THERMODYNAMIC BEHAVIOR OF MIXTURES .1. MIXTURES OF PYRIDINE WITH BETA-PICOLINE, GAMMA-PICOLINE, ISOQUINOLINE, BENZENE AND CYCLOHEXANE AT 25-DEGREES-C

Ultrasonic velocities (u) and densities (rho) of mixtures of pyridine (Py) with beta-picoline, gamma-picoline, isoquinoline, benzene and cyclohexane have been measured over the whole composition range at 25-degrees-C. From u and rho data, various intermolecular interaction parameters such as Wada's constant (W), the molar sound velocity (u(m)) and the solvation number of the co-solvent (N(c)) have been calculated for these binary systems. The partial molar volumes (V(o)BAR) and isentropic compressibilities (kappa(s)OBAR) at infinite dilution have also been computed for all the co-solvents as well as for Py. The variation of the excess properties V(E) and kappa(S)E shows that Py-beta-picoline and Py-gamma-picoline have mild excess contributions in comparison to all other Py-co-solvent systems. The excess contributions for Py-isoquinoline and Py-benzene have been attributed to the strong specific interactions and that of Py-cyclohexane to the strong dispersive forces that operate between the components of the binary mixtures.