Question

Imagine that you have a 6.50 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 155 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. express your answer with the appropriate units.

Answer 1

V₁(O2) = 6.50  L                
p₁(O2) = 155 atm          
V₂(acetylene) = 4.50 L                   
p₂(acetylene) =?                             

According to Boyle–Mariotte law (At constant temperature and unchanged amount of gas, the product of pressure and volume is constant) we can compare two gases that have ideal behavior and the law can be usefully expressed as:

V₁/p₁ = V₂/p₂

6.5/155 = 4.5/p₂

0.042 x p₂ = 4.5

p₂ = 107.3 atm