Thermodynamic properties of binary mixtures of methyl acetate and some selected ketonesat varying compositions and temperatures

Abstract

Density and viscosity measurements of binary mixtures of methyl acetate with propanone, butan-2-one and pentan-2-one were carried out at varying compositions (0 to 1) of methyl acetate and temperatures of 25, 30, 35 and 40◦C. The experimental data obtained were correlated with the Redlich-Kister polynomial equation from where excess molar volumes (VE ), excess viscosities (ηE), excess Gibbs free energies of activation for viscous flow (ΔG*E ), fitting coefficients and standard deviations of the mixtures were calculated. The ηE values were positive for mixtures of butan-2-one and pentan-2-one at all compositions and temperatures but gradually decrease with increasing composition and temperature. The mixtures of methyl acetate with propanone showed negative values of excess viscosity at all compositions of methyl acetate. The negative values are observed to be directly proportional to temperature. The values of VE for mixtures of methyl acetate + propanone system display positive deviations at lower compositions (0-0.4) and negative for higher mole fractions. The excess molar volumes of mixtures of butan-2-one and pentan-2-one are negative at the studied compositions and temperatures with a minimum at 0.3 composition and subsequent gradual decrease in negativity with increasing composition. The excess Gibbs free energy of activation for viscous flow (ΔG*E ) are positive at all compositions and temperatures and reaches a maximum at 0.3 composition above which it decreases. These results have been interpreted on the basis of the type and nature of interactions as well as differences in molecular architecture between the solvent mixtures.