This section is about using Gibb’s free energy to do calculations involving equilibria, so make sure you’re comfortable with this first!
Gibb’s free energy of A, GA, is:
For the whole reaction, the total change in G is:
In line 3, we assume n = 1. In line 4, we combine the partial pressures using the rules of logs.
At equilibrium ΔG is zero, which gives:
This is a very important equation. It has another form:
Combining this with another equation for Gibb’s free energy:
and this can be plotted on a graph.
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