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Homework Help: Compare a system to equilibrium

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  1. May 12, 2007 #1
    1. The problem statement, all variables and given/known data
    Determine whether or not each of the following system is in equilibrium. If the system is not in equilibrium, predict whether it will proceed in the forward or reverse direction:
    2 H2(g) + O2(g) ---> 2H2O(g)
    and Kc (equilibrium constant) is 9.1 x 10^80
    and the concentrations are H2: 3 x 10^-30 M...for O2: 2.2 x 10^-24...for 2H2O: 0.0180 M

    2. Relevant equations
    To compare a system to equilibrium, you have to compare K to Q. where Q is [products]^coeffecients / [reactants]^coeffecients
    and if Q = K, the reaction is at equilibrium...if Q < K, the reaction will move in the forward direction...and if Q > K, the reaction will move in the reverse direction.

    3. The attempt at a solution
    so i solved it like this...
    [0.0180]^2 / [3 x 10^-30]^2[2.2 x 10-24] and i got...1.64 x 10^79 for Q
    and since Q < K i said the reaction would move in the forward direction

    and here's where the problem comes in :yuck:
    the book says: that for Q i should get 9.1 x 10^80, meaning that Q would be equal to K and reaction would be in equilibrium.

    please help me. am i inputing the things in my calculator wrong? or is the book wrong? thanks muchhh :biggrin:
    Last edited: May 13, 2007
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  3. May 13, 2007 #2
    come on guysssssss.
    you can do this.
  4. May 13, 2007 #3


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    Homework Helper

    Well, I'm no chemist, but I think your calculation for Q is correct. I can't see a mistake in it. Are you sure you copied everything correctly? Perhaps the book is wrong.
  5. May 13, 2007 #4

    i'm positive i copied everything correctly.&i did it like 10 times.
    so the book is probably wrong.
    thanks so much hage657 :tongue:
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