Measurement of the Viscosity, Density, and Electrical Conductivity of 1-Hexyl-3-methylimidazolium Bis(trifluorosulfonyl)imide at Temperatures between (288 and 433) K and Pressures below 50 MPa

The viscosity, density, and electrical conductivity of 1-hexyl-3-methylimidazolium bis(trifluorosulfonyl)imide have been measured at temperatures from (288 to 433) K and at pressures up to 50 MPa. A vibrating wire viscometer was used for the measurements of viscosity that have an expanded uncertainty ( k = 2) of ± 2 %. The density was obtained from a vibrating tube densimeter with an expanded uncertainty ( k = 2) of ± 0.3 %. The electrical conductivity κ( f →∞) was determined from impedance measurements at frequencies in the range (0.5 to 10) kHz with an expanded ( k = 2) uncertainty of ± 2 %. All measurements were conducted with a sample distributed by NIST as part of an IUPAC project. The water mass fraction was determined before and after the measurements. The viscosity and density of a sample with initial water content of 7·10 -6 were represented by interpolating expressions with standard deviations of 0.4 % and 0.03 %, respectively. Differences between the experimental and calculated values are comparable with the expanded ( k = 2) uncertainties. For temperatures that overlap the temperature range (288 to 433) K at p = 0.1 MPa, literature values of density differ by ≤ ± 0.2 % while the reported viscosities differ by ≤ ± 7 % from these empirical representations of the measurements. There are no values of the viscosity at p > 0.1 MPa reported in the literature to compare our results. At p > 0.1 MPa, the literature values for density reported by Gomes de Azevedo ( J. Chem. Thermodyn. 2005, 37, 888−899) deviate from our smoothing equation by less than −0.2 % at temperatures and pressure that overlap ours. The electrical conductivity was determined on a sample with initial water mass fraction of 90·10 -6 . The results were represented within the expanded uncertainty by an empirical function against which the literature values differed by no more than ± 5 %.