Question

When the solution above has reached equilibrium, what effect would adding more Mg²⁺ have? Adding more F^-? Why is it that NO MORE PRODUCT forms when more MgF₂ is added to the solution at equilibrium?

Answer 1

Ans:

I imagine the solution equilibrium to be:

Molar concentration of pure solid and pure liquid:

• Density is an intrinsic property - independent of the amount present
• So, molar concentration of pure solid or liquid is constant
• So, [MgF₂(s)] = constant

So, only the change in concentration of Mg²⁺(aq) & change in concentration of F^-(aq) will affect the equilibrium. System equilibrium will not be affected with any amount of MgF₂(s) getting added.

So, for the equilibrium

1. Addition of more of Mg²⁺(aq) will shift the equilibrium to the left according to Le Chatelier’s principle.
2. Addition of more of F^-(aq) will shift the equilibrium to the left according to Le Chatelier’s principle.
3. Addition of MgF₂(s) has no effect on equilibrium according to Le Chatelier’s principle.