1. The problem statement, all variables and given/known data Given 2 tanks A and B. Tank A has a volume of 2m3 and contains air at pressure 1 bar absolute Tank B has a volume of 1m3 and contains air. Tank A and B and interconnect with a pipe and has a stopcock and is currently closed. What is the pressure or air that would be needed in Tank B such that after the stopcock is opened and pressures in both tanks have equalized the pressure in both tanks now is 0.8 bar. 2. Relevant equations Can the equation Code (Text): P1V1 = P2V2 be used for solving this problem. I'm a bit wary about this since boyles law applies to a since this problem involves 2 cyclinders can we consider the gas to be 3. The attempt at a solution P1 = ? V1 = 1m3 P2 = 0.8bar V2 = 2 + 1 = 3m3 P1 = (0.8 * 3) / 1 P1 = 2.4bar Which seems to be incorrect, intuitively I would have said that the pressure in the smaller tank (tank B) should have been below 1 bar to get the equalization pressure to 0.8 bar. Where am I going wrong?