Blast furnaces extra pure iron from the Iron(III) oxide in Iron ore in a two step sequence. In the first step, carbon and oxygen react to form carbon monoxide:
2C(s) + O2(9) arrow 2 CO(g)
In the second step, Iron(III) oxide and carbon monoxide react to form Iron and carbon dioxide:
Fe2O3(s) + 3 CO(g) → 2 Fe(s) + 3CO2(g)
Suppose the yield of the first step is 97.% and the yield of the second step is 89.%. Calculate the mass of oxygen required to make 5.0 kg of iron.
Be sure your answer has a unit symbol, if needed, and is rounded to 2 significant digits.