What is the solubility of Mg(OH)₂ at a pH of 12.00? (Ksp Mg(OH)₂ is 1.6 × 10⁻¹³)

Question

What is the solubility of Mg(OH)₂ at a pH of 12.00? (Ksp Mg(OH)₂ is 1.6 × 10⁻¹³)

Answer 1

Mg(OH)₂(s) <==> Mg²⁺(aq) + 2OH^-(aq)

Ksp = 1.6x10^-13 = [Mg²⁺][OH^-]²

pH = 12

pOH = 2

[OH-] = 1x10^-2 M

1.6x10^-13 = [Mg²⁺][1x10^-2]²

[Mg²⁺] = 1.6x10^-9 M = solubility of Mg(OH)₂ at pH 12