PHYSICOCHEMICAL STUDIES OF NONAQUEOUS BINARY-LIQUID MIXTURES AT VARIOUS TEMPERATURES

Densities, rho, viscosities, eta, and ultrasonic velocities, u, have b een measured for pure N,N-dimethylformamide (DMF), ethanol and their b inary mixtures at 298.15, 303.15, 308.15, 313.15 and 318.15 K over the whole mole fraction range. From these data adiabatic compressibilitie s, beta, intermolecular free lengths, L(f), relative associations, R(A ), excess adiabatic compressibilities, beta(E), excess free lengths, L (f)(E), excess molar volumes, V-E, excess viscosities, eta(E), and exc ess free energies of activation of viscous flow, G(E), have been calc ulated. All the excess functions studied were found to be negative ove r the entire range of mole fraction. These properties are used to expl ain the intermolecular interactions between the components. Furthermor e, activation enthalpies, Delta H and entropies, Delta S* of viscous flow have been evaluated and their variations with concentration discu ssed.