Oxygen as fuel

Thank you all for your replies. It’s been very enlightening. I had decided not to post any more replies in here because I didn’t want to bump it back up, but since it is now back on page one I just wanted to say thanks.

And, while we have an oxidation free-for-all here, iron `burns’ in a rather undramatic way to form flakes of ferric oxide (or ferrous oxide, it’s been a while), aka rust. It releases heat, but it’s so slow you don’t notice it, and there isn’t a flame, but it is oxidation. That means the iron atoms are losing electrons to the oxygen atoms coming out of the air to form the oxide.

Each oxygen atom wants two electrons to complete its outer shell, so it will gladly enter into compounds such as H[sub]2[/sub]O (water) and O[sub]2[/sub] (diatomic oxygen, commonly found on earth as a gas in the atmosphere). Iron happens to have electrons pretty much floating around free in its solid form (the electron soup model for metals explains things like conductivity and ready oxidation), so oxygen atoms will glom onto iron atoms, which donate electrons pretty easily. Of course, nature abhors a free charged particle, so magnetism makes the oxygen and iron atoms stick together.

There’s a handy little acronym for this process: Oil Rig. It means `Oxidation Is Loss, Reduction Is Gain,’ from the fact that when the iron atom in the example above was oxidised, it lost electrons, and when the oxygen atom gained electrons, its charge was reduced (an electron carries a charge of -1).

[nitpick]I think the term ‘rust’ usually refers to Iron Hydroxide.[/nitpick]

So, it then follows most logically that if you want to try to make a truly sealed room for when the big Attack comes, simply pile an immense heap of rusting iron in one corner. It slowly sheds oxygen, therefore allowing you to live off of it for a long period of time.

Neil Young was right. Rust really never sleeps !! :smiley:

<further nitpick>

Do you mean iron(II) hydroxide or iron(III) hydroxide?

Or in older terminology, ferrous hydroxide or ferric hydroxide?

Derleth was on the right track. “Iron hydroxide” is not specific enough (and therefore is improper terminology), because iron has multiple oxidation states.

<further nitpick/>

Rusting iron uses up oxygen. It does not give off oxygen. Both the iron (which oxidizes) and the oxygen (which is reduced) are more stable when chemically combined in the form of rust than they are in their elemental form.

Oh. My apologies. I misunderstood.

Yes, all very good; go to the top of the chemistry class, but go back to the reading comprehension class.
Derleth said iron oxide aka rust, and Mangetout pointed out that the anion was hydroxide, not oxide.

If one wanted to be really nitpicky, one could say that iron hydroxide is aka rust, but rust is only ever ferric hydroxide.
Iron oxide, which only exists with Fe in a III or ferric state, is never rust.