Chemistry Equilibrium

Question

A gaseous mixture of NO2 and N2O4 is in equilibrium. If the concentration of N2O4 is 7.1 x 10^-4M what is the concentration of NO2?

2 NO2 = N2O4, Kc= 170

Thank you in advance! If you could explain your work, that would help so so so much.

Answer 1

Start with the base equation of K_c = [products] / [reactants] and since the reactant has a coefficient of 2, we will square the [reactants].

K_c = [N₂O₄] / [NO₂]², and with some rearranging we can equate [NO₂] = sqrt( [N₂O₄] / K_c )

Plug in the numbers from the problem statement and you should get 2.04 * 10^-3 M