Answer
$$K_c = \frac{[HCN][OH^-]}{[CN^-]} $$
Work Step by Step
$$K_c = \frac{[Products]}{[Reactants]}$$
$$K_c = \frac{[HCN][OH^-]}{[CN^-]} $$
** Since $H_2O$ is a pure liquid, we do not put it in the equation for $K_c$.
You can help us out by revising, improving and updating this answer.
Update this answerAfter you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.