writing a balanced net ionic equation and finding K

Question

Write a balanced net ionic equation to show why the solubility of Pb(OH)2(s) increases in the presence of a strong acid and calculate the equilibrium constant for the reaction of this sparingly soluble salt with acid

 

K=

Answer 1

Take, for example, HCl as the strong acid.

Pb(OH)2(s) + 2H+(aq) + 2Cl-(aq) ==> PbCl2(s) + 2H2O(l)

PbCl2 is much more soluble than Pb(OH)2 so the solubility increases.

Is the question asking for the equilibrium constant for Pb(OH)2 or for PbCl2?

 

Also, this question is ambiguous, because if the strong acid is nitric acid (HNO3), the product, Pb(NO3)2 is soluble.

Pb(OH)2(s) + 2H+(aq) + 2NO3-(aq) ==> 2H2O(l) + Pb2+(aq)  net ionic equation