Question

Q3) Consider a 10 L container at 0 oC with 40 grams of He and 40 grams of Ar gases:

a) Calculate the partial pressure of Ar in the container?
b) Calculate the partial pressure of He in the container?
c) What is the total pressure of the container?

Answer 1

Convert 40 g He to moles. moles = grams/molar mass.
Convert 40 g Ar to moles.
Add moles = total n and substitute into PV = nRT and solve for total pressure. That's c.

a and b parts.
Calculate mole fraction He and Ar.
XHe = n He/total moles.
XAr = n Ar/total moles.

PAr = XAr x Ptotal
PHe = XHe x Ptotal.

This can be done another way which may be easier.
moles He = grams/molar mass
moles Ar = grams/molar mass.
Use PV = nRT and substitute n He and solve for PHe.
Use PV = nRT and substitute n Ar and solve for PAr.
Then total P = PHe + P Ar.