Densities, Ultrasonic Speeds, Viscosities, Refractive Indices, and Excess Properties of 1-Butyl-3-methylimidazolium Tetrafluoroborate + <i>N</i>-Methylacetamide Binary Mixtures at Different Temperatures
Neha Chaudhary, Anil Kumar Nain
Abstract
The thermophysical properties, viz., densities, ρ, ultrasonic speeds, u, viscosities, η, and refractive indices, nD, were measured for the binary liquid mixtures of 1-butyl-3-methylimidazolium tetrafluoroborate [Bmim][BF4] with N-methylacetamide [NMA] over the whole concentration range, including those of pure liquids, at temperatures T/K = 293.15–318.15 and at pressure p = 101 kPa. Experimental data were used to determine the excess molar volume, VmE, excess isentropic compressibility, κsE, excess speed of sound, uE, excess molar isentropic compressibility, Ks, mE, deviations in viscosity Δη, and deviations in refractive index, ΔϕnD. These parameters were fitted to the Redlich–Kister type polynomial equation. The partial molar volumes and partial molar compressibilities and excess partial molar volumes and excess partial molar compressibilities over the entire range of mole fraction and at infinite dilution were also determined. The observed negative values of VmE, κsE, Ks, mE, and Δη and positive values uEand ΔϕnD indicate the strong interactions between the component molecules of these mixtures.