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 5.61 × 10^-12. A)1)8 × 10^{- 10} M B)5)6 × 10^{- 9} M C)2)4 × 10^-6 M D)1)1 × 10^-4 M

Question

Quizplus · Accepted Answer

First, we need to write out the balanced equation for the dissolution of Mg(OH)2:
Mg(OH)2(s) <=> Mg2+(aq) + 2OH-(aq)

The Ksp expression for this reaction is: Ksp = [Mg2+][OH-]2 = 5.61 × 10-12

In a basic solution with a pH of 12.50, we know that [OH-] = 10-pH = 3.16 × 10-3 M

Since the stoichiometry between Mg2+ and OH- in the balanced equation is 1:2, the equilibrium concentration of Mg2+ will be half of the equilibrium concentration of OH-: [Mg2+] = 1.58 × 10-3 M

Therefore, the molar solubility of Mg(OH)2 is 1.58 × 10-3 M, which is closest to choice B (5.6 × 10-9 M).

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

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