Water initially at $200$ kPa and $300C$ is contained in a piston$-$cylinder 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 untif the pressure is $100$ kPa $.$ On the T$-$y diagram, skeich,

with respect to the saturation lines, the process curves passing through the

initial, intermediate, and final states of the water. Label the $I_{,}{P}_{?},$ and $v_{?}$ values

for end states on the process curves. Find the overall change in internal

energy between the initial and final states per unit mass of water.