Speed of Sound and Adiabatic Compressibility of 1-Ethyl-3-methylimidazolium Bis(trifluoromethylsulfonyl)imide under Pressures up to 100 MPa

J. Chem. Eng. Data, 2013, 58 (6), pp 1571–1576.

Marzena Dzida, Mirosław Chorązewski , Monika Geppert-Rybczyńska , Edward Zorębski , Michał Zorębski , Monika Zarska, Bozena Czech.

Institute of Chemistry, University of Silesia, Szkolna 9, 40-006 Katowice, Poland

 

Abstract

 

 

The speed of ultrasound measurements in 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [EMIm][NTf2], were performed in the temperature range from (288 to 318) K and at pressures from (15 to 101) MPa. The speeds of ultrasound, densities, and isobaric heat capacities have been determined at ambient pressure for temperatures from (287 to 323) K, (278.15 to 363.15) K, and (293.15 to 323.15) K, respectively. The pressure dependence of densities and adiabatic compressibilities were calculated using the speeds of ultrasound at high pressure as well as densities and heat capacities at ambient pressure. The experimental densities reported in the literature are in a good agreement with the densities calculated in this work.

Copyright © 2013 American Chemical Society

 

 

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Additional Information

 

The acoustic method has found wide acceptance as a precise tool for the determination of thermodynamic properties of compressed liquids. This is the one of the most useful, attractive, and  alternative way to the direct determination of the pPT data of liquids. These data obtained from the experimental speeds of sound belong to the most reliable ones because the speed of sound can be measured accurately over wide ranges of temperature and pressure. The speed of sound is connected with other properties, it allows the derivations of a wide range of important physicochemical properties including adiabatic and isothermal compressibilities,  thermal expansivity, isobaric and isochoric heat capacities, internal pressure, nonlinearity parameter B/A, inversion curve of the Joule-Thomson phenomenon, etc.

 

Nowadays, knowledge of the properties of pure ionic liquids and their mixtures with other liquids is essentially important for design and optimization of many chemical processes using ionic liquids as green solvents, heat transfer and heat storage media, hydraulic fluids. When developing ionic liquids as designer-media for sustainable chemistry and given purpose, reliable speed of sound data are one of the prerequisites for an efficient design of ionic liquids with desired properties.

Another very important area of ​​application of speed of sound measurements is the automotive and petrochemical industry. As the fuel injection in an engine is approximately an adiabatic process, the adiabatic compressibility seems to be more useful than the isothermal one in estimation of the fuel injection timing. The accurate knowledge of properties of fuels and especially new generation biofuels is crucial for the design of the engines and injection systems, including modern common rail technology where the pressure can reach up to 250 MPa.

 

Besides, the speed of sound, and ultrasound absorption as ultrasonic spectrometry are useful in investigation of various chemical, biochemical, and physicochemical liquid systems, their structure, molecular dynamics and kinetics. First of all, they give information about the chemical relaxation and related elementary processes like ionic and molecular reaction, proton transfer, hydrogen bonding, structural isomerization, and micelle formation.

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