1. The problem statement, all variables and given/known data A leaky cylinder, at 0oC contains gas with a pressure of 18.0 atmospheres. After being kept at 20oC for 24 hours, the pressure is now 16.3 atmospheres and the masss has fallen by 1.2kg. What was the gas' original mass? 2. Relevant equations 3. The attempt at a solution My only thought on how to tackle this is far to simple and ignores important factors like the temperature. All I could think of doing was diving 1.2 by 1.7 to get the mass per atmosphere and then multiply that by 18, however I know this will not be right. Any help appreciated.