# How would you use Le Chatelier's principle to predict whether the solubility of BaF_2 will increase, decrease, or remain the same on addition of each of the following substances?

## $H C l$ $K F$ $N a N {O}_{3}$ $B a {\left(N {O}_{3}\right)}_{2}$

Nov 14, 2016

We examine the solubility equilibrium:

$B a {F}_{2} \left(s\right) r i g h t \le f t h a r p \infty n s B {a}^{2 +} + 2 {F}^{-}$

#### Explanation:

Addition of $H C l$ would protonate ${F}^{-}$, and drive equilibrium to the right, i.e. bring more of the fluoride into solution.

Addition of soluble $K F$ increases ${F}^{-}$, and equilibrium is driven to the left.

Addition of sodium nitrate, should have no effect.

And, clearly, addition of soluble barium nitrate should drive equilibrium to the left (by increasing $\left[B {a}^{2 +}\right]$), and barium fluoride should precipitate.