Study of Molecular Interactions in Ternary Mixtures of Quinoline with o-cresol, m-cresol and p-cresol in Methanol at T= 303.15, 308.15, 313.15, and 318.15 K

Aims: To evaluate the thermodynamical parameters and their excess functions to find the molecular interactions between unlike molecules in ternary liquid mixtures.

Study Design: Ultrasonic velocities, densities and viscosities have been measured for the ternary mixtures of quinoline with cresols in methanol at different temperatures (303.15, 308.15, 313.15 and 318.15K) over the entire range of mole fraction. These measurements are used to evaluate thermodynamical parameters like adiabatic compressibility (β), free length (Lf), free volume (Vf), internal pressure (π), acoustic impedance (Z) and enthalpy (H) were calculated. From these values the excess properties such as excess adiabatic compressibility (βE), excess free length (LfE), excess free volume (VfE), excess internal pressure (πE), excess acoustic impedance (ZE) and excess enthalpy (HE) are calculated.

Place and Duration of Study: Department of Physics and Department of Chemistry, V.R. Siddhartha Engineering College, Vijayawada, between April 2012 and June 2013.

Methodology: The liquids were purified according to the standard procedures. Ultrasonic velocities of pure liquids and liquid mixtures were measured using ultrasonic interferometer, densities and viscosities were measured by using specific gravity bottle and Ostwald’s viscometer.

Results: Excess adiabatic compressibility, excess free length and excess free volume exhibit negative values over the entire range of composition. In the first two systems the excess enthalpy values are found to be positive at lower mole fractions and negative for higher mole fraction range and at higher temperatures, whereas for system-3 these values are positive at all mole fractions and at temperatures 303.15, 308.15K and negative at temperatures 313.15 and 318.15K.

Conclusion: These data are required in the development of models for energy efficiency.