Depleted air from an industrial exhaust system contains 16% oxygen by volume. Calculate the volume of this depleted air, in dm3\text{dm}^3dm3, needed to provide enough oxygen to react completely with 3.20 dm3 of methane gas.
The balanced chemical equation for the combustion is:
CH4(g)+2O2(g)→CO2(g)+2H2O(g) \text{CH}_4\text{(g)} + 2\text{O}_2\text{(g)} \rightarrow \text{CO}_2\text{(g)} + 2\text{H}_2\text{O(g)} CH4(g)+2O2(g)→CO2(g)+2H2O(g)