[Phoenix]

In an experiment, 9.0 moles of nitrogen and 27 moles of hydrogen were placed into a vessel of volume 10 dm3 and allowed to reach equilibrium. It was found that two thirds of the nitrogen and hydrogen were converted into ammonia. Calculate Kc for the reaction.
      N2(g) + 3H2(g) == 2NH3(g)

How is the answer 6.6mol -2 dm6?

Tried calculating changes in equilibrium then dividing mol by reaction vessel to find Kc using the Kc expression. I had no  success.

[Borek]

Please don't cross post.

Locked here.