Answer:-
10.0
Explanation: -
The equation is
N2O4 = 2NO2.
Concentration of NO2 = [NO2} = 0.500 M
Concentration of N2O4 = [N2O4] = 0.0250 M
Keq is the equilibrium constant.
It is the ratio of the concentration of products raised to the stoichiometric coefficient of the product to the concentration of the reactants raised to the stoichiometric coefficient of the reactants.
The expression for Keq = [NO2] ^2 / [N2O4]
= 0.500^2 / 0.0250
= 10.0