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Homework Help: What is the degree of dissociation?

  1. Sep 17, 2010 #1
    1. The problem statement, all variables and given/known data

    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?

    2. Relevant equations



    3. 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
     
  2. jcsd
  3. Sep 17, 2010 #2

    Borek

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    Staff: Mentor

    Show more details of your work.
     
  4. Sep 17, 2010 #3
    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.
     
  5. Sep 17, 2010 #4

    Borek

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    Staff: Mentor

    Check your math.
     
  6. Sep 18, 2010 #5
    I checked it again. But no error in math. I guess some equations are wrong.
     
  7. Sep 18, 2010 #6

    Borek

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    Staff: Mentor

    Check your check then, I have solved your equation and got the correct answer.
     
    Last edited by a moderator: Aug 13, 2013
  8. Sep 18, 2010 #7
    Oh yes. Thanks alot.
     
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