Ultrasonic and volumetric studies of molecular interactions in acetonitrile+1-alkanol (C6, C8, C10) binary liquid mixtures at different temperatures

The densities, rho, and ultrasonic speeds, u, have been measured in the binary liquid mixtures of acetonitrile (ACN) with I-hexanol, I-octanol and I -decanol, and in the pure components, as a function of composition at 25, 30, 35, 40 and 45 degreesC. The deviations in isentropic compressibility, Deltakappa(s), excess molar volume, V-E, deviations in ultrasonic speed, Deltau, apparent molar compressibility, K-phi.2, apparent molar volume, V-phi,V-2, partial molar compressibility, (K) over bar degrees(phi,2), and partial molar volume, (V) over bar degrees(2), of 1-alkanols in ACN have been calculated from the experimental data of densities and ultrasonic speeds. The variations of these parameters with composition of the Mixtures indicate that the structure-breaking effect dominates over that of the hydrogen-bonding effect between unlike molecules, suggesting that ACN-alkanol interaction is weaker than ACN-ACN and alkanol-alkanol interactions, and that the interaction (ACN-alkanol) follows the order: 1-hexanol > 1-octanol > 1-decanol. The excess molar volume data have been analysed by using Flory and Prigogine-Flory-Patterson theories. Further, the ultrasonic speeds in these Mixtures were theoretically calculated with the help of several theories and empirical relations using the Pure component data. The validity and relative merits of these theories and relations have been discussed.