Question

Imagine that you have a 5.50 l gas tank and a 4.00 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 145 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

To solve this problem, we must first assume that the two gases acetylene and oxygen to act like an ideal gas so that we can use the ideal gas equation:

P V = n R T

where,

P is the pressure inside the tank, V is the volume of the tank, n is the number of moles of gas, R is the universal gas constant and T is the absolute temperature

 

Now to ensure that we run out of each gas at the same time, we must also assume that n and T are equal for both gases, therefore:

P V = constant

 

So now we can equate the PV for the two gases to find for the pressure of the other tank:

145 atm (5.50 L) = P (4.00 L)

P = 199.375 atm