Editing Thermodynamics (section)

== Potentials ==
[[Thermodynamic potential]]s are different quantitative measures of the stored energy in a system. Potentials are used to measure the 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. Thermodynamic potentials cannot be measured in laboratories, but can be computed using molecular thermodynamics.<ref>{{Cite journal |last1=Graben |first1=H.W. |last2=Ray |first2=John R. |date=1993-12-10 |title=Eight physical systems of thermodynamics, statistical mechanics, and computer simulations |url=http://dx.doi.org/10.1080/00268979300102971 |journal=Molecular Physics |volume=80 |issue=5 |pages=1183–1193 |doi=10.1080/00268979300102971 |bibcode=1993MolPh..80.1183G |issn=0026-8976}}</ref><ref>{{Cite journal |last1=Nitzke |first1=Isabel |last2=Stephan |first2=Simon |last3=Vrabec |first3=Jadran |date=2024-06-03 |title=Topology of thermodynamic potentials using physical models: Helmholtz, Gibbs, Grand, and Null |url=http://dx.doi.org/10.1063/5.0207592 |journal=The Journal of Chemical Physics |volume=160 |issue=21 |doi=10.1063/5.0207592 |pmid=38828811 |bibcode=2024JChPh.160u4104N |issn=0021-9606}}</ref>

The five most well known potentials are:
{{table of thermodynamic potentials}}

where <math>T</math> is the [[thermodynamic temperature|temperature]], <math>S</math> the [[entropy]], <math>p</math> the [[pressure]], <math>V</math> the [[Volume (thermodynamics)|volume]], <math>\mu</math> the [[chemical potential]], <math>N</math> the number of particles in the system, and <math>i</math> 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]].