BaCl2(aq) + Na2SO4(aq) ⇄ 2NaCl(aq) + BaSO4(s)
Consider the chemical reaction represented above. What will be the resulting change if more barium chloride is added to the system?
A) There will be no change.
B) The equilibrium will change in both directions.
C) The equilibrium will shift to the left and the precipitate will dissolve.
D) The equilibrium will shift to the right and more precipitate will be formed.

Le Châtelier's principle states that when there is an dynamic equilibrium, and this equilibrium is disturbed by an external factor, the equilibrium will be shifted in the direction that can cancel the effect of the external factor to reattain the equilibrium.

For the reaction:

BaCl₂(aq) + Na₂SO₄(aq) ⇄ 2NaCl(aq) + BaSO₄(s)↓,

Adding more BaCl₂ to the system:

will increase the concentration of BaCl₂ (reactants), so the equilibrium will be shifted to the right side (products side) to suppress the effect of increasing the BaCl₂.

So, the right choice is:

D) The equilibrium will shift to the right and more precipitate will be formed.