Water initially at 200 kPa and 300C is contained in a pistoncylinder device fitted with stops. The water is allowed to cool at constant pressure until it exists as a saturated vapor and the piston rests on the stops. Then the water continues to cool until the pressure is 100 kPa.

a) Find the overall change in internal energy between the initial and final states per unit mass of water.

b) sketch the Pv, T-v, and T-P diagrams.

1