I know this question is easy, but for some reason I am unable to figure it out. The first part of the problem wants to know what the volume is in a pressurized tank. I figured it and it equals 2.1 ft^3. The second part asks for the specific volume at 70 F and 200 psi. So far all I have is v(specific volume) = V/m. Or 1/d = v The gas in the tank is air, so basically I need to find the mass of air @ 70 F and 200 psi. I have the volume, so that is not the problem. The answer to the question is .98 ft^3/lbm Should I be using ideal gas laws? If I do use the ideal, I'm assuming I need to convert units. I'm having a problem converting psi to lbf/ft^2... I can't come up with this answer, so if anyone can give me a hand I would appreciate it. Thanks, Frustr8ed, as the name states.