6. Compute OH (av). (a) for the gas X as an ideal gas (b) for gas X as a real gas and obeys van der Waals equation as follow p + and Vz ( V - nb ) = nRT 7. One mol of gas X obeys the following equation of state and has a constant a = 1.639 L2 atm mol-2 K and b = 0.03049 L mol-1. The gas was expand isothermally from 20 L to 50 L at 300 K. (P + TMZ TVz) (V - b) = RT (a) Compute AU and AS for the process. (b) Compute AU and AS for the process if the gas considered ideal. (c) Comment your result in part (a) and (b). 8. Show that for an ideal gas, ov nRT (a) as) PCp d'T (b) ap) = 0 9. (a) Show that for ideal gas, (ov ), = CVP R (b) Calculate AU from the relation in part (a)