Question

Which of the following slightly soluble compounds has a solubility greater than that calculated from its solubility product because of hydrolysis of the anion present: AgCl, BaSO4, CaF2, Hg2I2, MnCO3, and ZnS?

a) AgCl
b) BaSO4
c) CaF2
d) Hg2I2

Answer 1

The solubility of MnCO3 is greater than that calculated from its solubility product due to the hydrolysis of the carbonate anion when dissolved in water.

Step-by-step explanation:

In the context of slightly soluble compounds, the solubility can be greater than that predicted by the solubility product (Ksp) if the anion undergoes hydrolysis once the compound is dissolved in water. This hydrolysis can lead to the formation of weak acids or bases, which don't fully dissociate, thereby pulling the dissolution equilibrium forward and increasing solubility.

For the compounds listed (AgCl, BaSO4, CaF2, Hg2I2, MnCO3, and ZnS), the one known to undergo significant hydrolysis of the anion in water, leading to greater solubility than predicted from its Ksp is MnCO3. Carbonates (CO32-) can react with water to form bicarbonate (HCO3-) and carbonate ions, thereby removing CO32- from the solution and shifting the equilibrium to dissolve more MnCO3.