Solubility of calcium phosphate (molecular mass, M) in water is W g per 100 mL at 25 . Its solubility product at 25 will be approximately.
- 107 ( WM )3
- 103 ( WM )5
- 107 ( WM )5
- 105 ( WM )5
Answer
(3) 107 ( WM )5
Solution
Ca3(PO4)2(s) 3Ca2+(aq) + 2PO43-(aq) ⇒ ion concentrations 3s and 2s
Ksp = (3s)3(2s)2 = 108 s5
W g in 100 mL ⇒ s = WM 1000100 = 10 ( WM ) mol L-1
⇒ Ksp = 108 105 ( WM )5
= 1.08 107 ( WM )5 107 ( WM )5
Answer: (3)