Question

You are asked to make 112 g of iron from iron oxide and excess carbon monoxide.

Fe2O3(s) + 3CO(g)→2Fe(l) + 3CO2(g)

Approximately how many grams of iron oxide is used?

Responses

107 g
107 g

160 g
160 g

240 g
240 g

720 g

720 g

Answer 1

Molar masses: Fe ≈ 55.85 g·mol⁻¹, Fe2O3 ≈ 2(55.85)+3(16.00)=159.7 g·mol⁻¹.

Moles Fe needed = 112 g / 55.85 g·mol⁻¹ = 2.00 mol Fe.
From the equation 1 mol Fe2O3 → 2 mol Fe, moles Fe2O3 = 2.00 / 2 = 1.00 mol.
Mass Fe2O3 = 1.00 mol × 159.7 g·mol⁻¹ ≈ 160 g.

Answer: 160 g.