The range and scope of thermodynamics is implied in Wigner's epigrammatic quote above, except for the fact that there are a great many phenomena for which thermodynamics can provide quite accurate calculations. Chemical engineering is to a large extent based on thermodynamic calculations applied to practical systems. The phase rule is indispensable to metallurgists, geologists, geochemists, crystallographers, mineralogists, and chemical engineers. Although students sometimes come away with the notion that thermodynamics is remote and abstract, it is actually the most practical of subjects. Part of what we endeavor to do in this book is to illustrate that practicality, the tie to everyday life and utility.

Thermodynamics comprises a field of knowledge that is fundamental and applicable to a vast area of human experience. It is a study of the interactions between two or more bodies, the interactions being described in terms of the basic concepts of heat and work. These concepts are deduced from experience, and it is this experience that leads to statements of the first and second laws of thermodynamics. The first law leads to the definition of the energy function, and the second law leads to the definition of the entropy function. With the experimental establishment of these laws, thermodynamics gives an elegant and exact method of studying and determining the properties of natural systems.