Thermophysical properties of ionic liquids: Do we know how to measure them accurately?

Low temperature ionic liquids (LTILs) are innovative fluids for chemical and materials processing, and the recent explosion on their measurement, molecular interpretations and property prediction, allied to the first industrial processes that start to use them as environmentally friendly solvents and reaction fluids, raises a very important point to all the scientific and industrial community, for those that have been involved in the measurement of thermophysical properties of liquids. A careful analysis, assessing its quality, shows that there are discrepancies between data from different laboratories, and sometimes, from samples of different synthesis batches. Therefore a fundamental question must be raised: Do we know enough about the molecular constitution and properties of these fluids, to measure correctly their properties? And if we think we know, which types of care have we to take a priori? It is the purpose of this paper to analyze the main problems in the measurement of some thermophysical properties of RTILs (density, heat capacity; viscosity, thermal conductivity, and electrical conductivity), calling the attention to the uses and misuses of traditional equipment, with or without handling care. (C) 2010 Elsevier BM. All rights reserved.