## 9.81

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

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

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

Ana Ordonez 1G
Posts: 13
Joined: Fri Jun 17, 2016 11:28 am

### 9.81

Which is the thermodynamically more stable iron oxide in air, Fe3O4(s) or Fe2O3(s)? Justify your selection.
In the solution, they wrote the chemical equation 4Fe3O4(s)+O2(g)-> 6Fe2O3(s). How would I know based on this problem that I would have to do this?

Jingyuan_Fu_3E
Posts: 8
Joined: Wed Sep 21, 2016 2:59 pm

### Re: 9.81

Hello,

First of all, based on the two chemicals Fe3O4 and Fe2O3, I think you need to figure out a chemical reaction to link these two chemicals together and transvert one into another. The oxidation reaction 4Fe3O4(s)+O2(g)-->6Fe2O3(s) should be the easiest to think of. Then it can be possible to calculate the Gibbs Free Energy of this reaction and see if this reaction is spontaneous or not. Not sure if this is the answer you want.