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Topic: Relationship Between Gibbs Energy, pressure, help please!  (Read 4031 times)

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Offline Roger

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Relationship Between Gibbs Energy, pressure, help please!
« on: December 04, 2007, 09:01:24 PM »
Given reaction Gibbs energy, ΔrG, for a specified temperature, how can I find the total pressure of the reaction that had to be used to get this value of ΔrG?
 
I am given the chemical reaction, and can compute, if necessary, ΔrGθ, ΔrHθ, and ΔrSθ. What are the steps I need to take to compute the total reaction pressure, what is the relationship between ΔrG and total reaction pressure? Thanks very much.

Offline Hunt

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Re: Relationship Between Gibbs Energy, pressure, help please!
« Reply #1 on: December 08, 2007, 01:04:25 PM »
I think you're still trying to solve that ammonia synthesis problem you posted earlier , aren't you ? There is a way to establish delta G^o as a function of the total pressure. This isn't what you need though .

e^{-deltaG^o/RT} = K_x / P^2 ( where the standard pressure = 1 bar ... )

K_x = eq mol fractions of species
P = total pressure

For your previous problem you need to look at the graphs given to you inorder to find the total pressure at a specific temp.

The problem states , "Isotherms of ΔrG(T, p) in the pressure range 100atm <= p <= 400atm are needed to derive the answer."


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