posted by Zander .
Mg(OH)2(aq) <--> Mg2+ (aq) + 2OH-(aq)
a) what would happen to the equilibrium if some acid is added to the soultuion?
b) what would happen to the solubility of Mg(OH)2?
c) what would happen to the Ksp?
Le Chatelier's Principle says that a system at equilibrium (this is at equilibrium) will shift so as to UNDO what we do to it.
So if you add acid, that H^+ combines with the OH^-, that reduces the OH^- (because H2O is formed) and reducing OH^- means the reaction will increase OH (since we took it away) and the only way OH can be increased is for the rxn to move to the right. That will happen. Now you do the other two.