1. The problem statement, all variables and given/known data Consider a pump that is required to compress air in a factory. The cylinder in the pump has an inner diameter of 2.00 cm and length 60.0 cm. Air is drawn into the pump at atmospheric pressure and 18°C and the pump adiabatically compresses the air to a pressure of 17 atmospheres. Calculate the volume and temperature of the compressed air. I calculated the volume to be 24.9153 cm3, and the temperature to be 653.8 Kelvin. Volume was found by using the P1V1gamma = P2V2gamma formula, presuming it was a diatomic gas (air), and for temperature just used P1V1/T1 = P2V2/T2 (or could have used the T1V1^gamma-1) But this question stumps me: What is the increase in internal energy of the gas during the compression? 2. Relevant equations Eint = (5/2) * n * R * T Eint = (5/2) * N * Kb * T ΔE = Q + W W = PΔV 3. The attempt at a solution My first thought was to use the top equation with the different temperatures and minus them from each other, but realised I didn't have the amount of moles. My second thought was to use the last equation and sub it into the second to last equation (I know Q=0 since it's adiabatic), but was confused about what pressure to use? Would I use 101300 Pa, or 1722100 Pa (which is 17 atm), or neither?