Ultrasonic and Optical Studies of Binary Mixtures of Ethanol with Diisopropyl Ether, Cyclohexane or n-Alkanes (C6-C9) from 298.15 to 318.15 K

Abstract

Ultrasonic speeds (u) and refractive indices (n) of the binary liquid mixtures of ethanol with diisopropyl ether (DIPE) or cyclohexane or n-alkane (C6-C9) were experimentally measured from 298.15 to 318.15 K over entire composition range. Using these measurements deviation in ultrasonic speed (Δu), deviation in refractive index (Δn), excess intermolecular free length (Lf E ) and excess isentropic compressibility (Ks E ) were calculated and fitted with Redlich-Kister equation. The Δu values are negative for all binary mixture and magnitude of negative deviation for binary mixture of ethanol and n-alkane decreases as chain length increases. At equimolar composition, Ks E follows the order: n-hexane > n-heptane >n-otcane > n-nonane > diisopropyl ether > cyclohexane. Experimental results were analyzed to understand the various molecular interactions present in the binary mixtures. The u values for all binary liquid solutions were also correlated using different empirical correlations such as Nomoto, impedence dependence relation and van Dael ideal mixing relation. The u for binary liquid mixtures were also computed theoretically using Schaaff′s collision factor theory. Free length theory was used to compute inter-molecular free length (Lf E ). Various correlations e.g., Arago-Biot (A-B), Gladstone-Dale (G-D), Heller (H), Lorentz-Lorentz (L-L), Eyring-John (E-J), Newton (Nw) and Weiner (W) were used for calculating refractive indices of selected systems theoretically.