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Topic: Problem with calculation of Gibbs free energy  (Read 3890 times)

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Offline diablo

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Problem with calculation of Gibbs free energy
« on: December 14, 2009, 03:01:12 PM »
Hi folks,

can anyone please help me find a way to calculate this :

calculate the change of gibbs free energy at 337.8K ( boiling point of Methanol at 1.013bar) for following reactions

1)CH3OH(l)--> CH3OH(l) at p= 0.9bar
2)CH3OH(l)--> CH3OH(l) at p= 1.013 bar
3)CH3OH(l)--> CH3OH(l) at p= 1.100bar

Solution: -332.18kJ/mol, 0kJ/mol, 231.4kJ/mol

I dont have any idea what formula i should use... --> do i need additional values to solve this calculation?


Offline diablo

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Re: Problem with calculation of Gibbs free energy
« Reply #1 on: December 14, 2009, 06:05:01 PM »
i think i've got it, but still im not sure:

obviousely it got something to do with the chemical potential:

µ = G  (for pure substance)

µ = µ0+RTln(p/p0)

if i assume µ0= 0 , i get the right solution...

but still i dont understand why i can assue µ0 as zero..


Offline plankk

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Re: Problem with calculation of Gibbs free energy
« Reply #2 on: December 15, 2009, 05:51:13 AM »
In task you have to calculate "the change". So you can assume that G00 and Ge0+RTln(p/p0) so  :delta: G=Ge-G0=RTln(p/p0)

Offline diablo

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Re: Problem with calculation of Gibbs free energy
« Reply #3 on: December 15, 2009, 08:34:30 AM »
In task you have to calculate "the change". So you can assume that G00 and Ge0+RTln(p/p0) so  :delta: G=Ge-G0=RTln(p/p0)

 :D , thx alot for your answer !

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