Dielectric relaxation in solutions chlorobenzene–benzene and chlorobenzene–hexane

Abstract

This paper presents the results of a study of the dielectric constant of solutions of a polar liquid in a nonpolar solvent: chlorobenzene–benzene, chlorobenzene–hexane. The measurements were carried out at a wavelength [Formula: see text][Formula: see text]cm in the temperature range from [Formula: see text]C to [Formula: see text]C. The studies were carried out using the dielectric spectroscopy method. This method allows a more detailed study of the dielectric properties of the objects of study due to the large equilibrium (“static”) dielectric constant of the object. The temperature dependence of the dielectric relaxation time of molecules in the liquid and solid states of the studied solutions is determined. It has been established that with increasing concentration (0.300, 0.562, 0.794, 1.000 for a chlorobenzene–hexane solution and 0.179, 0.368, 0.567, 0.778, 1.000 for a chlorobenzene–benzene solution) of the halogen substituent, the relaxation time increases. The measurement results of dielectric constant [Formula: see text] and absorption coefficient [Formula: see text] obtained for concentrated solutions chlorobenzene–benzene, chlorobenzene–n–hexane at wavelengths [Formula: see text], 80 and [Formula: see text][Formula: see text]cm at temperature [Formula: see text]C are given in the paper. The static dielectric constant is obtained at a frequency of 1[Formula: see text]MHz. The obtained experimental values [Formula: see text], [Formula: see text] and [Formula: see text] of investigated systems in ([Formula: see text], [Formula: see text]) plane locate on the semi-circle the center of which is on [Formula: see text] axis. In this case, the high-frequency limit value of [Formula: see text] dielectric coefficient exceeds the corresponding n2 refraction index square. The macroscopic and molecular relaxation times are calculated on the base of experimental data. The thermodynamic quantities characterizing the process of dielectric relaxation are calculated for solutions of chlorobenzene–benzene, chlorobenzene–hexane. It has been determined that the height of the potential barrier separating the two equilibrium positions of a polar molecule is greatest in the state of a pure polar liquid and decreases with dilution in a nonpolar solvent.