Burgot J.-L. The Notion of Activity in Chemistry

Springer International Publishing, Switzerland, 2017. — 607 p. — ISBN: 9783319463995This book is, before all, an attempt to demystify the notion of activity. Activity is interesting and intriguing for chemists, physicists, and others and has been for more than a century. Outside of the physical sciences, it remains often ignored, even unknown.
The notion of activity originates from the application of the basic principles and methods of thermodynamics to chemical processes. It proves to be particularly useful when this application encounters some difficulties. Its introduction permitted the study of the thermodynamic behavior of imperfect gases and nonideal solutions. The particular behavior of systems in both cases is related to the occurrence of mutual non-negligible interactions between molecules of gases or of solutes. It is now well established that handling the intimately linked concepts of activity and fugacity permits one to neatly take into account these interactions. With their introduction, the chemical potentials of imperfect gases and those of the components of nonideal solutions can be expressed in a useful manner in order to study different processes, despite the already mentioned difficulties. This is an important point. Change of the chemical potential of a substance during a physical or a chemical process, indeed, determines its result and its term, which is not a kinetic one. This is the reason why chemical potentials must be expressed in the most realistic way possible.