Which salts will be more soluble in an acidic solution than in pure water? (in description)

Question

1.) BaSO4

2.) CsClO4

3.) AgI

4.) Zn(OH)2

5.) CaCO3

Answer 1

The salts of a weak acid will be more soluble in acid than the salts of a strong acid when in acidic solution. This is also true of bases. This can be explained by Le Chatelier's principle because when acid is present, the anion of the salt forms a weak acid which does NOT ionize much, thus essentially removing some anion from solution. This shifts the equilibrium to the right, making the salt more soluble.

Example: MA(s) <==> M⁺(aq) + A^-(aq) shows insoluble salt (MA) partially dissolving in absence of acid

MA(s) <==> M⁺(aq) + A^-(aq) + H⁺ ==> M⁺(aq) + HA(aq) shows shift to the right since HA doesn't ionize

Thus, the following should be more soluble in acidic solution:

4) Zn(OH)₂ this is a base

5) CaCO₃ this is the salt of a weak acid (H₂CO₃)

1, 2, and 3 are all salts of strong acids so solubility not affected by pH.