The equilibrium expression for the equation, AB (aq) + C (s) ↔ AC (aq) + B (s), is K = [AC]/[AB]

K = [AC]/[AB]

Explanation:

The equilibrium expression is the multiplication of products over the multiplication of reactant if we have a stoichiometric coefficient we need to use raising this number to the concentration.

aA+Bb⇄cC+dD

The expression will be

[C]∧c*[D]∧D/[A]∧a*[B]∧b

In equilibrium the only substant we will use in the equilibrium are the one which is in (aq) state, if the substances are solid is not taking into account.

For gases is:

aA+Bb⇄cC+dD

The expression we use is the following, taking into account pressure.

PC∧c*PD∧D/PA∧a*PB∧b