Three bulbs are connected as shown in the diagram below. For purposes of a biology experiment, an artificial atmosphere is being created for test animals to breathe. What is the partial pressure of oxygen inside the system when all the valves are opened and the gases mix completely? The flasks are at the same temperature, and the temperature does not change when the gases mix. Assume the volume of the tube connecting the bulbs is negligible.

Question

Quizplus · Accepted Answer

According to Dalton's law of partial pressures, the total pressure in the system is equal to the sum of the partial pressures of each gas. 
Since the initial pressure of oxygen in bulb B is 0.2 atm, and the total pressure in the system is 1.0 atm (given), the pressure contributed by gases in bulbs A and C must be 1.0 - 0.2 = 0.8 atm. 
Since the ratio of the volume of bulbs A:C is 1:2, the pressure contributed by gas in bulb C must be twice that of bulb A. 
Let x be the pressure contributed by gas in bulb A. 
Thus, the equation becomes: 
x + 2x + 0.2 = 0.8 
3x = 0.6 
x = 0.2 
Therefore, the partial pressure of oxygen (gas in bulb A) in the system is 0.2 atm.

Three Bulbs Are Connected as Shown in the Diagram Below