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Homework Help: Thermodynamic Entropy question

  1. Apr 9, 2010 #1
    1. The problem statement, all variables and given/known data

    The Gibbs free energy of benzene decreases continuously with temperature (at fixed pressure) and shows three nearly linear segments corresponding to the solid, liquid and gas phases. The magnitude of the slopes increases as one moves from solid to liquid, and liquid to gas.
    Use the formula (dG/dT)P = −S to show that S(gas) > S(liquid) > S(solid).

    2. Relevant equations

    (dG/dT)_P = −S

    3. The attempt at a solution
    I have no idea where to begin sadly =\... I made a graph of G vs T, but i dont think that helps much.
  2. jcsd
  3. Apr 9, 2010 #2


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    Draw tangent lines in the solid, liquid, and gas regions. Are the slopes positive or negative, and how do the magnitudes compare?
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