Temperature and Pressure Dependence of the Electrical Conductivity of 1‑Butyl-3-methylimidazolium Bis(trifluoromethanesulfonyl)amide

Abstract

The electrical conductivities of the ionic liquid 1-butyl-3-methylimidazolium bis­(trifluoro­methanesulfonyl)­amide ([BMIM]­[Tf₂N]) have been determined between (273 and 353) K over an extended pressure range up to 250 MPa by both electrochemical impedance spectroscopy and conductance bridge techniques. The results obtained by the two techniques are generally in good agreement, within 3%, though the conductance bridge results yield lower values outside the experimental uncertainties at higher conductivities, that is, at higher temperature and lower pressures where the maximum deviation is −7%. The temperature and pressure dependence of both the conductivity and molar conductivity have been represented by modified Vogel–Fulcher–Tammann equations. The molar conductivity scales with the viscosity, with overlapping isobars and isotherms, so that a Walden plot, the logarithmic projection of molar conductivity versus fluidity (reciprocal viscosity), is a straight line with a similar slope (0.924) to those obtained for other 1,3-dialkylimidazolium ionic liquids