What is the molar solubility of Mg(OH)₂ in a basic solution with a pH of 12.50? K_spfor Mg(OH)₂ is A) 1.8 × 10^-¹⁰ mol L^-1 B) 5.6 × 10^-⁹ mol L^-1 C) 2.4 × 10^-6 mol L^-1 D) 1.1 × 10^-4 mol L^-1

Question

Quizplus · Accepted Answer

The first step is to write the balanced equation for the dissolution of Mg(OH)2 in water: Mg(OH)2(s) <=> Mg2+(aq) + 2OH-(aq) The equilibrium constant expression for this reaction is: Ksp = [Mg2+][OH-]^2 Since the solution is basic, we can assume that all the OH- comes from the dissociation of water: OH-(aq) + H2O(l) <=> H3O+(aq) + OH-(aq) Kw = [H3O+][OH-] = 1.0 x 10^-14 pH = 12.50 implies [H3O+] = 10^-12.50 = 3.16 x 10^-13 M Thus: [OH-] = Kw/[H3O+] = 3.16 x 10^-14 M Substituting these values into the expression for Ksp and solving for [Mg2+]: Ksp = [Mg2+][OH-]^2 1.1 x 10^-11 = [Mg2+](3.16 x 10^-14)^2 [Mg2+] = 5.6 x 10^-10 M The molar solubility of Mg(OH)2 in this solution is equal to the concentration of Mg2+: mol solubility = 5.6 x 10^-10 M Therefore, the best choice is B.

What Is the Molar Solubility of Mg(OH)2 in a Basic

What Is the Molar Solubility of Mg(OH)₂ in a Basic