Lecture 6 -- Pressure of an ideal gas
Having considered the average energy of an ideal gas, we now turn to the calculation of another simple mechanical property, namely the pressure P: the force per unit area that a gas exerts on the walls of its container. This Lecture presents three physically distinct calculations of the P, all of which give the ideal gas law
in the appropriate limits. The first calculation uses a direct approach based on Gibbs' ensemble method. In a second calculation, P is obtained by a thermodynamic derivative from a free energy. Finally, P will be found using a kinetic argument, based on counting collisions of gas molecules with container walls over a period of time.