In this experiment, the aim is to calculate the molecular mass of butane gas using a measuring cylinder and the ideal gas equation. By filling an inverted measuring cylinder with a known mass and volume of butane gas and using either the ideal gas equation or the assumption that a mole of gas will occupy 24dm3 at rtp or 22.7dm3 at stp, the molecular mass of butane can be determined. Safety precautions must be taken while handling butane gas. The experiment provides an opportunity to calculate the number of moles of gas introduced, the molecular mass of the gas, and the density of butane at r.t.p. Calculations can be made to determine the percentage difference between the molecular mass calculated using the ideal gas equation and the molar gas volume equation.