Find the number of moles of water that can be formed if you have 210 mol of hydrogen gas and 100 mol of oxygen gas.

The answer is 200 mol of water. The balanced reaction is 2(H2) + (O2) = 2(H2O) The limiting reactant is O2 as it will be completely consumed first, before hydrogen gas. Hydrogen gas would need at least 105 mol oxygen gas to be consumed; in excess of the 100 mol O2. Looking at the stoichiometric coefficients, the ratio between water and oxygen is 2:1. Therefore, the water produced would be 200 moles.