## 4.41 (7th edition)

$\Delta G^{\circ}= \Delta H^{\circ} - T \Delta S^{\circ}$

$\Delta G^{\circ}= -RT\ln K$

$\Delta G^{\circ}= \sum \Delta G_{f}^{\circ}(products) - \sum \Delta G_{f}^{\circ}(reactants)$

Andie Jian 1D
Posts: 69
Joined: Fri Sep 28, 2018 12:17 am
Been upvoted: 1 time

### 4.41 (7th edition)

When comparing whether Fe3O4 or Fe2O3 is more stable based on their free energy, why do we have to find the standard gibb's free energy of the reaction of Fe3O4 and O2 into Fe2O3 in order to determine this, rather than just comparing each of their individual free energies?

armintaheri
Posts: 68
Joined: Fri Sep 28, 2018 12:26 am

### Re: 4.41 (7th edition)

I think you can look at the individual free energies. The one with a smaller G will be the more stable one. But a negative $\Delta G$ for the reaction tells you the same thing so you could just look at that instead of looking at two numbers. I can't think of any reason why you wouldn't get the same result either way.