), ABk (k = 2) and Bl (l = 1) molecular species) well describes the general behaviour of HE with xA over the entire chloroform concentration range for this mixture. The equilibrium constants for the various association reactions along with the enthalpy of formation of the various molecular species have also been calculated.