The combustion of propane (C 3H 8) in the presence of excess oxygen yields CO 2 and H 2O: C 3H 8 (g) + 5O 2 (g) → 3CO 2 (g) + 4H 2O (g) When 2.5 mol of O 2 are consumed in their reaction, ________ mol of CO 2 are produced.