Two pounds of ammonia in a cylinder restrained by a piston is initially at pressure 100 psia and quality 0.9. two processes act on the ammonia one after the other. neglect kinetic and potential energy effects. the two processes are: process 1-2: constant pressure cooling to quality 0.75. process 2-3: heating at constant volume until the ammonia is saturated vapor. determine work and heat transfer for process 1-2, in btu.