In the solubility rules, Mg(OH)2was listed as an “insoluble” salt.
It is actually slightly soluble in anequilibriumreaction:
Mg(OH)2(s) ⇌ Mg2+(aq) + 2OH-(aq)
The equilibrium constant, Ksp, for this reaction at 25oC is 1.2 x 10-11.
What is the equilibrium concentration of Mg2+at 25oC?