Editing Equation of state (section)

{{Short description|Equation describing a state of matter under a given set of conditions}}
{{About||the use of this in cosmology|Equation of state (cosmology)| the use of this concept in optimal control theory|Optimal control#General method}}

In [[physics]] and [[chemistry]], an '''equation of state''' is a [[thermodynamic equations|thermodynamic equation]] relating [[state variable]]s, which describe the state of matter under a given set of physical conditions, such as [[pressure]], [[Volume (thermodynamics)|volume]], [[temperature]], or [[internal energy]].<ref name="Perrot" >{{cite book | author=Perrot, Pierre | title=A to Z of Thermodynamics | publisher=Oxford University Press | year=1998 | isbn=978-0-19-856552-9}}</ref><ref>{{Cite book |last=Eliezer |first=S. |title=An Introduction to Equation of State: Theory and Applications |last2=Gahatak |first2=A. |last3=Hora |first3=H. |author-link3=Heinrich_Hora |publisher=Cambridge University Press |year=1986 |isbn=0521303893}}</ref> Most modern equations of state are formulated in the [[Helmholtz free energy]]. Equations of state are useful in describing the properties of pure substances and mixtures in liquids, gases, and [[solid]] states as well as the state of matter in the interior of [[star]]s.<ref>{{Cite book |last=Horedt |first=G.P. |title=Polytropes. Applications in Astrophysics and Related Fields |publisher=Dordrecht: Kluwer |year=2004 |isbn=1-4020-2350-2}}</ref> Though there are many equations of state, none accurately predicts properties of substances under all conditions. The quest for a universal equation of state has spanned three centuries.<ref>{{cite journal |last1=Kontogeorgis |first1=Georgios M. |last2=Liang |first2=Xiaodong |last3=Arya |first3=Alay |last4=Tsivintzelis |first4=Ioannis |title=Equations of state in three centuries. Are we closer to arriving to a single model for all applications? |journal=Chemical Engineering Science: X |date=May 2020 |volume=7 |pages=100060 |doi=10.1016/j.cesx.2020.100060|doi-access=free }}</ref>      
{{Thermodynamics|cTopic=[[Thermodynamic system|Systems]]}}
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