Question

The solubility of CaF2 (Ksp = 3.4 × 10–11) in 0.1 M solution of NaF would be

• A. 3.4 × 10–12 M
• B. 3.4 × 10–10 M
• C. 3.4 × 10–9 M
• D. 3.4 × 10–13 M.

Answer 1

Answer: (C)

3.4 × 10–9 M

Answer 2

(1) NaF $\longrightarrow$ Na+ + F–

0.1 0.1 0.1

CaF2 $\longrightarrow$ Ca2+ + 2F–

(2x + 0.1) 0.1

Ksp = x (0.1)2 = 3.4 × 10–11 x = 3.4 × 10–9