Assuming all volume measurements are made at the same temperature and pressure, what volume of hydrogen gas is needed to react completely with 4.55 L of oxygen gas to produce water vapor?

9.1L

Explanation:

Firstly, to solve the problem, we need a balanced chemical equation.

2H2 + O2 - --> 2H2O

2 moles of hydrogen reacted one mole of oxygen. Now, we know that at STP, one mole of a gas occupies a volume of 22.4L, now let us get the number of moles in 4.55L of oxygen.

This means 4.55/22.4 = 0.203125 mole

Since in theory we have 2 moles of hydrogen reacting one mole of oxygen. Hence the number of moles of hydrogen we have is 0.203125 * 2 = 0.40625 mole

We now proceed to get the volume of hydrogen gas. Since 1 mole is 22.4L, then

0.40625 Is 0.40625 * 22.4 = 9.1L