Dielectric relaxation study of binary mixtures of ethyl alcohol and N,N-dimethylformamide in benzene solution from microwave absorption data

Dielectric constant (epsilon') and dielectric loss (epsilon") of ethanol (C H;OH) and binary mixtures of ethanol and N, N-dimethylformamide (DMF) in benzene solutions have been measured at microwave frequency 9.883 GHz at different temperatures 25, 30, 35 and 40 degrees C. Standing microwave techniques and Gopala Krishna's [Traps Faraday Soc, 33 (1957)767.] single frequency concentration variation method have been used for above measurements. The measured values of epsilon' and epsilon" have been used to evaluate dipole moment (mu) and relaxation time (tau). Various thermodynamic parameters (Delta H-epsilon, Delta F-epsilon, and Delta S-epsilon) for the dielectric relaxation process of binary mixtures containing 50% mole fraction of OH have been calculated using Eyring's rate equations. Comparison has been made with the corresponding energy parameters for viscous flow process. It is found that the dielectric relaxation process can be treated as the rate process like the viscous flow process. Non-linear variation of relaxation time with molar concentration of ethanol in the whole concentration range of the binary mixture indicates the existence of solute-solute type of molecular association.