Question

When `FeO` is oxidized further to `Fe_2O_3`, is the reaction exothermic?

Answer 1

You are making bonds, so my guess is that heat is evolved.

Explanation:

As physical scientists, we should seek numerical data for the thermodynamics of the oxidation of `Fe(II)`:

`4FeO(s) + O_2(g) rarr 2Fe_2O_3(s) + Delta`

Because bonds are MADE when `Fe(II)` is oxidized we predict that the reaction as written is exothermic.

You would be surprised to learn of the amount of money spent each year on corrosion protection. Every bridge, every skyscraper fights a losing battle against corrosion. Vast teams of corrosion engineers would be vetting steel structures worldwide. They all doomed to fall down (but hopefully not in the next 500 years).