Critical variable: Difference between revisions

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'''Critical variables''' are defined, for example in [[Physics:Thermodynamics|thermodynamics]], in terms of the values of variables at the critical point.  
{{Short description|Thermodynamic variables associated with critical points}}
'''Critical variables''' are defined, for example in [[Physics:Thermodynamics|thermodynamics]], in terms of the values of variables at the [[Critical point|critical point]].  


On a PV diagram, the critical point is an [[Inflection point|inflection point]]. Thus:  
On a PV diagram, the critical point is an [[Inflection point|inflection point]]. Thus:<ref name=Sommerfeld >{{cite book | last = Sommerfeld | first = A. | editor-last1 = Bopp | editor-first1 = F. | editor-last2 = Meixner | editor-first2 = J. | translator-last = Kestin | translator-first = J. | date = 1956 | title = Thermodynamics and Statistical Mechanics - Lectures on Theoretical Physics Volume V | location = NY | publisher = Academic Press | pages=56-57}}</ref>


:<math>
:<math>
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</math>
</math>


For the [[Physics:Van der Waals equation|van der Waals equation]], the above yields:  
For the [[Physics:Van der Waals equation|van der Waals equation]], the above yields:<ref name=Sommerfeld/>


:<math>
:<math>
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==References==
{{reflist}}
{{DEFAULTSORT:Critical Variable}}
{{DEFAULTSORT:Critical Variable}}
[[Category:Thermodynamic properties]]
[[Category:Thermodynamic properties]]
[[Category:Conformal field theory]]
[[Category:Conformal field theory]]


{{Unreferenced|date=2021}}
{{Sourceattribution|Critical variable}}
{{Sourceattribution|Critical variable}}

Latest revision as of 19:14, 22 May 2026

Short description: Thermodynamic variables associated with critical points

Critical variables are defined, for example in thermodynamics, in terms of the values of variables at the critical point.

On a PV diagram, the critical point is an inflection point. Thus:[1]

(PV)C=0
(2PV2)C=0

For the van der Waals equation, the above yields:[1]

PC=a27b2
VC=3nb
TC=8a27bR

References

  1. 1.0 1.1 Sommerfeld, A. (1956). Thermodynamics and Statistical Mechanics - Lectures on Theoretical Physics Volume V. NY: Academic Press. pp. 56-57.