Question

The solubility of $Ca{F}_2$ is $2\times {10}^{-4}$ mole/litre. Its solubility product is:

• A. $2.0\times {10}^{-4}$
• B. $4.0\times {10}^{-8}$
• C. $8.0\times 8.0\times {10}^{-12}$
• D. $3.2\times {10}^{-11}$

Answer 1

The correct option is C $8.0\times 8.0\times {10}^{-12}$

We have

$Ca{F}_2\to C{a}^{2+}+2F^{-}$

$K_w$ = $4S^3$

$K_w=4\ast (2\ast {10}^{-4}{)}^3$

$K_w$= $4\times 8\times {10}^{-12}$