1. The problem statement, all variables and given/known data A thermally isolated chamber is pumped down to a very low pressure. At some point, the chamber is vented slowly so that it is filled with air up to atmospheric pressure, whereupon the valve is closed. The temperature of the air surrounding the chamber is T0=300 K. What is the temperature T of the gas in the chamber immediately after the valve is closed. γ=Cp/CV=7/5 for air. (ANS: 420K) 2. Relevant equations Has the air done any work? Does low pressure means vacuum? 3. The attempt at a solution T0/V0=T/V But what is V0?