Density, Speed of Sound, and Derived Thermodynamic Properties of Ionic Liquids over an Extended Pressure Range. 4. [C3mim][NTf2] and [C5mim][NTf2]
文摘
The current study focuses on 1-propyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide, [C3mim][NTf2],and 1-pentyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide, [C5mim][NTf2]. The objective is to studythe influence of pressure as well as that of the cation's alkyl chain length on several properties of this type ofionic liquids. Speed of propagation of ultrasound waves and densities in pure ionic liquids as a function oftemperature and pressure have been determined. Other thermodynamic properties such as compressibilities andexpansivities have been obtained. Speed of sound measurements have been carried out in broad ranges oftemperature (298 < T/K < 338) and pressure (0.1 < p/MPa < 200). A novel high-pressure ultrasonic cell wasdesigned and built to allow for precise speed of sound measurements in liquids. The uncertainty of the speed ofsound measurements is 0.05 %. A detailed description of the cell is presented. Density measurements have beenperformed over a broad range of temperature (298 < T/K < 333) and pressure (0.1 < p/MPa < 60) using avibrating-tube densimeter. The density overall uncertainty is 0.02 %.