Acoustical and excess thermodynamic studies of binary liquid mixtures at varying temperature using ultrasonic technique

The ultrasonic velocity, density and viscosity of binary liquid mixtures of lactic acid with methanol, 1-propanol and 2- propanol of various compositions at 308 K, 313 K, 318 K and 323 K were determined. These experimental data have been used to estimate the thermodynamic parameters such as adiabatic compressibility (β),free length (L _f ), free volume (V _f ), internal pressure (π _i )and enthalpy (H). The excess values of the above parameters like excess adiabatic compressibility, excess free length, excess free volume, excess internal pressure and excess enthalpy are also evaluated in order to dispute the nature of molecular interactions present among the constituent molecules of binary liquid mixture systems.