Hydrogen Room

[datatec]

What would happen if I lit a match in an air-tight room completely filled with hydrogen?

[Rogerio]

Nothing...

[chroot]

With no oxidizer present, very little would happen.

- Warren

[ExtravagantDreams]

would the match even light if there was no oxygen in the room?

[marcus]

would the match even light if there was no oxygen in the room?

yes
when I was 8 years old the 7 year old next door to us down the street
performed an experiment with wooden strike-anywhere "kitchen matches"
that demonstrated this, which was not a good thing

all the matches I know of have the oxidizer mixed in
like in gunpowder there is KNO3 which will not burn but
which will supply oxygen to charcoal powder so that the charcoal will burn
that is roughlyspeaking why you mix KNO3 with charcoal (and sulphur)
to make black gunpowder

you dont have to have air in order to have an oxidation reaction
matches would strike in a vacuum, and flare briefly but quickly go out

[Gokul43201]

The explosive region of the hydrogen-oxygen mixture diagram is between about 10% and 90% oxygen - if I recall correctly. With less or more oxygen than that you don't get an explosion.

You could get some oxygen from outgassing from the match (matchbook) or your breathing apparatus, but it probably won't be enough to ignite the hydrogen.

I'm not sure if other reactions are possible, though. For instance, under the right conditions, hydrogen will reduce carbon dioxide to carbon monoxide (or even plain carbon ?) and water vapor. I'm not sure of the energetics for that reaction.