Answer:
13.5 moles of H₂O
Explanation:
We determine the reaction
2Fe + 3H₂O → Fe₂O₃ + 3H₂
2 moles of iron react with 3 moles of water, in order to produce 3 moles of hydrogen and 1 mol of iron (III) oxide.
Ratio is 2:3, so let's make a rule of three:
2 moles of iron need 3 moles of water to react
Then, 9 moles of iron will react with (9 . 3) /2 = 13.5 moles of H₂O
