Like water, liquid ammonia undergoes autoionization: $$ \mathrm{NH}_{3}+\mathrm{NH}_{3} \rightleftharpoons \mathrm{NH}_{4}^{+}+\mathrm{NH}_{2}^{-} $$ (a) Identify the Brønsted acids and Brønsted bases in this reaction. (b) What species correspond to \(\mathrm{H}^{+}\) and \(\mathrm{OH}^{-}\) and what is the condition for a neutral solution?

The Brønsted-Lowry theory provides a foundational concept for understanding acids and bases which is vital for identifying the behavior of substances in various chemical reactions. According to this theory, an acid is defined as a substance that is capable of donating a proton (hydrogen ion, \(H^+\)), and a base is a substance capable of accepting a proton. This proton transfer is the core of acid-base reactions.

For instance, in the autoionization of liquid ammonia (NH_3tag{4901}), each ammonia molecule can both accept and donate a \(H^+\) ion depending on the situation. This flexibility is crucial because it allows substances to behave as either an acid or a base within different chemical contexts. Recognizing this dual capability is essential when dissecting chemical reactions, and understanding the nature of the substances involved.

Liquid ammonia (NH_3tag{4901}), a common household chemical and vital industrial reagent, demonstrates dual behavior under the Brønsted-Lowry theory. Considering its autoionization, \(NH_3\) molecules interact with each other, with one molecule acting as a Brønsted acid and another as a Brønsted base.

During this process, the Brønsted acid version of ammonia donates a proton, resulting in the formation of an \(NH_2^-\) ion. Conversely, as a Brønsted base, an ammonia molecule accepts a proton to form an \(NH_4^+\) ion. This reversible reaction provides a clear example of ammonia's amphiprotic nature -- the ability to either donate or accept protons, which enables it to self-ionize just like water does.

The equilibrium dynamics of the autoionization reaction of ammonia define the conditions for a neutral solution. In a manner analogous to water's autoionization, where neutrality is managed by the equal concentrations of \(H^+\) and \(OH^-\) ions, a neutral solution in saturated liquid ammonia is achieved when the concentrations of the Brønsted acid (NH_4^+tag{4903}) and the Brønsted base (NH_2^-tag{4904}) are equal.

This state of equilibrium suggests a balanced state where neither acidic nor basic species dominate, thus characterizing a neutral solution. For liquid ammonia, achieving neutrality means that the quantities of \(NH_4^+\) ions (analogous to \(H^+\)) and \(NH_2^-\) ions (analogous to \(OH^-\)) must be in perfect balance. Understanding this condition is crucial for manipulating the acidity or basicity of ammonia solutions in various chemical applications.