1. The problem statement, all variables and given/known data A bottle at 323 K contains an ideal gas at a pressure of 1.667×10^5 Pa. The rubber stopper closing the bottle is removed. The gas expands adiabatically against P(ext)=1.162×10^5 Pa, and some gas is expelled from the bottle in the process. When P=P(ext), the stopper is quickly replaced. The gas remaining in the bottle slowly warms up to 323 K. I have to find the final pressure for a monatomic gas...that is, Cv,m=3R/2. 2. Relevant equations T(final) = T(initial) ((Cv,m + (RP(ext)/P(initial)))/(Cv,m + (RP(ext)/P(final))) 3. The attempt at a solution I know that P(initial) = P(external) (making this a reversible process), but I don't know how to find T (initial) (after the stopper is removed)... Thank you!