Physico-chemical studies of non-aqueous binary liquid mixtures at various temperatures

Densities, rho, viscosities, eta, and ultrasonic velocities, u, have been measured for pure N,N-dimethylformamide (DMF), ethanol and their binary mixtures at 298.15, 303.15, 308.15, 313.15 and 318.15 K over the whole mole fraction range. From these data adiabatic compressibilities, 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 excess free energies of activation of viscous flow, G(*E), have been calculated. All the excess functions studied were found to be negative over the entire range of mole fraction. These properties are used to explain the intermolecular interactions between the components. Furthermore, activation enthalpies, Delta H* and entropies, Delta S* of viscous flow have been evaluated and their variations with concentration discussed.