pH of a saturated solution of Ca(OH)2 is 9. The solubility product (Ksp) of Ca(OH)2 is

Question : pH of a saturated solution of Ca(OH)₂ is 9. The solubility product (K_sp) of Ca(OH)₂ is :

(1) 0.5 x 10^-15

(2) 0.25 x 10^-10

(3) 0.125 x 10^-15

(4) 0.5 x 10^-10

answer : from all above options the correct answer is “(1) 0.5 x 10^-15”

solution of question is given below –

We know pH + pOH = 14

Therefore , 9 + pOH = 14

→ pOH = 5

→ [OH^–] = 10^-5

The reaction involved is Ca(OH)₂ ⇌ Ca²⁺ + 2OH^–

Also , [Ca²⁺] = 10^-5/2

K_sp = [Ca²⁺] [OH^–]

= (10^-5/2) (10^-5)² = 0.5 x 10^-15

that is why we have marked option (1) for correct answer.