ABSTRACT

The heat capacities of nine room-temperature ionic liquids (ILs) were measured in an adiabatic calorimeter. The obtained results were compared with the literature data. It was demonstrated that in most works the uncertainty of the heat capacity measurements for ILs is underestimated, and the possible causes of this were discussed. With the use of the set of 19 ILs for which the reliable heat capacity data and the density data are available, it was found that the quotient of heat capacity at constant pressure to volume for these liquids remains constant within +- 5 % at a given temperature and linearly changes with temperature in the temperature range of (258 to 370) K. It was demonstrated that the selection of an IL for technical applications is limited not by its heat capacity but by the other parameters.

Compounds

#	Formula	Name
1	C7H13BrN2	1-methyl-3-propylimidazolium bromide
2	C10H15N5	1-butyl-3-methylimidazolium dicyanamide
3	C8H16N2O4S	1-ethyl-3-methylimidazolium ethyl sulfate
4	C8H15BF4N2	1-butyl-3-methylimidazolium tetrafluoroborate
5	C9H15F3N2O3S	1-butyl-3-methylimidazolium trifluoromethanesulfonate
6	C12H23BF4N2	1-methyl-3-octylimidazolium tetrafluoroborate
7	C20H35F6N3O4S2	1-tetradecyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide
8	C9H18F6N2O4S2	butyltrimethylammonium bis(trifluoromethylsulfonyl)imide
9	C11H20F6N2O4S2	1-butyl-1-methylpyrrolidinium bis[(trifluoromethyl)sulfonyl]imide

Datasets

The table above is generated from the ThermoML associated json file (link above). POMD and RXND refer to PureOrMixture and Reaction Datasets. The compound numbers are included in properties, variables, and phases, if specificied; the numbers refer to the table of compounds on the left.
Type	Compound-#	Property	Variable	Constraint	Phase	Method	#Points
POMD	1	Molar enthalpy of transition or fusion, kJ/mol ; Crystal			Crystal Liquid Air at 1 atmosphere	Adiabatic calorimetry	1
POMD	1	Triple point temperature, K ; Crystal			Crystal Liquid Gas	ADIACA:UFactor:8	1
POMD	1	Molar heat capacity at constant pressure, J/K/mol ; Liquid	Temperature, K; Liquid	Pressure, kPa; Liquid	Liquid	Vacuum adiabatic calorimetry	72
POMD	1	Mass density, kg/m3 ; Liquid	Temperature, K; Liquid	Pressure, kPa; Liquid	Liquid	Pycnometric method	12
POMD	2	Molar enthalpy of transition or fusion, kJ/mol ; Crystal			Crystal Liquid Air at 1 atmosphere	Adiabatic calorimetry	1
POMD	2	Triple point temperature, K ; Crystal			Crystal Liquid Gas	ADIACA:UFactor:12	1
POMD	2	Molar heat capacity at constant pressure, J/K/mol ; Liquid	Temperature, K; Liquid	Pressure, kPa; Liquid	Liquid	Vacuum adiabatic calorimetry	78
POMD	3	Molar heat capacity at constant pressure, J/K/mol ; Liquid	Temperature, K; Liquid	Pressure, kPa; Liquid	Liquid	Vacuum adiabatic calorimetry	92
POMD	4	Molar heat capacity at constant pressure, J/K/mol ; Liquid	Temperature, K; Liquid	Pressure, kPa; Liquid	Liquid	Vacuum adiabatic calorimetry	79
POMD	5	Molar enthalpy of transition or fusion, kJ/mol ; Crystal			Crystal Liquid Air at 1 atmosphere	Adiabatic calorimetry	1
POMD	5	Triple point temperature, K ; Crystal			Crystal Liquid Gas	ADIACA:UFactor:4	1
POMD	5	Molar heat capacity at constant pressure, J/K/mol ; Liquid	Temperature, K; Liquid	Pressure, kPa; Liquid	Liquid	Vacuum adiabatic calorimetry	39
POMD	6	Molar enthalpy of transition or fusion, kJ/mol ; Crystal			Crystal Liquid Air at 1 atmosphere	Adiabatic calorimetry	1
POMD	6	Triple point temperature, K ; Crystal			Crystal Liquid Gas	ADIACA:UFactor:6	1
POMD	6	Molar heat capacity at constant pressure, J/K/mol ; Liquid	Temperature, K; Liquid	Pressure, kPa; Liquid	Liquid	Vacuum adiabatic calorimetry	107
POMD	7	Molar enthalpy of transition or fusion, kJ/mol ; Crystal			Crystal Liquid Air at 1 atmosphere	Adiabatic calorimetry	1
POMD	7	Triple point temperature, K ; Crystal			Crystal Liquid Gas	ADIACA:UFactor:12	1
POMD	7	Molar heat capacity at constant pressure, J/K/mol ; Liquid	Temperature, K; Liquid	Pressure, kPa; Liquid	Liquid	Vacuum adiabatic calorimetry	50
POMD	8	Molar enthalpy of transition or fusion, kJ/mol ; Crystal			Crystal Liquid Air at 1 atmosphere	Adiabatic calorimetry	1
POMD	8	Triple point temperature, K ; Crystal			Crystal Liquid Gas	ADIACA:UFactor:4	1
POMD	8	Molar heat capacity at constant pressure, J/K/mol ; Liquid	Temperature, K; Liquid	Pressure, kPa; Liquid	Liquid	Vacuum adiabatic calorimetry	48
POMD	9	Molar enthalpy of transition or fusion, kJ/mol ; Crystal			Crystal Liquid Air at 1 atmosphere	Adiabatic calorimetry	1
POMD	9	Triple point temperature, K ; Crystal			Crystal Liquid Gas	ADIACA:UFactor:4	1
POMD	9	Molar heat capacity at constant pressure, J/K/mol ; Liquid	Temperature, K; Liquid	Pressure, kPa; Liquid	Liquid	Vacuum adiabatic calorimetry	72

Thermodynamics Research Center / ThermoML | Journal of Chemical and Engineering Data

Heat Capacity of Ionic Liquids: Experimental Determination and Correlations with Molar Volume

Paulechka, Y. U.[Yauheni U.], Kabo, A. G.[Andrey G.], Blokhin, A. V.[Andrey V.], Kabo, G. J.[Gennady J.], Shevelyova, M. P.[Marina P.]

ABSTRACT