CHEM AL 急

At 233 K, the container contains only N2 with a pressure 1.5 atm.

Find the pressure of N2 at 473 K:
When T1 = 233 K, P1 = 1.5 atm
When T2 = 473 K, P2­ = ?

Apply pressure law: P1/T1 = P2/T2
P2 = P1x(T2/T1)
P2 = 1.5 x (473/233) atm
P2 = 3.045 atm

Partial pressure of N2 at 473 K = 3.045 atm

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At 473 K, the container contains N2 and C3H8.

Total pressure, PT = pN2 + pC3H8 = 4.5 atm

But pN2 = 3.045 atm

Then pC3H8 = (4.5 - 3.045) atm
Then pC3H8 = 1.455 atm

Apply Dalton’s law of partial pressure: pC3H8 = XC3H8∙PT

Mole fraction of C3H8 = pC3H8/PT
Mole fraction of C3H8 = 1.455/4.5
Mole fraction of C3H8 = 0.3233
=

2008-09-01 17:11:11 補充：
The volume of the system is equal to the capacity of the container. The volume is thus approximately constant because the change of the volume of the container due to temperature change is negligible.