Question

if you imagine that you have a 6.00 L gas tank and a 4.50 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 115 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.

Answer 1

As you mentioned in question, I am assuming, this is supposed to be an ideal gas equation.

The balanced equation is -

C2H2 + 5/2O2 = 2CO2 + H2O

Therefore, you need 2.5 times as much oxygen as acetylene to fully react both the two gases.

Looking at the ideal gas equation PV=nRT has n = PV/RT

Assuming the temperature is constant for the two gases, the product of the pressure and volume is directly related to the number of moles.

The amount of oxygen you have is 6 L X 115 atm = 690 Latm

For the acetylene as said above, you need only 1 / 2.5 times as much or 690 L atm / 2.5 = 276 L atm.

The volume of the smaller tank is 4.5 L so the pressure you need = 276L atm / 4.5 L = 61.34 atm

So answer is 61.34 atm