Question

In the equilibrium constant expression for the reaction below what is the correct exponent for N2O4?

Answer 1

As we have the balanced reaction equation is:

N2O4 (g) ↔ 2NO2(g)

from this balanced equation, we can get the equilibrium constant expression

KC = [NO2]^2[N2O4]^1

from this expression, we can see that [NO2 ] is with 2 exponent of  the stoichiometric and we can see that from the balanced equation as NO2
is 2NO2 in the balanced equation.

and [N2O4] is with 1 exponent of the stoichiometric and we can see that from the balanced equation as N2O4 is 1 N2O4 in the balanced equation. 

∴ the correct exponent for N2O4 in the equilibrium constant expression is 1