Dielectric relaxation of ethanol and N-methyl acetamide polar mixture in C 6 H 6 at 9.90 GHz

Abstract

Debye relaxation times (τ j k ) and dipole moments (μ j k ) of binary (j k) polar mixtures of ethanol (EtOH) and N-methyl acetamide (NMA) dissolved in benzene(i) are studied by studying conductivity of solution at 9.90 GHz for different temperatures, different mole fractions (x j ) of ethanol and different weight fractions (w j k ) of the mixtures, respectively. The variation of τ j k −x j from linear slope of imaginary $(\sigma _{ijk}^{\prime \prime } )$ against real $(\sigma _{ijk}^{\prime })$ part of total conductivity $(\sigma _{ijk}^{\ast })$ curve reveals solute–solute (dimer) or solute–solvent (monomer) molecular associations up to x j = 0.0−0.3 and thereafter, solute–solvent molecular associations. τ j k s from the ratio of slopes of $\sigma _{ijk}^{\prime \prime }-w_{jk} $ and $\sigma _{ijk}^{\prime }-w_{jk} $ curves exhibit solute–solvent molecular association for all x j s which are consistent with the μ j k −x j curves at all temperatures except at 35∘C. This signifies the validity of both the proposed methods in estimating τ and μ. The molecular dynamics of the polar mixture are ascertained from Eyring rate theory. Theoretical dipole moments from bond angles and bond moments (μ theo) are also calculated to predict associational aspects.