Use Le Châtelier's principle to predict the effect of the following changes on the extent of hydrolysis of sodium nitrite \(\left(\mathrm{NaNO}_{2}\right)\) solution: (a) \(\mathrm{HCl}\) is added, (b) \(\mathrm{NaOH}\) is added, (c) \(\mathrm{NaCl}\) is added, (d) the solution is diluted.

Understanding the hydrolysis of sodium nitrite (\text{NaNO}_2) involves breaking down an ionic compound with water to form an acid and a base. Sodium nitrite, when dissolved in water, equilibrates to form nitrous acid (\text{HNO}_2) and sodium hydroxide (\text{NaOH}). The reaction can be represented as: \[\begin{equation}\text{NaNO}_2(s) + H_2O(l) \rightleftharpoons \text{HNO}_2(aq) + \text{NaOH}(aq).ewlineewlineewline\end{equation}\]ewlineWhen addressing the effects of adding different compounds such as \text{HCl}, \text{NaOH}, \text{NaCl}, or diluting the solution, we can leverage Le Châtelier's principle to predict the shift in equilibrium.

For instance, the addition of a strong acid like \text{HCl} would create an acid-base reaction where \text{HCl} reacts with \text{NaOH}. This decrease in \text{NaOH} concentration could push the equilibrium towards more hydrolysis to compensate, as evidenced in the exercise solution where adding \text{HCl} promotes the hydrolysis process.

Chemical equilibrium is a state in a reversible chemical reaction where the rate of the forward reaction equals the rate of the reverse reaction. As a result, the concentrations of the reactants and products remain constant over time, but not necessarily equal to each other.

Le Châtelier's principle is central to understanding equilibrium shifts. It posits that when a stress is applied to a system at equilibrium, the system will readjust to counteract the stress and reestablish equilibrium.

• Addition of reactants or removal of products usually causes the reaction to proceed in the forward direction.
• Addition of products or removal of reactants usually causes the reaction to proceed in the backward direction.
• Changes in temperature or pressure can also shift the equilibrium depending on the nature of the reaction.

Equilibrium is pivotal in the hydrolysis of sodium nitrite where different agents added to the system induce shifts that affect the extent of hydrolysis.

An acid-base reaction is a chemical reaction that occurs when an acid and a base interact, often resulting in the production of a salt and water. This process is also referred to as neutralization.

In the context of the hydrolysis of sodium nitrite, when \text{HCl} is added to the solution or when dilution occurs, acid-base reactions play a critical role. For example, \text{HCl}, a strong acid, reacts with \text{NaOH}, a base, which forms in the hydrolysis process. This results in the formation of water and sodium chloride (\text{NaCl}). The reaction can be presented as: \[\begin{equation}\text{HCl}(aq) + \text{NaOH}(aq) \rightarrow \text{H}_2\text{O}(l) + \text{NaCl}(aq).ewlineewline\end{equation}\] 

These interactions exemplify an acid-base reaction in a dynamic equilibrium scenario. Consequences of such reactions include changes in pH levels or alteration in the concentration of reactants and products, influencing the position of equilibrium and the extent of chemical reactions like hydrolysis.