The study of solute–solvent interactions in 1-ethyl-3-methylimidazolium tetrafluoroborate + 2-ethoxyethanol from density, speed of sound, and refractive index measurements

Physical properties, such as density ( ρ ), speed of sound ( u ), and refractive index ( n D ) for pure [Emim][BF 4 ], 2-ethoxyethanol and their binary mixtures, are measured using Anton Paar vibrating tube density and sound velocity meter (DSA 5000 M) and automatic refract meter over the whole composition range as a function of temperature between 298.15 and 328.15 K in steps of 10 K at atmospheric pressure. Experimental values were used to calculate the excess molar volumes ( V m E ), excess values of partial molar volumes ( V ¯ m E ), partial molar volumes at infinite dilution ( V ¯ m E , ∞ ), isentropic compressibility ( κ s E ), acoustic impedance ( Z E ), free length ( L f E ) and deviations in speeds of sound ( u d ), and refractive index ( Δ ∅ n D ) for the binary mixtures. These excess/deviation properties are fitted to the Redlich–Kister-type equation to obtain the binary coefficients and the standard errors. A qualitative analysis of intermolecular interactions between the liquids in study is analyzed on the basis of the measured and the derived properties.