Effect of N,N’ -Dimethylformamide on Volumetric, Viscometric and Thermodynamic Behavior of Isomeric Butanols at (298.15 - 323.15)K

Abstract

Densities and viscosities of the isomers of Butanols ( n-Butanol, iso-Butanol and tert-Butanol ) and their binary mixtures with N,N’ –
Dimethylformamide (DMF) were measured at temperatures 298.15, 303.15, 308.15, 313.15, 318.15 and 323.15 K respectively covering
the whole composition range. Densities and viscosities for binary mixtures have been plotted against mole fraction of Butanols at different
temperatures. It shows continuous decrease in density on addition of n-Butanol, + iso-Butanol and + tert-Butanol in DMF. Excess molar
volumes, VE for the systems were found to be negative. The viscosities increase linearly up to 0.5 mole fraction and beyond this
concentration the viscosity increases rapidly for all mixtures. Excess viscosities, E for the systems were found to be negative, which
demonstrate that the Butanol solutions of DMF are highly non-ideal. The change of free energies (G#) increase gradually with increase in
the mole fraction of Butalnols for all mixture. Excess free energy change (G#E) for the systems were found to be negative. For all
Butanols, excess viscosities and excess free energies show minima in alcohol rich region. The excess viscosities and excess free energies of
activation for viscous flow are in the order: DMF + tert-Butanol > DMF + iso-Butanol > DMF + n-Butanol. Excess viscosity and excess
free energy data have been fitted by the least squares method to the four parameters Redlich-Kister equation.