How many grams of CO are required to completely react with 100. g Fe2O3?

Fe₂O₃ + 3CO → 2Fe + 3CO₂

moles of Fe₂O₃ = mass : molar mass

= 100 g : [ (56 * 2) + (16 * 2) ] g/mol

= 100 g : 144 g/mol

= 0.694 mol

mole ratio of Fe₂O₃ : CO is 1 : 3

∴ if mole of Fe₂O₃ = 0.694 mol

then mole of CO = 0.694 * 3

= 2.083 mol

mass of CO = mole * molar mass

= 2.083 * (12 + 16) g/mol

≈ 58.33 g