A 10 ft3 vessel contains steam at 200 psi and 500°F. A valve on top of the vessel is opened and steam is expelled to the surroundings until the pressure reaches 60 psi, at which time the valve is closed and the temperature inside is measured to be 350°F. Determine the net change in entropy for this process. Assume the surroundings to be at 500°F. Show all work.