Second law of thermodynamics: Difference between revisions

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m (New page: For a reversible change :<math>dQ=TdS</math> Thus for a closed system (<math>n</math> fixed): :<math>dU=TdS -PdV</math> For an open system: :<math>dU=TdS -PdV + \mu dN</math> For <ma...)
 
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For a reversible change
For a reversible change
:<math>dQ=TdS</math>
:<math>\left.dQ\right.=TdS</math>


Thus for a closed system (<math>n</math> fixed):
Thus for a closed system (<math>n</math> fixed):


:<math>dU=TdS -PdV</math>
:<math>\left.dU\right.=TdS -PdV</math>


For an open system:
For an open system:


:<math>dU=TdS -PdV + \mu dN</math>
:<math>\left.dU\right.=TdS -PdV + \mu dN</math>


For  <math>U(S,V)</math> one has the following total differential
For  <math>U(S,V)</math> one has the following total differential


:<math>dU=\left(\frac{\partial U}{\partial S}\right)_V dS + \left(\frac{\partial U}{\partial V}\right)_S dV</math>
:<math>dU=\left(\frac{\partial U}{\partial S}\right)_V dS + \left(\frac{\partial U}{\partial V}\right)_S dV</math>

Revision as of 18:05, 22 February 2007

For a reversible change

Thus for a closed system ( fixed):

For an open system:

For one has the following total differential