Thermodynamic properties of n-methylformamideþshortcarboxylic 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 T¼(303.15e318.15) K over the entire compositionrange. These experimental data have been used to calculate the excess volume (VE), excess isentropic compressibility (ksE), de-viation in viscosity (Dh) and excess Gibbs free energy of activation of viscous flow (G*E). The variations of these properties withcomposition of binary mixtures suggest loss of dipolar association, difference in size and shape of the component molecules,dipoleedipole interactions and hydrogen bonding between unlike molecules. The viscosity data have been correlated withGrunberg and Nissan, Katti and Chaudhri, and Hind et al. equations and the results are compared with the experimental results. Theexcess parameters have been fitted to the RedlicheKister polynomial equation using multi parametric nonlinear regression analysisto derive the binary coefficients and to estimate the standard deviation.