Thermochemistry and Molecular Energetics

Thermochemistry has been defined in one of the most popular physical chemistry textbooks as the study of the heat produced or required by chemical reactions [1], The use of heat, instead of the more general word energy, immediately suggests a close association between thermochemistry and calorimetry—the oldest experimental technique for investigating the thermodynamics of chemical reactions. This view is, in fact, shared by many of our students and some of their teachers, together with the belief that thermochemistry, founded in the eighteenth century by Black, Lavoisier, and Laplace, has seen few major developments since the days of Berthelot and Thomsen, over 100 years ago [2], 

The word energetics, rather than thermochemistry, was adopted in figure 1.2 and in the book title to emphasize that most of the methods displayed do not involve the experimental determination of heat. Furthermore, the use of energetics avoids the traditional link between thermochemistry and calorimetry (which is semantically correct because thermo is the Greek designation for heat ). The word molecular, on the other hand, stresses that this book will be mainly concerned with single molecules. Properties like enthalpies of phase transition, which depend on intermolecular interactions, are very important data in their own right, but the methods used to derive them will not be comprehensively covered. 

To keep this volume within a reasonable size and, at the same time, ensure that each one of the thermochemical methods covered would be described with appropriate detail, we have decided not to include gas-phase and quantum chemistry methods. These have been extensively reviewed in recent publications [9-12]. 

---