Answer
$Kc = [H+][OH-] $
heterogeneous
Work Step by Step
The expression of Kc is the concentration of the products raised to their coefficients divided by the concentration of the reactants raised to their coefficients.
$Kc = [H+][OH-]$
The H2O is omitted since it is a pure liquid
Since we have pure liquids and aqueous solutions, it is heterogeneous