Answer
$Kc = [H+][OH-]$
heterogeneous
Work Step by Step
The expression for Kc is given by the concentration of the products raised to their stoichiometric coefficients divided by the concentration of the reactants raised to their coefficients.
$Kc = [H+][OH-]$
There is no denominator because the only reactant is H2O (l) and we cannot have the concentration of a pure liquid.
Since there are both liquids and aqueous solutions it is heterogeneous.