Show by suitable net ionic equations that each of the following species can act as a Bronsted-Lowry base: (a) \(\mathrm{HS}^{-}\) (b) \(\mathrm{PO}_{4}^{3-}\) (c) \(\mathrm{NH}_{2}^{-}\) (d) \(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}\) (e) \(\mathrm{O}^{2-}\) (f) \(\mathrm{H}_{2} \mathrm{PO}_{4}^{-}\)

Net ionic equations are a cornerstone of understanding reactions in chemistry, particularly when studying acids and bases. They show the actual chemical species that are involved in a reaction, excluding the spectator ions that do not participate.
When writing net ionic equations for a Bronsted-Lowry base, the focus is on how these bases accept protons. These equations are invaluable in visualizing the role of a base in an acid-base reaction. This simplification allows students to see the essential players in the reaction without the potential confusion of unnecessary components.

• Representing the Reaction: A base (B) receives a proton (H+) from an acid (HA) to form its conjugate acid (BH+). This can be represented as: \[ B + H^+ \rightarrow BH^+ \]
• Example with Phosphate: Taking the phosphate ion (\(\mathrm{PO_4^{3-}}\)) as an example, the net ionic equation presented in the solution: \[ \mathrm{PO_4^{3-}} + H^+ \rightarrow \mathrm{HPO_4^{2-}} \] clearly depicts the acceptance of a proton by the phosphate ion, turning it into its conjugate acid.

These equations not only affirm the reactivity of species but also prepare students for more complex reaction stoichiometry.

In the context of Bronsted-Lowry acid-base chemistry, proton acceptance is the process by which a base accepts a proton (H+). It is the defining action of bases under this theory.
The species that donates the proton is the acid, and the one that accepts is the base. When teaching proton acceptance, it's important to show that the gained proton changes the base.

• Defining a Base: A base is, therefore, any substance that can accept a proton, as illustrated in the exercise problems where ions, like \(\mathrm{HS^-}\) and \(\mathrm{NH_2^-}\), and molecules like ethanol (\(\mathrm{C_2H_5OH}\)) are shown gaining a proton.
• Reactant to Product: With proton acceptance, a new substance is formed—this is the conjugate acid of the base. For instance, when ammonia (\(\mathrm{NH_2^-}\)) accepts a proton, it becomes ammonium (\(\mathrm{NH_3}\)).

In providing assistance, it's crucial to remind learners that the ability of different species to accept protons can vary widely, which translates to their varying basic strengths.

When tackling acid-base reactions, it's essential to understand conjugate acid/base pairs. These pairs are products of a Bronsted-Lowry acid-base reaction—a base gains a proton and becomes an acid, while an acid loses a proton and becomes a base.

• Understanding the Pair: Consider hydroxide (\(\mathrm{OH^-}\)) accepting a proton to become water (\(\mathrm{H_2O}\)). Here, \(\mathrm{OH^-}\) and \(\mathrm{H_2O}\) are a conjugate base and its acid pair, respectively.
• Relevance to Equations: Conjugate pairs are especially important when interpreting net ionic equations. For example, in the solution for \(\mathrm{O^{2-}}\), the equation \(\mathrm{O^{2-}} + H^+ \rightarrow \mathrm{OH^-}\) shows \(\mathrm{O^{2-}}\) transforming into its conjugate acid \(\mathrm{OH^-}\).

By studying pairs, students can predict the results of reactions and understand the nature of substances in various chemical environments.

Acid-base chemistry is a fundamental concept that accounts for a broad spectrum of chemical reactions in various fields, from environmental science to medicine. It is anchored around the transfer of protons from acids to bases.

• Understanding Acidity/Basicity: The strength of an acid or a base refers to its propensity to lose or gain a proton, respectively. Substances like \(\mathrm{HCl}\) (a strong acid) readily donate protons, while \(\mathrm{NH_3}\) (a weak base) more reluctantly accepts them.
• pH Scale: The pH scale quantifies the acidity or basicity of a solution, crucial for predicting the behavior of molecules in that solution.

Teaching acid-base chemistry involves explaining these principles, as well as guiding students through the interpretation of various scenarios where these principles apply. Through this understanding, learners become adept at predicting the direction and products of acid-base reactions.