Three gases, nitrogen , argon , and krypton are confined in a 9.00 L vessel at a
ID: 795102 • Letter: T
Question
Three gases, nitrogen, argon, and krypton are confined in a 9.00 L vessel at a pressure of 11.0 atm. The vessel contains 2.00 moles of nitrogen, 3.00 moles of argon, and 4.00 moles of krypton. What is the partial pressure of krypton?
Partial pressure of krypton = atm
Now suppose that 3.00 moles of xenon are added to the vessel without changing the volume or temperature. What is the partial pressure of krypton now?
Partial pressure of krypton after addition of xenon = atm
Now suppose that an additional 4.00 moles of krypton are added to the vessel, again without any change in the volume or the temperature. What is the partial pressure of krypton now?
Partial pressure of krypton after addition of 4.00 more moles of krypton = atm
Explanation / Answer
mole fraction Ar = moles Ar / total gas moles = (5.00) / (11.00) = 0.455
P Ar = (mole fraction Ar)(P total) = (0.455)(4.00 atm) = 1.82 atm
======================================...
new mole fraction Ar = moles Ar / total gas moles = 5.00 / 13.00 = 0.385
When you add 2.00 moles of O2 gas into a fixed-volume container at a fixed temperature, the pressure will increase proportional to the moles of gas added, but the P Ar will remain the same. Don't believe it???
P1/n1 = P2/n2
4.00 atm / 11.00 gas moles = P2 / 13.00 gas moles
P2 = 4.73 atm
new P Ar = (new mole fraction Ar)(new P total) = (0.385)(4.73 atm) = 1.82 atm . . .no change!
======================================...
new mole fraction Ar = 8.00 moles Ar / 16.00 total gas moles = 0.500
P1/n1 = P2/n2
4.73 atm / 13.00 moles = P2 / 16.00 moles
P2 = 5.82 atm
new P Ar = (new mole fraction Ar)(P total) = (0.500)(5.82 atm) = 2.91 atm