1. The problem statement, all variables and given/known data Gaseous helium is contained in a rigid container with a volume of V=0.5 m3, and is initially at a pressure of 500 kPa. Agitation by a stirrer transfers 250 kJ of work to the gas in an adiabatic process. Cv for the gas is constant and equal to 12.46 kJ/kmol*K. What is the final pressure of the gas? So At state 1: V=0.5 m3, P=500 kPa, Process 1->2: W=-250kJ At state 2: V=0.5 m3, P=? cv=12.46kJ/kmol*K 2. Relevant equations Energy balance for the process: Q-W=deltaU+deltaKE+deltaPE Q=deltaPE=deltaKE=0 so -W=deltaU, W=-250kJ so 250kJ=deltaU. 3. The attempt at a solution This is what I have: 250kJ=deltaU=n*deltau where u=U/n and n is the number of moles of helium. cv=du/dT so deltau=cv*deltaT and 250 kJ=n*cv*deltaT I don't really know where to go with this problem to find anything to do with the pressure, the equation seems underdetermined. Help?