5 dm3 of carbon monoxide, CO(g), and 2 dm3 of oxygen, O2(g), at the same temperature and pressure are mixed together. Assuming complete reaction according to the equation given, what is the maximum volume of carbon dioxide, CO2(g), in dm3, that can be formed?
2CO(g) + O2(g) → 2CO2(g)
The answer is 4, but I don't know how to get there, can someone please explain this. Am I supposed to change the dm3 to moles?