Carbon monoxide (CO) gas reacts with oxygen (O2) gas to produce carbon dioxide (CO2) gas. If 1.00 L of carbon monoxide reacts with excess oxygen at standard temperature and pressure, what volume of carbon dioxide is produced? What mass of carbon dioxide is produced?

The balanced reaction would be:

2CO + O2 = 2CO2

We assume that the gases are ideal gas so that we use the relation that 1 mol of an ideal gas is equal to 22.4 L of the gas at STP. From that relation, we get the number of moles and we can convert it to other units. We do as follows:

1.0 L CO (1 mol / 22.4 L) (2 mol CO2 / 2mol CO) = 0.045 mol CO2 produced

0.045 mol CO2 (22.4 L / 1 mol) = 1 L of CO2

0.045 mol CO2 (44.01 g / 1 mol) = 1.98 g of CO2