Gibbs Free Energy and the Grand Potential


by Useful nucleus
Tags: energy, free, gibbs, grand, potential
Useful nucleus
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#1
Aug12-13, 02:41 PM
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Gibbs Free Energy is the appropriate potential when there is both heat exchange and mechanical work (G=E-TS+PV). On the other hand the grand potential is appropriate when there is heat exchange and chemical work (g=E-TS-μN).
Is there any issue in defining a potential of the form (E-TS-μN+PV) such that it is conserved in some ensemble? If there is no problem, is there a consensus on a name for such potential and its corresponding ensemble?
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DrDu
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#2
Aug13-13, 05:34 AM
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The problem is probably that the corresponding potential vanishes identically as G=mu N and g=-PV. You need the potential to depend on at least one extensive variable. If not, you can no longer specify the amount of substance you are talking about.


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