1. PF Contest - Win "Conquering the Physics GRE" book! Click Here to Enter
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

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!


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


    User Avatar

    Staff: Mentor

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

Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Similar Threads - Equilibrium constant Question Date
Equilibrium constant question? Feb 14, 2011
Chemistry, Equilibrium Constant Question Nov 17, 2010
Chem: Equilibrium Constant Question Jan 31, 2009
Equilibrium constant questions Feb 21, 2008
Tricky equilibrium constant question Feb 4, 2007