Why does iron corrode in water?

[SamuelTesla]

---

Members do not see this ad.

Iron has an oxidation potential of 0.447
Water has a reduction potential of -0.83

The total is a negative number - so how does a piece of iron corrode when placed in water??? thx

 

[startswithb]

While you are correct that the oxidation potential for water would be higher than iron, you need to consider that redox is about the individual ions instead of the whole molecules. Iron goes from the Fe2+ to Fe3+ and is therefore oxidized. The oxygen is reduced, not the whole water molecule. I would see if you can find the whole corrosion equation written out somewhere. That would probably help you visualize the process better. 🙂