A 22. 4 l high pressure reaction vessel is charged with 0. 5020 mol of iron powder and 1. 39 atm of oxygen gas at standard temperature. On heating, the iron and oxygen react according to the balanced reaction below. 4fe(s) + 3o2(g) → 2fe2o3(s) after the reaction vessel is cooled, and assuming the reaction goes to completion, what pressure of oxygen remains?.