posted by Student
Two gases are mixed in a 10.0L fixed volume flask: 8.0 L of O2 at 2.00 atm and 2.0 L of N2 at 3.00 atm.
A) Calculate the partial pressure for each gas and the total pressure.
I got ...
PO2 = 1.60 atm
PN2= 0.600 atm
B) How much (volume in liters) argon at 5.0 atm must be added to the 10.0 L flask to lower the mole fraction of oxygen to 1/2 ( i.e., to get XO2=0.5)?
Hint: maybe it is easier to do part C first?
C) What is the total pressure from part B (Ar, O2, N2)?
A is ok but you didn't calculate the total pressure. Of course, it's 2.2 atm.
B. You want XO2 to be 0.5
(pO2/Ptotal) = 0.5
What must total pressure be.
(1.6/y) = 0.5
Solve for y and you get 3.2 for the total pressure; i.e., that way, 1.6/3.2 = 0.5
So what pAr is needed.
Ptotal = pO2 + pN2 + pAr
Solve for pAr.
Then pAr x (z/10) = 5 x (z/10) = volume Ar in L.