Comparative thermo-acoustic study of ternary mixture of polar and nonpolar solvents with benzene and ethanol system

Abstract

The study of liquid mixtures containing polar or nonpolar components finds wide application in industrial and technological processes. The ultrasonic velocity (u) and density (ρ) of the ternary mixtures 1,2 propane-di-ol (polar) + ethanol + benzene (system I) and n-hexane (nonpolar) + ethanol + benzene (system II) as well as of pure components have been measured at 303 K temperature and at 2 MHz frequency. The ultrasonic velocity is measured using ultrasonic interferometry technique, and density is measured using relative density bottle. From these measured data, the excess acoustic parameters: excess ultrasonic velocity (uE), excess density (ρE), excess adiabatic compressibility (βE), excess intermolecular free length ( $$L_{\text{f}}^{\text{E}}$$ ), excess molar volume ( $$V_{\text{m}}^{\text{E}}$$ ) and excess acoustic impedance (ZE), have been calculated using standard relations. The variations in sign and values of excess acoustic parameters of the two systems help us to know the interaction and structural arrangement of the liquid mixture. The values of uE and ZE for system I show that the interaction changes from strong to weak interaction with increasing concentration and for system II it has dispersive-type interaction. There is an opposite trend in the values of ρE, βE, L f E and V m E for systems I and II. System I has smaller molar volume difference compared to system II, but relatively stronger Hp–π interaction gives it a compact structure. However, system II is more compressible due to dispersive-type interaction. Our work helps to understand the effect of the molecular interaction on behavior of liquid mixture of polar and nonpolar solvents in π-system clearly and concisely.