Show by suitable net ionic equations that each of the following species can act as a Bronsted-Lowry acid: (a) \(\mathrm{HNO}_{3}\) (b) \(\mathrm{PH}_{4}^{+}\) (c) \(\mathrm{H}_{2} \mathrm{S}\) (d) \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{COOH}\) (e) \(\mathrm{H}_{2} \mathrm{PO}_{4}^{-}\) (f) HS \(^{-}\)

Net ionic equations are a fundamental concept in chemistry, simplifying reactions to show only the species that actually participate in the chemical process. These equations strip away spectator ions, which do not contribute to the overall reaction, to focus on the action at the core of the reaction.

To illustrate, let's look at an acid-base reaction featuring a Bronsted-Lowry acid. In every instance, you will notice that the equation highlights the transfer of protons (\textup{H}^+) between molecules or ions. The full molecular equation might list all reactants and products, including those that remain unchanged, but the net ionic equation only shows the active participants.

For example, when \textup{HNO}_3 acts as a Bronsted-Lowry acid, it donates a proton, and this pivotal moment is captured succinctly as: \[ \textup{HNO}_3 + \textup{H}_2\textup{O} \rightarrow \textup{H}_3\textup{O}^+ + \textup{NO}_3^- \]
Net ionic equations are crucial in understanding the essence of chemical reactions and figuring out how substances transform and interact on the ionic level.

The concept of proton donation lies at the heart of the Bronsted-Lowry theory of acids and bases. In this theory, an acid is defined by its ability to donate a proton, which is simply a hydrogen ion (\textup{H}^+), to another substance. This is a central notion in understanding acid-base chemistry.

When a substance like \textup{PH}_4^+ donates a proton, it undergoes a transformation, illustrating the Bronsted-Lowry theory in action. The proton donor becomes a different species altogether after the proton transfer: \[ \textup{PH}_4^+ \rightarrow \textup{H}_2 + \textup{PH}_3\]
Each acid listed in the exercise showcases this characteristic of proton donation, a paradigm shift from just considering the presence of hydrogen to focusing on the dynamic exchange of protons in acid-base reactions. This in-depth understanding is crucial for students to master the underlying principles of acidity and reactivity in chemistry.

An acid-base reaction is a process where an acid and a base interact, typically resulting in the formation of a salt and water, and is a quintessential part of chemical reactions. In the Bronsted-Lowry perspective, such reactions are viewed through the transfer of protons. Acids donate protons, while bases accept them.

For each compound provided in the exercise, we can infer its behavior in an aqueous solution. For example, \textup{H}_2\textup{S} is an acid because it donates a proton, leading to this net ionic equation: \[ \textup{H}_2\textup{S} \rightarrow \textup{H}^+ + \textup{HS}^-\]
An acid-base reaction is thus not just a mixing of substances but a complex dance of proton transfers that redefines the interacting entities. Recognizing these transformations helps students predict the outcomes of chemical reactions and grasp the nuanced roles substances play beyond their initial definitions as mere acids or bases.