Dielectric and excess dielectric constants of binary liquid mixtures : Chlorobenzene + nitrobenzene, cyclohexanone + nitrobenzene and benzene + nitrobenzene at 303 K

摘要

The nonideal behaviour of liquid mixtures are characterized by excess thermodynamic properties such as excess volumes, enthalpy of mixing, compressibilities etc. The excess dielectric constant ε~E is also one such parameter that indicates the strength and nature of intermolecular interactions in binary liquid mixtures. The positive deviations from ideal behaviour (ε~E being positive) are qualitatively attributed to a "build in" of components of the mixture in the structure of respective solvent. The negative deviations from ideal behaviour (ε~E being negative) is explained qualitatively either due to interstitial solvation or due to breaking of aggregates. In the present study, the excess dielectric constants for the binary liquid mixtures (1) benzene + nitrobenzene, (2) chlorobenzene + nitrobenzene and (3) cyclohexanone + nitrobenzene are measured at 303 K and at different concentrations. The dielectric constants for these binary liquid mixtures are measured using a computer based system. It is based on the principle that the change in frequency of XR-2206 function generator, when the liquid forms the dielectric medium of the dielectric cell, is measured with a personal computer. The programmable interval timer 8254 available in the DIOT card is used to measure the frequency which in turn determines the capacitance of the cell and dielectric constant. The necessary software is developed in C language.