Volumetric and Viscometric Studies of Molecular Interactions in Binary N,N-Dimethylacetamide + Benzyl Alcohol Mixtures at Different Temperatures
The densities, ρ, and viscosities, η, of pure N,N-dimethylacetamide (DMA) and benzyl alcohol (BA), and nine of their binary mixtures covering the entire composition range have been measured at 25, 30, 35, 40 and 45°C. The experimental ρ and η values were correlated with composition and temperature by using some empirical relations. The excess volumes, VE, deviation in viscosities, Δη , excess Gibbs energies of activation of viscous flow, ΔG*E, and paal molar volumes, Vo1 and Vo2 ,of DMA in BA and BA in DMA, respectively, at infinite dilution have been evaluated from the experimental data. The variations of these parameters with composition and temperature indicate the presence of specific interactions, namely hydrogen bonding and dipole-dipole forces between unlike molecules, which decrease with rise in temperature. Furthermore, the enthalpies, ΔH*, and entropies, ΔS*, of activation of viscous flow have also been obtained by using the Eyring viscosity equation and fitting the results to some empirical relations. The ΔH* values were found to be dependent on temperature. The dependencies of ΔH* and ΔS* on the compositions of the mixtures have been discussed.
Keywords: Density, viscosity, binary mixtures, molecular interactions.
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