Specify which of the following salts will undergo hydrolysis: \(\mathrm{KF}, \mathrm{NaNO}_{3}, \mathrm{NH}_{4} \mathrm{NO}_{2}, \mathrm{MgSO}_{4}, \mathrm{KCN}\) \(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{COONa}, \mathrm{RbI}, \mathrm{Na}_{2} \mathrm{CO}_{3}, \mathrm{CaCl}_{2}, \mathrm{HCOOK}\).

Chemical equilibrium is a state in a chemical reaction where the rate of the forward reaction equals the rate of the reverse reaction, so the concentrations of reactants and products remain constant over time. In the context of salt hydrolysis, which involves an acid-base reaction taking place in solution, the equilibrium concept is critical.

When salts dissolve in water, they may interact with the water molecules in a reversible manner, leading to the formation of the acid and base from which they were derived. The point at which the rates of hydrolysis (the breakdown of a compound due to reaction with water) and the reverse reaction are equal marks the equilibrium state. Understanding this concept helps explain why certain salts, depending on their origins from strong or weak acids and bases, either hydrolyze or remain stable in aqueous solutions.

Acid-base reactions involve the exchange of protons between chemical species. Hydrolysis of salts in water typically results in an acid-base reaction, where the cation or anion (or both) of the salt react with water to generate an acid or a base.

For instance, when ammonium nitrite \( \mathrm{NH_{4}NO_{2}} \) is dissolved in water, it can react to form \( \mathrm{HNO_{2}} \) and \( \mathrm{NH_{3}} \) because it's formed from a weak acid and a weak base. An important point to remember is that salts derived from a strong acid and a strong base, such as sodium nitrate \( \mathrm{NaNO}_{3} \) or calcium chloride \( \mathrm{CaCl}_{2} \), won't typically hydrolyze because they are stable in their ionic form in aqueous solution. By recognizing the components that make up a salt, we can predict the potential for hydrolysis and the resulting pH change in the solution.

Aqueous solution chemistry deals with chemical reactions and substances dissolved in water. It is essential for understanding how salts behave when they are dissolved. Solubility, ionization, and the resulting reactions in water are all key aspects of this topic.

In the exercise, identifying whether salts will undergo hydrolysis involves knowing how the ions from the salt will interact with water. Salts like potassium fluoride (KF) that come from the neutralization of a strong base by a weak acid will generally not hydrolyze because the strong base component (KF) will not react further with water. On the other hand, salts that are a product of a weak acid and weak base, such as ammonium nitrite (NH4NO2), will hydrolyze, which changes the pH of the solution because ions from these salts readily react with water to produce acidic or basic solutions. This information is incredibly valuable when predicting the behavior of ions in biological, environmental, and industrial processes.