pH of a saturated solution of Ca(OH)2 is 9. The solubility product ( Ksp) of Ca(OH)2 is :
- 0.125 10-15
- 0.5 10-10
- 0.5 10-15
- 0.25 10-10
Answer
(3) 0.5 10-15
Solution
pH = 9 ⇒ pOH = 14 − 9 = 5 ⇒ [OH-] = 10-5 M
Ca(OH)2(s) Ca2+(aq) + 2OH-(aq)
⇒ [Ca2+] = [OH-]2 = 0.5 10-5 M
Ksp = [Ca2+][OH-]2
= (0.5 10-5)(10-5)2
= 0.5 10-15
Answer: (3)