Thermodynamic Properties of 1-Butyl-3-Methylimidazolium Hexafluorophosphate in the Ideal Gas State

Published

June 1, 2003

Author(s)

Y Paulechka, Gennady J. Kabo, Andrey V. Blokhin, O A. Vydrov, Joe W. Magee, Michael D. Frenkel

Abstract

Thermodynamic functions for 1-butyl-3-methylimidazolium hexafluorophosphate ([C(4)mim][PF6]) are reported in a range of temperatures from (5 to 550) K, based on new measurements by calorimetry. Heat capacities of the crystal, glass, and liquid phases for [C(4)mim] [PF6] were measured with a pair of calorimeters. A vacuum-jacketed adiabatic calorimeter was used at temperatures between (5 and 310) K, and a heat bridge-scanning calorimeter was used from (300 to 550) K. With the adiabatic calorimeter, the fusion T-fus = 283.51 K, Δ(cr)(1)H(m)(o) = 19.60 kJ(.)mol(-1), and the glass transition T-g = 190.6 K were observed. The [C(4)mim][PF6] test sample was determined to have a mole fraction purity of 0.9956 by a fractional melting analysis. Densities of the liquid were measured in a range of temperatures from (298 to 353) K with a pycnometer equipped with a capillary neck. An unexpected endothermal transition, with a very small enthalpy change of 0.25 J(.)g(-1) (0.071 M(.)mol(-1)), was observed in a range of temperatures from (394 to 412) K. Heat capacity jumps were determined at the glass transition Δ(gl)(1)C(s) = 81.69 J(.)K(-1.)mol(-1) and fusion Δ(cr)(1)C, = 44.8 J(.)K(-1.)mol(-1), and the observed entropy change at fusion is Δ(cr)(1)S (283.51 K) = 69.23 J(.)K(-1.)mol(-1).

Citation

Journal of Chemical and Engineering Data

Volume

48

Issue

No. 3

Pub Type

Journals

Keywords

ionic liquids, Langmuir and Knudsen methods, thermodynamic properties

Citation

Paulechka, Y. , Kabo, G. , Blokhin, A. , Vydrov, O. , Magee, J. and Frenkel, M. (2003), Thermodynamic Properties of 1-Butyl-3-Methylimidazolium Hexafluorophosphate in the Ideal Gas State, Journal of Chemical and Engineering Data (Accessed October 17, 2025)