The determination of excess thermodynamic functions of binary liquid mixtures

Abstract

The work involved the determination of excess thermodynamic functions of binary liquid mixtures by experimental and theoretical means. Experimentally, excess Gibbs functions(GE), and excess volumes(VE) were determined. The theoretical work involved these functions as well as excess enthalpies(HE).
GE values were determined experimentally by the dew point-bubble point method(DPBP). The work involved development of a previously designed apparatus. A new procedure was realised and adopted. In the new procedure, fixed quantities of material were used for obtaining required dew point pressures and bubble point pressures. As a complementary part of measuring GE, a computer program was developed. Two systems were subjected to experiment. One of them, benzene+cyclohexane, produced results which compared well with published data. The system benzene+hexane produced results which were a marked improvement on previous DPBP work. After a discussion of the results, improvements on apparatus design were suggested.
Excess volumes were meassured by batch dilatometry. Four systems were used for testing the procedure. Then measurements on binary systems that have not been measured previously were made.
Theoretical aspects of the work involved applying various theories of fluids to the prediction of excess functions. One group of these theories was based on the principle of corresponding states. Experimental data of a number of pure substances were analysed to produce some universal relations. The other group of theories was based on equations of state which are analyt.ical in essence. The main new feature in this part of the work was the way in which various combining rules were used in conjunction with the different equations of state. Computer programs were developed so that a multiplicity of combinations was available for predicting excess functions.