Thermophysical properties of binary mixtures of N,N-dimethylformamide with three cyclic ethers

Abstract

Densities and viscosities of the binary mixtures consisting of tetrahydrofuran (THF), 1,3-dioxolane (1,3-DO) and 1,4-dioxane (1,4-DO) with N,N-dimethylformamide (DMF) over the entire range of composition were measured at temperatures 298.15, 308.15 and 318.15 K and at atmospheric pressure. Ultrasonic speeds of sound of these binary mixtures were measured at ambient temperature and atmospheric pressure (T = 298.15 K and P = 1.01?105 Pa). The various experimental data were utilized to derive excess molar volumes (VmE), excess viscosities (?E), and excess isentropic compressibilities (?sE). Using the excess molar volumes (VmE), excess partial molar volumes (and ) and excess partial molar volumes at infinite dilution (and ) of each liquid component in the mixtures were derived and discussed. Excess molar volumes (VmE) as a function of composition at ambient temperature and atmospheric pressure were used further to test the applicability of the Prigogine-Flory-Patterson (PFP) theory to the experimental binaries. The excess properties were found to be either negative or positive depending on the nature of molecular interactions and structural effects of liquid mixtures. Em,1V Em,2VE0,m,1VE0,m,2V.