
Our AP Chem class has been given an equilibrium
problem using the ICE method. We have worked out
the answer, but compared to the supplied "correct
answer" are coming up doubled...Can you help us
understand where we have gone wrong? PROBLEM:
Find the K for the reaction: 2 CO(g) +
O_{2}(g) <> 2 CO_{2}(g) if
initially there are 5.0 moles of CO, 10.0 moles of
O_{2}, and 1.0 mole of CO_{2} in a
2.0 L container and at equilibrium CO_{2}
has a concentration of 2.5 mol/L. When working the
ICE, we determine that x = 1 which when plugged
back into the Kc expression gives us (2.5)squared
over [(.5)squared times 4]. This gives us a Kc
value of 6.25 but our answer key tells us that
the answer should be 3.125. We are wondering,
isn't the K value independent of the number of
liters, and thus our answer should not be divided
by 2? Where are we going wrong? Thanks for your
chemical knowledge and willingness to share! 
Question Date: 20170406   Answer 1:
I do know that both O_{2} and CO are
pretty reactive, and that CO_{2} is not,
so I would think that the equilibrium would
strongly favor the CO_{2} over the
O_{2} and CO. I don't know how your
numbers will work, though.
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