How does partial pressure affect Gibbs free energy?

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Answer 1 · 2015-12-17T22:16:36

#DeltaG=DeltaG^@+RTln(((P_(NH_3))^2)/((P_(N_2))(P_(H_2))^3))#

Consider the following reaction:

#N_2(g) +3H_2(g) rightleftharpoons 2NH_3(g)#

The free energy of this equilibrium could be found by the following expression:

#DeltaG=DeltaG^@+RTlnK#

where #K# is the equilibrium constant that is given by:

#K=((P_(NH_3))^2)/((P_(N_2))(P_(H_2))^3)#

Therefore, the Gibbs free energy is related to the partial pressure by:

#DeltaG=DeltaG^@+RTln(((P_(NH_3))^2)/((P_(N_2))(P_(H_2))^3))#

Here is a video that explains the origin on this expression in details:

Thermodynamics | Free Energy, Pressure & Equilibrium.