Answer to Question #88505 in General Chemistry for Deepu john

Question

At a certain temperature a saturated solution of Zn(OH)2 has a pH of 8. What is the value of Ksp at this temperature?

Answer 1

pH = 8, C(H⁺) = 10^-8 M.

C(OH^-) = K_w/C(H⁺) = 10^-14/10^-8 M = 10^-6 M.

                   x M     10^-6 M

Zn(OH)₂ ⇄ Zn²⁺ + 2OH^-

                   1 M      2 M

C(Zn²⁺) = x = 10^-6 / 2 M = 0.5 × 10^-6 M.

K_sp = C(Zn²⁺) × [C(OH^-)]² = 0.5 × 10^-6 × (10^-6)² = 0.5 × 10^-18.