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Topic: This problem is driving me insane. Can anyone point me in the right direction?  (Read 3160 times)

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Offline Electrolize

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Calculate Kp for the reaction:
N2O4 (g) -> 2NO2 (g)
at 24°C, given that ΔG° = 329.83 J/mole N2O4.

Offline Jorriss

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You can get Kp in terms of Kc and Kc in terms of Gibbs free energy, maybe?

Offline Electrolize

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You can get Kp in terms of Kc and Kc in terms of Gibbs free energy, maybe?

I thought that too but the problem is that, what is given is ΔG° = 329.83 J/mole N2O4 for the half-reaction and not the overall, so it doesn't work...

Offline jsrozner

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 :delta:G =  :delta:Go + RTlnK

I'm pretty sure you can consider Kc to = Kp
in which case you just substitute the values in, taking care to use 240C = 297K.

and its at equilbrium so  :delta:G = 0.

I thought that too but the problem is that, what is given is ΔG° = 329.83 J/mole N2O4 for the half-reaction and not the overall, so it doesn't work...

I don't really understand what you're trying to say, but really the given info means that for every time the reaction occurs (for every mole of N2O4 consumed) the standard change in free energy is 329.83 J. It's not for a half reaction. I'm fairly certain this is just a straightforward plug into the equation.
« Last Edit: July 26, 2010, 12:06:03 AM by jsrozner »

Offline Electrolize

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:delta:G =  :delta:G0 + RTlnK

I'm pretty sure you can consider Kc to = Kp
in which case you just substitute the values in, taking care to use 240C = 297K.

and its at equilbrium so  :delta:G = 0.

I thought that too but the problem is that, what is given is ΔG° = 329.83 J/mole N2O4 for the half-reaction and not the overall, so it doesn't work...

I don't really understand what you're trying to say, but really the given info means that for every time the reaction occurs (for every mole of N2O4 consumed) the standard change in free energy is 329.83 J. It's not for a half reaction. I'm fairly certain this is just a straightforward plug into the equation.


Ok so I have come to the same conclusion. Thank you for chiming in.

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