chemistry
posted by unknown on .
Imagine that you have a 5.50 L gas tank and a 3.50 L gas tank. You need to fill one tank with oxygen and the other with acetylene to use in conjunction with your welding torch. If you fill the larger tank with oxygen to a pressure of 105 atm , to what pressure should you fill the acetylene tank to ensure that you run out of each gas at the same time? Assume ideal behavior for all gases.

Use PV = nRT for the 5.50 L tank of oxygen. Calculate n = # mols O2 in the tank. There is no T listed so pick any T and use it throughout the problem. I would pick 27 C because that's 300 K and that is very close to room T. (Don't forget to use Kelvin for T in PV = nRT).
Using n mols oxygen, and the equation you wrote earlier, calculate mols acetylene needed to exactly react with the oxygen in the 5.50 L tank. Then use PV = nRT again and solve for P of the acetylene in the 3.5 L tank. 
84.86

60.0 atm