For which salt in each of the following groups will the solubility depend on pH?
Pb(OH)2
PbCl2
Answered above.
Pb(OH)2 because OH- will decrease making equilibrium shift right and then thus increasing solubility
To determine which salt's solubility will depend on pH, you need to consider the formation of hydroxide and chloride ions in water. Let's analyze each salt individually.
1. Pb(OH)2 (Lead(II) hydroxide):
Lead(II) hydroxide (Pb(OH)2) is a sparingly soluble salt. Its solubility depends on the equilibrium between dissolving and precipitating species. In water, Pb(OH)2 dissociates as follows:
Pb(OH)2 ⇌ Pb2+ + 2OH-
The solubility of Pb(OH)2 will depend on the concentration of hydroxide ions (OH-) in the solution. At low pH (acidic conditions), the concentration of OH- ions is low, resulting in low solubility. However, at high pH (basic conditions), the concentration of OH- ions increases, leading to increased solubility.
Therefore, the solubility of Pb(OH)2 is pH-dependent.
2. PbCl2 (Lead(II) chloride):
Lead(II) chloride (PbCl2) is a relatively soluble salt. It dissociates into lead and chloride ions in water:
PbCl2 ⇌ Pb2+ + 2Cl-
The solubility of PbCl2 does not depend on pH. The presence of hydrochloric acid (HCl) can slightly increase the solubility by Le Chatelier's principle, but the overall effect is minimal.
In conclusion, the solubility of Pb(OH)2 (Lead(II) hydroxide) will depend on pH, whereas the solubility of PbCl2 (Lead(II) chloride) does not.