Densities, speeds of sound, viscosities, refractive indices, excess and partial molar properties of binary mixtures of 1-butyl-3-methylimidazolium tetrafluoroborate with formamide at temperatures from 293.15 to 318.15 K

The densities, rho, speeds of sound, u, viscosities, eta and refractive indices, n(D) of the binary solutions of 1-butyl-3-methylimidazolium tetrafluoroborate [Bmim][BF4] with Formamide (FA), including those of pure liquids, have been measured over the whole range of composition at different temperatures (T/K = 293.15 to 318.15) and at atmospheric pressure, p = 101 kPa. The experimental data were used to calculate the excess properties such as excess molar volume,V-m(E), excess isentropic compressibility, K-S(E), excess speed of sound, u(E), excess molar isentropic compressibility, K-s,m(E), deviations in viscosity, Delta eta, deviations in refractive index, Delta(phi)n(D) and deviations in molar refraction, Delta R-M. These excess parameters were fitted to a 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 whole composition range; and at infinite dilution were also calculated. The obtained results were interpreted in terms of intermolecular interactions occurring in these mixtures. (C) 2020 Elsevier B.V. All rights reserved.