Thermodynamic Potentials. Essentials Overview

The concept of thermodynamic potentials is explained. The most important potentials are then derived carefully operating on functions expressing thermodynamic quantities as functions of various pairs of independent variables. The demonstrated potentials are Helmholtz energy, Gibbs energy, internal energy, and enthalpy. Reciprocal relations and their practical significance are mentioned, as well as links between Helmholtz energy and work or between enthalpy or internal energy and heat. The whole structure of classical (equilibrium) thermodynamics can be constructed on the basis of several fundamental principles—axioms rooted in experience with thermal behaviour. The principles are summarized in the last section.