Consider the following reaction.

4 Al(s) + 3 O2(g) → 2 Al2O3(s)
It takes 1.00 L pure oxygen gas at STP to react completely with a certain sample of aluminum. What is the mass of aluminum reacted?

1 answer

Just follow the steps in this worked example of a stoichiometry problem.
http://www.jiskha.com/science/chemistry/stoichiometry.html