Ultrasonic velocity in binary mixtures under high pressures and their thermodynamic properties I : binary mixture for nitrobenzene-aniline

The ultrasonic velocities in a binary mixture of liquid nitrobenzene and aniline were measured at temperature 30℃ and pressures up to freezing pressures or 2100 bar (10^5Pa) by a pulse technique of fixed-path type at a frequency of 1 MHz, with an estimated error of less than 0.3 percent. The ultrasonic velocities in a binary mixture at atmospheric pressure increase with increasing mole fraction of aniline, but the data at near 0.5 mole fraction of aniline deviated from the smooth curve. The ultrasonic velocity is found to increase parabolically with increasing pressure. Using the measured values of ultrasonic velocity and the P-V-T relations reported in the literature, the adiabatic compressibility, the specific heat ratio and the specific heat at constant pressure have been derived under each condition. At atmospheric pressure, the results for pure liquids were in a good agreement with experimental values in the literature. It was also found that the measured values of ultrasonic velocity showed an unusual behavior indicating the existence of some intermolecular interactions between nitrobenzene and aniline