The mass of iron converted into Fe₃O₄ by the action of 18 g of steam is : (Given : Molar mass of H, O and Fe are 1 , 16 and 56 g mol ⁻¹ respectively) Assume iron is present in excess :

Step-by-step solution

The balanced chemical equation for the reaction of iron with steam is: 3Fe + 4H₂O Fe₃O₄ + 4H₂ Molar mass of H₂O = 2 1 + 16 = 18 g mol ⁻¹ Number of moles of steam ( H₂O ) given = 18 18 = 1 mol From the balanced equation, 4 moles of H₂O react with 3 moles of Fe . Therefore, 1 mole of H₂O will react with 3 4 moles of Fe . Mass of iron reacted = Moles of Fe Molar mass of Fe Mass of iron = 3 4 56 = 3 14 = 42 g Answer: 42 g