Question

What is the molarity of $F^{-}$ ions in a saturated solution of $Ba{F}_2$?
$(K_{sp}=1.0\times {10}^{-6})$

• A. $1.0\times {10}^{-2}$
• B. $1.0\times {10}^{-3}$
• C. $1.26\times {10}^{-2}$
• D. $6.3\times {10}^{-3}$

Answer 1

The correct option is A $1.0\times {10}^{-2}$

Given $K_{sp}=1\times {10}^{-6}$

When $Ba{F}_2$ is dissolved then

$Ba{F}_2⟶B{a}^{+2}+2F^{-}$

$K_{sp}=\left[B{a}^{+2}\right][F^{-}{]}^2$

The molar solubility of atoms over the solution is same. Let it be $S$

${10}^{-6}=S\cdot S^2$

${10}^{-6}=S^3$

$S={10}^{-2}$

Molar solubility gives molarity.

So, molarity of $F^{-}$ is ${10}^{-2}=1.0\times {10}^{-2}$