1. A rigid, insulated vessel contains superheated vapor steam at 400 lbf /in.2, 700 F. A valve on the vessel is opened, allowing steam to escape. It may be assumed that the steam remaining inside the vessel goes through a reversible adiabatic expansion. Determine the fraction of steam that has escaped when the final state inside is saturated vapor.
2. Two 5-lbm blocks of steel, one at 500 F and the other at 80 F, come in thermal contact. Find the final temperature and the change in the entropy of the steel.