Connected Container Problems

Connected container problems use a piece of equipment that serves NO purpose except to create this type of Dalton's Law Problem.

Here is a sample problem and a diagram to go along with it.

If the valve in the picture below is opened, what will the final pressure in the container be?

The key to solving this problem is to remember that gases act independently.

In simple terms, the hydrogen on the left will act as if the right side of the container is empty and will expand to fill all of the available space.  (The final volume is just the sum of the volumes on the left and right.)

	initial	final
pressure	2.00 atm	?
volume	1.00 L	5.00 L

Determining what happens to the pressure of the hydrogen is then a simple IF problem.

At the same time, the argon on the right side will expand into the left, as if it were empty – another IF problem.

	initial	final
pressure	3.00 atm	?
volume	4.00 L	5.00 L

Determining what happens to the pressure of the nitrogen is another simple IF problem.

The total pressure is simply the sum of the pressure of the hydrogen and the pressure of the nitrogen: