A 30-m3 tank contains 14 m3 of liquid n-butane in equilibrium with its vapour at 25C. Estimate the mass of n-butane in the tank. The vapour pressure of n-butane at the given temperature is 2.43 bar. Use Pitzers and Racketts equations when applicable.

1) Calculate the mass of n-butane vapour

2) Calculate the mass of n-butane liquid

3) The total mass of n-butane in the tank