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?

#HCl#
#KF#
#NaNO_3#
#Ba(NO_3)_2#

1 Answer
Nov 14, 2016

Answer:

We examine the solubility equilibrium:

#BaF_2(s) rightleftharpoons Ba^(2+) + 2F^-#

Explanation:

Addition of #HCl# would protonate #F^-#, and drive equilibrium to the right, i.e. bring more of the fluoride into solution.

Addition of soluble #KF# 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 #[Ba^(2+)]#), and barium fluoride should precipitate.