Thermodynamic properties of n-methylformamide + short carboxylic acids as a function of temperature

Abstract

Density, viscosity and speed of sound of three binary liquid systems: N-methylformamide (N-MFA) with carboxylic acids (ethanoic acid, propanoic acid and butanoic acid) have been determined at T = (303.15–318.15) K over the entire composition range. These experimental data have been used to calculate the excess volume (VE), excess isentropic compressibility (κsE), deviation in viscosity (Δη) and excess Gibbs free energy of activation of viscous flow (G∗E). The variations of these properties with composition of binary mixtures suggest loss of dipolar association, difference in size and shape of the component molecules, dipole–dipole interactions and hydrogen bonding between unlike molecules. The viscosity data have been correlated with Grunberg and Nissan, Katti and Chaudhri, and Hind et al. equations and the results are compared with the experimental results. The excess parameters have been fitted to the Redlich–Kister polynomial equation using multi parametric nonlinear regression analysis to derive the binary coefficients and to estimate the standard deviation.