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Topic: At equilibrium, but delta G doesn't = 0??  (Read 5356 times)

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Offline Sophia7X

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At equilibrium, but delta G doesn't = 0??
« on: August 04, 2012, 11:50:04 PM »
A reaction is at equilibrium in a closed rigid vessel at constant T when...

ΔS = 0
ΔH = 0
ΔU = 0
ΔG = 0
ΔA = 0

I thought it was ΔG = 0, but it's supposed to be ΔA = 0. What is ΔA anyway? I tried googling but couldn't find what it was.
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Offline Jorriss

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Re: At equilibrium, but delta G doesn't = 0??
« Reply #1 on: August 05, 2012, 12:55:40 AM »
deltaG=0 is the equilibrium condition at constant T and P.

In a sealed rigid container, though, the system is not at constant P so instead one must use the Helmholtz free energy, A. At constant T and V the equilibrium condition is that deltaA=0.

G=E+pV-TS and A=E-TS
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Offline Sophia7X

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Re: At equilibrium, but delta G doesn't = 0??
« Reply #2 on: August 05, 2012, 03:23:13 PM »
Thanks
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