Problem 2.14. Compute the Helmholtz free energy for a van der Waals gas. The equation of state is (P+ (an/V2)) (V - nb) = nRT, where a and b are constants which depend on the type of gas and n is the number of moles. Assume that the heat capacity is Cvn (3/2)nR. Is this a reasonable choice for the heat capacity? Should it depend on volume?