Energy change of apparatus when gas suddenly expands 1. The problem statement, all variables and given/known data A gas is confined in a cylinder by a piston. The initial pressure of the gas is 7 bar(700kPa), and the volume is 0.10m^3. The piston is held in place by latches in the cylinder wall.The whole apparatus is placed in a total vacuum. What is the energy change of the apparatus if the restraining latches are removed so that the gas suddenly expands to double its initial volume, the piston striking other latches at the end of the process? Data known: P(initial) = 700kPa V(initial) = 0.10m^3 V(final) = 0.2m^3 2. Relevant equations Energy change = W = PΔV 3. The attempt at a solution Since the gas suddenly expands (not a quasi-equilibrium process), the PV ln (V2/V1) equation cannot used. But still, my lecturer gave me zero. I want to know the right way to solve this problem. God bless you all.