Density, Viscosity, Refractive Index, Excess Molar Volume, Viscosity, and Refractive Index Deviations and Their Correlations for the (Formamide + Water) System. Isobaric (Vapor + Liquid) Equilibrium at 2.5 kPa

Abstract

Density, viscosity, and refractive index measurements for pure formamide and water at T = (293.15, 303.15, 313.15, and 323.15) K as well as for the binary system {x1 formamide + (1−x1) water} at the same temperatures were made over the whole concentration range. Isobaric (vapor + liquid) equilibrium at P = 2.5 kPa for this binary system was also measured. The experimental results of density, viscosity, and refractive index were fitted to empirical equations, which makes it possible to calculate these properties over the whole studied concentration and temperature ranges. Calculated values are in good agreement with the experimental results. Data of the binary mixture were further used to calculate the excess molar volume, viscosity and refractive index deviations, and the activity coefficients. The excess or deviation properties were fitted to the Redlich–Kister polynomial relation to obtain their coefficients and standard deviations. This binary system shows negative deviations from the ideal behavior and no azeotrope.