CHAPTER 4 – The Thermodynamics of Irreversible Processes

TLDR: The theory of transformations is a description of a particular class of irreversible processes and may appropriately be described as kinetic as discussed by the authors, which is a connection between the microscopic properties of the systems of the assembly and the macroscopic (measurable) properties is made by statistical mechanics.

Abstract: Classical thermodynamics is concerned primarily with the interdependence of certain well-defined macroscopic concepts (temperature, pressure, entropy, energy, composition, etc.) possessed by a closed assembly. The usual thermodynamic equations are valid only for assemblies at equilibrium and for reversible transitions among such equilibrated assemblies. When thermodynamic considerations are applied to irreversible (i.e. “natural”) processes, the equations become inequalities, and are much less useful. For example, the principle of increase in entropy during an adiabatic irreversible process provides information only about the direction of the change. The theory of transformations is a description of a particular class of irreversible processes. This type of theory is the main concern of this chapter and may appropriately be described as kinetic. The connection between the microscopic properties of the systems of the assembly and the macroscopic (measurable) properties is made by statistical mechanics. The thermodynamics of irreversible processes has also been applied to chemical reactions, though only in the limiting case of very close approach to equilibrium.