Which is more stable: Fe3O4 or Fe2O3?






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manasa933
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Joined: Fri Sep 29, 2017 7:04 am

Which is more stable: Fe3O4 or Fe2O3?

Postby manasa933 » Sun Feb 11, 2018 8:07 pm

The solutions manual says Fe2O3 is more stable, but since the G of formation is more negative for Fe3O4 , isn't it more stable? Also since Fe3O4 is a larger compound, shouldn't it be more stable?

Emily Mei 1B
Posts: 50
Joined: Fri Sep 29, 2017 7:04 am

Re: Which is more stable: Fe3O4 or Fe2O3?

Postby Emily Mei 1B » Sun Feb 11, 2018 8:29 pm

Not sure what you mean by "stable", but larger compounds are typically heavier, which means they'd have a larger degeneracy and therefore more entropy. So Fe3O4 should have a higher entropy.

Elizabeth Ignacio 1C
Posts: 39
Joined: Fri Sep 29, 2017 7:07 am

Re: Which is more stable: Fe3O4 or Fe2O3?

Postby Elizabeth Ignacio 1C » Sun Feb 11, 2018 10:28 pm

I believe the stability of Fe3O4 and Fe2O3 were mentioned in problem 9.81, and in that problem, it was important to write out the equation that involves the two of them, which is 4Fe3O4 + O2 -> 6Fe2O3. This Gibbs Free Energy for this forward reaction is negative and the reverse is positive, which means that the reaction that forms Fe2O3 is favorable and Fe2O3 is more stable.


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