Potentials
In what way are potentials used?
Thermodynamics
Thermodynamic potentials are different quantitative measures of the stored energy in a system. Potentials are used to measure energy changes in systems as they evolve from an initial state to a final state. The potential used depends on the constraints of the system, such as constant temperature or pressure. For example, the Helmholtz and Gibbs energies are the energies available in a system to do useful work when the temperature and volume or the pressure and temperature are fixed, respectively. The five most well known potentials are:where formula_1 is the temperature, formula_2 the entropy, formula_3 the pressure, formula_4 the volume, formula_5 the chemical potential, formula_6 the number of particles in the system, and formula_7 is the count of particles types in the system. Thermodynamic potentials can be derived from the energy balance equation applied to a thermodynamic system. Other thermodynamic potentials can also be obtained through Legendre transformation.