SbistudyQuestion : pH of a saturated solution of Ca(OH)2 is 9. The solubility product (Ksp) 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
Ksp = [Ca2+] [OH–]
= (10-5/2) (10-5)2 = 0.5 x 10-15
that is why we have marked option (1) for correct answer.