It wouldn't so much catch on fire as revert to gas, straight from solid to H2. O...

ars · on Dec 11, 2014

Oh, there will be fire. The amount of energy going from H to H2 is more than there is from H2 to H2O.

If this really is atomic hydrogen it holds a ferocious amount of energy.

andrewflnr · on Dec 11, 2014

Yes, my point was that it doesn't make any sense to call that a fire. H(s) to H2(g) is a highly exothermic phase change. Fire is oxidation.

ars · on Dec 12, 2014

That's not a phase change (despite the solid to gas), that's a chemical reaction.

Fire is oxidation yes, but despite the name oxidation does not require oxygen, it just requires electron transfer, which happens here.