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.