1. The problem statement, all variables and given/known data There is some gas in a baloon. The volume of the baloon is V and the gas is under a pressure of 2P0 ---where P0 is atmospheric pressure. The gas is allowed to come very slowly out of the ballon and eventually the gas pressure decrease to P0. How much work is done? Where does the energy required to do work come from? Thx 2. Relevant equations PV=nRT 3. The attempt at a solution My solution: gas comes out slowly so we can assume the process to be isothermal. So boyles law it applicable. So when gas pressure is halved the volume is doubled (2V). so work= integration of PdV = integration of K/V*dV (k=2PoV=boyle's constant) = K*In2 =2PoV*In2 But the answer is PoV. Can you explain why?