Molecular Interaction Study of Binary Mixtures of THF with Methanol and o-Cresol - an Optical and Ultrasonic Study

The refractive indices, densities and ultrasonic velocities of binary liquid mixtures of tetrahydrofuran (THF) with methanol and o-cresol over the entire composition range have been measured at 293, 303 and 313 K. Refractive index, density and ultrasonic velocity data have been used to evaluate the molar refraction deviation $ΔR_{m}$, deviation in ultrasonic velocity Δu, excess internal pressure $π_{i}^{E}$, excess molar enthalpy $H_{m}^{E}$ and excess free volume $V_{f}^{E}$. The computed results of $ΔR_{m}$, Δu, $π_{i}^{E}$, $H_{m}^{E}$ and $V_{f}^{E}$ were fitted to the Redlich-Kister polynomial equation. These results suggest that specific strong interactions are taking place in THF + o-cresol mixture while dispersive forces seem to be responsible for behaviour of THF + methanol mixture. Further, experimental refractive index and density data of these mixtures were also used to test the validity of the empirical/semi-empirical relations and models for refractive index and density, respectively.