chemistry
posted by unknown on .
Imagine that you have a 5.00L gas tank and a 3.50L 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 145atm , 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.

2C2H2 + 5O2 ==> 4CO2 + 2H2O
For the large tank, n = PV/RT
Solve for n = # moles O2
Convert mols O2 to moles C2H2 and use PV = nRT and solve for P. I get a little over 500 atm.