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Topic: Gibbs vs Helmholtz free energy question  (Read 2617 times)

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Offline mnickel5c

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Gibbs vs Helmholtz free energy question
« on: November 30, 2013, 11:02:52 PM »
For reactions in the cell, such as a glycolysis reaction, is there any difference between gibbs and helmholtz free energy?

The difference between the two is pV work and i dont understand how it applies to my problem.

THe question asks to calculate helmholtz free energy. Knowing gibbs free energy, entropy change and enthalpy

Offline Radu

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Re: Gibbs vs Helmholtz free energy question
« Reply #1 on: January 05, 2014, 05:37:04 PM »
  yes, there is a difference, the gibbs energy represents the maximum non-expansion work, while the Helmholtz energy represents the maximum available work. A cell can use only the gibbs free energy, then, given its internal volume stays the same. 
     I think the problem wants to see how well we could drive energy out by expansion work (dA) and , by comparison, how well the cells use the chemical energy(dG)
  So, from the reaction entropy, enthalpy and gibbs energy you find the temperature( quite odd), and then you write dA=dU-TdS=-TdS, because the temperature inside the cell is constant, so ΔA is straightforward.

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