Determining the molecular mass by the ideal gas law

All gases comply with the ideal gas law which connects pressure p, volume V, temperature T and the moles of substance n. If the volume occupied by a known mass of gas is measured at certain values of temperature and of pressure, the ideal gas law enables to determine the molecular mass of the gas. The test that can be carried out with this equipment enables to determine the molecular masses of some gases such as helium, nitrogen, carbon dioxide and methane.