An iron ore sample is impure Fe2O3. When Fe2O3 is heated with excess carbon, iron metal is produced. A 7.720 g sample of ore yields 4.53 g of Fe. What is the percent, by mass, of Fe2O3 in the ore? (Atomic mass: Fe 55.85, O 16.00).
Moles Fe 4.53 / 55.85 0.0779 Moles Fe2O3 0.0779 /2 0.0389 Molar mass Fe2O3 159.7 g/mol Mass Fe2O3 159.7 g/mol x 0.0389 mol 6.212 g 6.212 x 100 / 7.720 80.5 %
