Consider two identical rigid containers filled with the same mixture of oxygen a
ID: 715583 • Letter: C
Question
Consider two identical rigid containers filled with the same mixture of oxygen and helium at constant temperature. The total pressure of the gases in each container is initially the same. By decreasing the volume of container (1), the pressure of the He and O2 mixture was doubled. The pressure in container (2) was also doubled by pumping some argon into it. Did the partial pressure of He, pHe, change in these two containers?
a.)pHe increased by a factor of 2 in both containers.
b.)pHe increased in both containers by a factor equal to the fraction of He in the gas mixture.
c.)pHe increased by a factor of 2 in container (2) but did not increase in container (1).
d.)pHe remained unchanged in both containers.
e.)pHe increased by a factor of 2 in container (1) but did not increase in container (2).
Explanation / Answer
Answer is e)
The partail pressure of Helium will increase in container (1), with decrease in volume of the container beacause as per ideal gas equation; PV= nRT (P= nRT/V) )the pressure of gas does depends upon the volume of the container.
Whereas in container (2), on pumping Argon gas in the container the Total pressure of the gas does increased but the partial pressure of helium remained the same. This is because as per the above equation P= nRT/V, any of the factors have not been changed.
And according to Dalton's Law of Partial Pressure, the total pressure exerted by a mixture of gases is the sum of the partial pressures of component gases. So the increase in the total pressure is due to the addition of partial pressure of argon.