Helium in a steel tank is at 40 psia, 540 R with a volume of 4 ft3. It is used to fill a balloon. When the tank pressure drops to 24 psia the flow of helium stops by itself, if all the helium still is at 540 R how big a balloon did I get? Assume the pressure in the balloon varies linearly with volume from 14.7 psia (V = 0) to the final 24 psia. How much heat transfer did take place?