1. The problem statement, all variables and given/known data So, this question is to do with an experiment which investigates the operations of a pneumatic pump. You're asked to find the mass of air displaced in each 30 second period using the atmospheric pressure, temperature and theoretical displacement of the compressor. Also, you are told to use 2 of following equations: PV = mRT and P1V1n = P2V2n. 2. Relevant equations Given in question. 3. The attempt at a solution Well, the theoretical displacement is given as 106 l/min. Thus for a 30 second cycle, V = 53 l. Does it not make sense just to use PV = mRT for this? How is P1V1n = P2V2n relevant? Thanks.