Isobaric and Isochoric Heat Capacities of Imidazolium-Based and Pyrrolidinium-Based Ionic Liquids as a Function of Temperature: Modeling of Isobaric Heat Capacity

Abstract

The isobaric and isochoric heat capacities of seven 1-alkyl-3-methylimidazolium bis­(trifluoromethylsulfonyl)­imides, two 1-alkyl-1-methylpyrrolidinium bis­(trifluoromethylsulfonyl)­imides, and two bis­(1-alkyl-3-methylimidazolium) tetrathiocyanatocobaltates were determined at atmospheric pressure in the temperature range from 293.15 to 323.15 K. The isobaric heat capacities were determined by means of differential scanning calorimetry, whereas isochoric heat capacities were determined along with isothermal compressibilities indirectly by means of the acoustic method from the speed of sound and density measurements. Based on the experimental data, as expected, the isobaric heat capacity increases linearly with increasing alkyl chain length in the cation of 1-alkyl-3-methylimidazolium bis­(trifluoromethylsulfonyl)­imides and no odd and even carbon number effect is observed. After critical comparison of the obtained data with the available literature data, the most reliable values are recommended. It has been also shown that, although the COSMOthermX calculations underestimated the isobaric heat capacity values whatever the temperature and the ionic liquid structure, the approach used during this work may be applied to estimate physical properties of non-single-charged ions as well. Additionally, based on the speeds of sound the thermal conductivities were calculated using a modified Bridgman relation.

High Pressure Speed of Sound and Related Thermodynamic Properties of 1-Alkyl-3-methylimidazolium Bis[(trifluoromethyl)sulfonyl]imides (from 1-Propyl- to 1-Hexyl-)

“…7, 45 Calculated densities and isobaric heat capacities at high-pressure are reported in Tables 5 and 6, respectively.…”

Remarkable Thermal Conductivity Enhancement in Carbon-Based Ionanofluids: Effect of Nanoparticle Morphology

“…Isobaric heat capacity data of 1-butanol reported by Zorȩbski and Góralski 47 were used as reference values. The apparatus was tested using n -hexane and benzene as described in ref ( 48 ). Based on the calibration procedure, test runs, measurement procedure, sample property, temperature measurement uncertainty, and neglecting vapor correction, the expanded uncertainty (coverage factor 2.0, confidence level 0.95) of the isobaric heat capacity obtained in this work was estimated to be of ±2%.…”

Further development of the predictive models for physical properties of pure ionic liquids: Thermal conductivity and heat capacity

“…Many models, based on group contribution methods, artificial neural networks, or genetic algorithm, have been proposed for the predictions of the ILs thermal conductivity, to date [10,11,13,15,16,18,20,25,31]. It is worth noting that the terms 'correlative' and 'predictive' are often wrongly used in a interchangeably manner.…”