Phase Equilibria and Thermodynamic Description of Alloys of 8-Hydroxyquinoline – 4-Chlorobenzoic acid

Abstract

In present article 8-hydroxyquinoline (HQ)-4-chlorobenzoic acid (CBA) system has been undertaken to study phase diagram and thermodynamic contribution in the system in terms of partial and integral mixing and excess functions. The phase equilibria of the system under taken shows the formation of 1:1 addition compound C and its eutectic E at 214º and199º c respectively. The negative value of molar free energy of mixing (?G^M) of alloys at 0.810 and 0.895 mole fraction of CBA suggests that the mixing in these cases is spontaneous. The integral molar enthalpy of mixing value corresponds to the value of excess integral molar free energy of the system favors the regularity in the binary solutions. The positive value of excess free energy (g^E) for all the eutectic and noneutectic alloys suggests an association of weaker nature between unlike molecules and of stronger nature between like molecules. Gibbs-Duhem equation gives the graphical solution of partial molar heat of mixing(?H_i^-M), activity and activity coefficient of a particular constituent in the binary mix. Interfacial roughness of the binary alloys has also been explained.

Keywords : Organic alloys, phase diagram, activity, activity coefficient, mixing  and excess function.