Question

If 2.0 liters of oxygen gas react with excess carbon monoxide at STP, how many liters of carbon dioxide can be produced under the same conditions?

2 CO (g) + O2 (g) 2 CO2 (g)

Answer 1

For gasses, every mole occupies 22.4 liter
So when 2 liter oxygen reacts with carbon monoxide, twice the amount carbon dioxide is produced, because there's a 2 before CO2 and nothing before O2 (you could say 1 O2)

So twice the amount is produced, thats 4.0 liter CO2