# Chemical Forums

## Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: linkamfai on June 24, 2015, 06:18:50 AM

Title: [Help] Prove that delta G<= 0 for constant T and P
Post by: linkamfai on June 24, 2015, 06:18:50 AM
How to prove that Delta G <= 0 for constant T and P processes,

What is the implication of this inequality?
Title: Re: [Help] Prove that delta G<= 0 for constant T and P
Post by: Dan on June 24, 2015, 06:26:02 AM
You must show you have attempted the question, this is a Forum Rule (http://www.chemicalforums.com/index.php?topic=65859.0).
Title: Re: [Help] Prove that delta G<= 0 for constant T and P
Post by: linkamfai on June 24, 2015, 07:40:18 AM
G=H-TS
H=U+PV
=> G= U+PV-TS

dG=dU+PdV +VdP - TdS - SdT
=> dU = dq+dw ; dw= dw'-PexdV => w' = non-expansion work
=> dG=dw'(max)

deltaG = w'(max)

but i don't know how to show delta G must <=0 for an isolated system, also the meaning for this inequality
Title: entropy and G of fertilied egg
Post by: linkamfai on June 24, 2015, 08:34:51 AM
Consider a fertilized hen egg in and incubator at a constant temperature and pressure environment.

The fertilized egg, hen proteins are formed into a highly ordered chick. Explain why the development of the chick is consistent with the second law. Please include the environment in the discussion.

b) Does the G of the system increase, decrease, or remain the same? How do you know?

ΔSuni=ΔS(sys) + (-ΔHsys/T)
is it because that the process of developing the chick would release heat to the environment?
Title: Re: [Help] Prove that delta G<= 0 for constant T and P
Post by: mjc123 on June 24, 2015, 08:49:35 AM
Consider what you wrote in your other post, about the egg. Can you express that equation slightly differently?
Title: Re: entropy and G of fertilied egg
Post by: Arkcon on June 24, 2015, 05:54:21 PM
What is the definition of each term in the Gibbs free energy equation you've quoted?  Which part of your word problem matches which term in the equation?  Does the development of the chick release heat into the system?  And is that the only thing driving ΔG?
Title: Re: [Help] Prove that delta G<= 0 for constant T and P
Post by: Arkcon on June 24, 2015, 06:01:20 PM
Consider what you wrote in your other post, about the egg. Can you express that equation slightly differently?

So why not merge the posts, and let's have all the work together.  So I did. ;D