Question

Container A holds 762 mL762 mL of an ideal gas at 2.80 atm.2.80 atm. Container B holds 149 mL149 mL of a different ideal gas at 4.60 atm.

If the gases are allowed to mix together, what is the resulting pressure?

Answer 1

METHOD 1

From Dalton's law of partial pressures, we know that, in a mixture of gases, the total pressure is the sum of their individual partial pressures.

where, and are the partial pressures of the gases in the gas mixture.

So, we have to calculate the partial pressures of the gas A and gas B individually in the mixture using Boyle's law, assuming them to behave ideally, and adding them will result in the final pressure of the gas mixture. This is one method.

METHOD 2

Alternatively, we can also use Boyle's law (P.V=constant) to set up an equation like below.

Here we are treating the gases as an ideal gas and we can calculate the from the above equation. The thing should be remembered that in the above equation, PA and PB are not the partial pressures as the first method. Pa and Pb are the individual pressures of the gases as provided to us.

Let us jump into the calculations now-

Hence, the resulting pressure of the gas mixture is - .