What is the degree of dissociation?

[zorro]

Homework Statement

At 627 C and 1 atm pressure, SO3 partially dissociated into SO2 and O2 by SO3--->SO2 +1/2O2. The density of equilibrium mixture is 0.925g/L. What is the degree of dissociation?

Homework Equations

The Attempt at a Solution

I found out the average molecular weight of the mixture by the formula PM=DRT
where D is the density.

Then, average molecular weight = sum of product of mole fractions and molar mass
moles at equilibrium-
SO3- 1-x
SO2- x
O2- x/2

But I did not get correct answer.
The answer is 0.34
Please provide a detailed explanation

 

[Borek]

Show more details of your work.

 

[zorro]

M= DRT/P
M=0.925 x 0.0821 x 900/1= 68.3

this average molecular weight = [80(1-x) + 64x + 32(x/2)] / (1+x/2)
solving this I am getting absurd answer.

 

[Borek]

Check your math.

 

[zorro]

I checked it again. But no error in math. I guess some equations are wrong.

 

[Borek]

Check your check then, I have solved your equation and got the correct answer.

 

[zorro]

Oh yes. Thanks a lot.