A spherical elastic balloon initially containing 5 kg ammonia as saturated vapor at 20C is connected by a valve to a 3-m3 evacuated tank. The balloon is made such that the pressure inside is proportional to the diameter. The valve is now opened, allowing ammonia to flow into the tank until the pressure in the balloon has dropped to 600 kPa, at which point the valve is closed. The final temperature in both the balloon and the tank is 20C. Determine
a. The final pressure in the tank
b. The work done by the ammonia