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Difference between revisions of "Phase equilibrium diagram"

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The projection onto the plane of two arbitrary thermodynamical variables of those regions of the surface of the equilibrium states in the space of the complete family of thermodynamical variables that correspond to <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/p/p072/p072560/p0725601.png" />-phase states, <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/p/p072/p072560/p0725602.png" />, of the thermodynamical system. In the case of a one-component system the regions of this surface are cylindrical surfaces and they project onto the <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/p/p072/p072560/p0725603.png" />-plane (pressure-temperature plane) in the form of a curve, the general form of its equation — equality of the chemical potentials of different phases, <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/p/p072/p072560/p0725604.png" /> — can in the case of phase transition of the first kind be written in the form of the Clapeyron–Clausius equation
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The projection onto the plane of two arbitrary thermodynamical variables of those regions of the surface of the equilibrium states in the space of the complete family of thermodynamical variables that correspond to $n$-phase states, $n\geq2$, of the thermodynamical system. In the case of a one-component system the regions of this surface are cylindrical surfaces and they project onto the $(p,T)$-plane (pressure-temperature plane) in the form of a curve, the general form of its equation — equality of the chemical potentials of different phases, $\mu_1(p,T)=\mu_2(p,T)$ — can in the case of phase transition of the first kind be written in the form of the Clapeyron–Clausius equation
  
<table class="eq" style="width:100%;"> <tr><td valign="top" style="width:94%;text-align:center;"><img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/p/p072/p072560/p0725605.png" /></td> </tr></table>
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$$\frac{dP}{dT}=\frac{L}{T(v_1-v_2)},$$
  
where <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/p/p072/p072560/p0725606.png" /> is the latent heat of the transition, and <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/p/p072/p072560/p0725607.png" /> and <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/p/p072/p072560/p0725608.png" /> are the specific volumes for the first and the second phases. A three-phase state is represented by a point, called a triple point.
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where $L$ is the latent heat of the transition, and $v_1$ and $v_2$ are the specific volumes for the first and the second phases. A three-phase state is represented by a point, called a triple point.
  
 
====References====
 
====References====

Latest revision as of 17:50, 5 August 2014

The projection onto the plane of two arbitrary thermodynamical variables of those regions of the surface of the equilibrium states in the space of the complete family of thermodynamical variables that correspond to $n$-phase states, $n\geq2$, of the thermodynamical system. In the case of a one-component system the regions of this surface are cylindrical surfaces and they project onto the $(p,T)$-plane (pressure-temperature plane) in the form of a curve, the general form of its equation — equality of the chemical potentials of different phases, $\mu_1(p,T)=\mu_2(p,T)$ — can in the case of phase transition of the first kind be written in the form of the Clapeyron–Clausius equation

$$\frac{dP}{dT}=\frac{L}{T(v_1-v_2)},$$

where $L$ is the latent heat of the transition, and $v_1$ and $v_2$ are the specific volumes for the first and the second phases. A three-phase state is represented by a point, called a triple point.

References

[1] R. Kubo, "Thermodynamics" , North-Holland (1968)


Comments

References

[a1] L.D. Landau, E.M. Lifshitz, "Statistical physics" , 1 , Pergamon (1980) (Translated from Russian)
[a2] E. Fermi, "Thermodynamics" , Dover, reprint (1956)
How to Cite This Entry:
Phase equilibrium diagram. Encyclopedia of Mathematics. URL: http://encyclopediaofmath.org/index.php?title=Phase_equilibrium_diagram&oldid=11670
This article was adapted from an original article by I.A. Kvasnikov (originator), which appeared in Encyclopedia of Mathematics - ISBN 1402006098. See original article