Explain why, at very high temperatures and low pressures, the behaviour of a real gas approaches that of an ideal gas.

At very high temperatures the average kinetic energy of the gas molecules is large, so the kinetic energy of the molecules far exceeds the energy of any intermolecular attractions. Consequently the attractive forces become negligible and the molecules behave as if they do not attract each other. At very low pressures the molecules are far apart, so the volume occupied by the molecules themselves is very small compared with the total volume of the container. Thus the assumption of negligible molecular volume is satisfied. Because both key assumptions of the ideal gas model – negligible molecular volume and negligible intermolecular forces – are met, the real gas follows the ideal gas law pV=nRT.