Final answer:
The solubility of compounds that are salts of conjugate bases of weak acids increases with increasing solution acidity, due to acids reacting with the anions and thus driving the dissolution equilibrium forward. No change in solubility occurs for salts of strong acids, while the common ion effect can reduce solubility in some cases.
Step-by-step explanation:
The solubility of compounds can be affected by the acidity of the solution. When the acidity increases, compounds that are salts of conjugate bases of weak acids generally have increased solubility. This is because the additional acid reacts with the anions of these weak bases, diminishing their concentration in solution and driving the dissolution equilibrium forward to increase solubility. For example, when considering the solubility of compounds in a more acidic solution:
- NiCO3 will have increased solubility because CO32- is the conjugate base of a weak acid (carbonic acid).
- Compounds like Zn(NO3)2 will have unchanged solubility as NO3-, being the conjugate base of a strong acid (nitric acid), is not affected by changes in pH.
- Salt compounds such as NH3 will also have increased solubility due to NH3 being the conjugate base of a weak acid.
The common ion effect also influences solubility. For instance, adding MgCl2 to a saturated solution of Mg(OH)2 will decrease the solubility of Mg(OH)2 since the concentration of the common ion (Mg2+) increases. Additions like KOH, a strong base, will significantly reduce the solubility of acidic salts as it increases pH and suppresses the ionization of weak acids.