The solubility product of a sparingly soluble salt AX2 is 3.2 10-11. Its solubility (in moles/L) is
- 5.6 10-6
- 3.1 10-4
- 2 10-4
- 4 10-4
Answer
(3) 2 10-4
Solution
AX2(s) A2+(aq) + 2X-(aq)
If solubility = s mol/L, then [ A2+] = s and [X-] = 2s
⇒ Ksp = s(2s)2 = 4s3
⇒ 4s3 = 3.2 10-11
⇒ s3 = 8 10-12
∴ s = 2 10-4 mol L-1
Answer: (3)