Ultrasonic and viscometric study of molecular interactions in binary mixtures of aniline with 1-propanol, 2-propanol, 2-methyl-1-propanol, and 2-methyl-2-propanol at different temperatures

Ultrasonic speeds, u and viscosities, η of pure aniline, 1-propanol, 2-propanol, 2-methyl-1-propanol, 2-methyl-2-propanol, and their binary mixtures with aniline as common component, over the entire composition range were measured at the temperatures 293.15, 298.15, 303.15, 308.15, 313.15 and 318.15 K. From the experimental data, the deviations in isentropic compressibility, Δks, and in viscosity, Δη   were calculated. The partial molar compressibilities, K¯m,1 and K¯m,2 of aniline and alkanols in the mixtures over the whole composition range and K¯m,1° and K¯m,2° at infinite dilution and excess partial molar compressibilities, K¯m,1E and K¯m,2E, over the whole composition range and K¯m,1°E and K¯m,2°E at infinite dilution were calculated by using two different approaches. The variation of these parameters with composition and temperature of the mixtures has been discussed in terms of molecular interaction in these mixtures. It is observed that aniline–alkanol interaction in these mixtures follows the order: 1-propanol < 2-propanol < 2-methyl-1-propanol < 2-methyl-2-propanol, and Δks values depend upon the number and position of hydroxyl and alkyl groups in these alkanol molecules. Furthermore, the free energies, ΔG*, enthalpies, ΔH* and entropies, ΔS* of activation of viscous flow have also been obtained by using Eyring viscosity equation and their dependence on composition of the mixtures have been discussed.