Question

Part B - Calculate the molar solubility in NaOH Based on the given value of the Ksp, what is the molar solubility of Mg(OH)2 in 0.180 M NaOH? Express your answer with the appropriate units. Hints

Answer 1

NaOH -------------> Na^+ (aq) + OH^-

                                0.18M         0.18M

Mg(OH)2 --------------------> Mg^2+ (aq) + 2OH^-

                                                  s                 2s+0.18

   [OH^-] = 2s + 0.18   = 0.18M            [2s <<<<<0.18M]

      Ksp   = [Mg^2+][OH^-]^2

    5.6*10^-11 = s*(0.18)^2

    s = 1.73*10^-9

   solubilit of Mg(OH)2 is 1.73*10^-9 M