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|Title:||Dielectric relaxation of associated ternary liquid mixture from high frequency conductivity measurement of solution|
Sit, S K
|Keywords:||Relaxation time;hf conductivity;Dipole moment;Solute-solute interaction|
|Abstract:||Dielectric relaxations of two binary (jk) polar mixtures like N-methyl acetamide (NMA) and acetone (Ac) as well as dimethyl sulphoxide (DMSO) and acetone(Ac) dissolved in non-polar solvents (i) benzene and carbontetrachloride were studied at 25, 30, 35, 40 and 25°C temperatures, respectively for 0.0,0.3, 0.5, 0.7, and 1.0 mole fractions xj of acetone under 9.88 GHz and 9.174 GHz electric field from complex high frequency conductivity σijk* =( σijk′ + jσijk″) measurement of the ternary solution. The relaxation times τjk's of the binary polar mixtures were estimated from the ratio of slopes of σijk″- wjk and σijk′- wjk curves at wjk→0 as well as the slopes of σijk″- σijk′ linear equations of existing method [Murthy et al., Indian J Phys, 63B (1989) 491). They are compared with the reported τ 's due to Gopalakrishna's method to indicate the validity of both the methods. The proposed method of ratio of slopes seems to be a better choice in which the polar - polar interactions are almost eliminated. The dipole moments μjk 's for both the methods were calculated in terms of slopes β's of σijk–wjk curves at wjk→0 and dimensionless parameters b's and compared with the reported μ's. The variations of τjk 's and μjk 's with xj of acetone for (NMA+Ac) and (DMSO+Ac) mixture at an experimental temperature are explained on the basis of solutesolvent (monomer) and solute - solute (dimer) associations like μjk-T curve of (NMA+Ac) mixture. The theoretical dipole moments μtheo's were measured from the available bond angles and bond moments of polar groups of the molecules. A little disagreement between measured μjk 's and reported μ 's may be due to inductive, mesomeric and electromeric effects of the polar groups of the molecules at different temperatures under high frequency electric field .The thermodynamic energy parameters like enthalpy of activation ΔHτ , entropy of activation ΔSτ and free energy of activation ΔFτ of (NMA+Ac) mixture were estimated from slopes and intercepts of In (τjkT) against 1/T curves for different xj of acetone from Eyring's rate theory to know the molecular dynamics of the systems.|
|ISSN:||0975-1041 (Online); 0019-5596 (Print)|
|Appears in Collections:||IJPAP Vol.45(06) [June 2007]|
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