Imagine that you have a 6.00L gas tank and a 3.00L 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 125atm , 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.

Question

Note: Acetylene torches are used for welding. These torches use a mixture of acetylene gas, C2H2, and oxygen gas, O2 to produce the following combustion reaction:
2C2H2(g)+5O2(g)→4CO2(g)+2H2O(g)

Answer 1

You have 5 O2 molecules for every 2 acetylene molecules
P V = n R T
where n (mols)is proportional to the number of molecules
so for O2
125 (6) = 5 k R T for O2
P(3) = 2 k R T for C2H2

k R T are the same for both
so
125(6/5) = P(3/2)

Answer 2

5142