## Which is more stable, Fe3O4 or Fe2O3?

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

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

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

jenshan
Posts: 23
Joined: Wed Nov 18, 2015 3:00 am

### Which is more stable, Fe3O4 or Fe2O3?

I don't understand the answer keys reasoning: Fe2O3 is thermodynamically more stable, because Gr for the interconversion from Fe3O4 to Fe2O3 is negative. delta G for Fe3O4 is more negative than Fe2O3, shouldn't that mean that it is more thermodynamically stable?

Shaye Busse 3B
Posts: 20
Joined: Fri Sep 25, 2015 3:00 am

### Re: Which is more stable, Fe3O4 or Fe2O3?

The reason for this comes when looking at what G stands for. G is a measure of Gibbs Free Energy, or a measure involving the changes of heat and entropy in relation to temperature. When there is no change in heat or entropy, or in the most stable state possible, the delta G is equal to 0. The reason the answer is the one with a G closest to zero is because a G value of zero is most stable.