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Homework Help: Equilibrium constant (K) Question problem

  1. Sep 29, 2010 #1
    Finding the Equilibrium Constant (K)


    I have been having a bit of trouble with this question, if anyone could guide me on where Im going wrong it would be greatly appreciated!



    "Reaction 1: N2 + 3H2 = 2NH3

    Write down an expression for the equilibrium constant K, for reaction 1.
    At 25 degrees Celsius the equilibrium concentrations of N2, H2 and NH3 gases are:

    N2: 1.3 x 10^-3 mol dm^-3
    H2: 1.1 x 10^-2 mol dm^-3
    NH3: 9.8 x 10^-1 mol dm^-3

    Use these values to calculate the value of K at this temperature"





    So then what I did was substitute these values into this equation:

    K = (NH3)^2 / ((N2) x (H2)^3)

    To give this:

    K = (9.8 x 10^-1)^2 / ((1.3 x 10^-3) x (1.1 x 10^-2)^3)

    That then gave me:

    K = 5.6 x 10^8

    Im pretty sure that is not right, Im thinking it should be a lot lot smaller....

    If you could help me out I would appreciate it a lot!

    Thanks

    Danny
     
    Last edited: Sep 29, 2010
  2. jcsd
  3. Sep 29, 2010 #2

    Borek

    User Avatar

    Staff: Mentor

    Agreed that value looks high, but that's what you get from the data given.

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