Question

What does it mean to say that an acid is strong in aqueous solution? What does this reveal about the ability of the acid's anion to attract protons?

Short answer

In an aqueous solution, a strong acid fully dissociates into its ions, producing a high concentration of hydrogen ions (H+ ions), indicating a high degree of acidity. This reveals that the acid's anion (A-) is relatively stable and weakly basic, with a low ability to attract protons, which results in the dissociation reaction equilibrium lying strongly to the right.

Step-by-step solution

Definition of Strong Acid

A strong acid is a substance that completely dissociates into its ions when it is dissolved in water. In other words, when a strong acid is added to an aqueous solution, it ionizes fully to produce a high concentration of hydrogen ions (H+ ions) and its corresponding anion.

Dissociation of Strong Acids in Aqueous Solution

When a strong acid is dissolved in water, it donates protons (H+ ions) to water molecules, which leads to the formation of hydronium ions (H3O+ ions). The chemical equation for the dissociation of a generic strong acid \(HA\) can be written as: \[HA_{(aq)} + H_2O_{(l)} \rightarrow H_3O^+_{(aq)} + A^-_{(aq)}\] In this equation, \(HA\) represents the strong acid, and \(A^-\) is the anion produced by the dissociation of the strong acid.

Acid's Anion and Proton Attraction

The strength of an acid depends on the stability of its anion and its ability to attract protons. For a strong acid, its anion (A-) is relatively stable and weakly basic. This implies that the anion does not readily attract protons from the surrounding solution. In the case of a strong acid, the ability of its anion to attract protons is low. As a result, the equilibrium in the dissociation reaction lies strongly to the right, and the concentration of hydronium ions (H3O+ ions) is high, indicating a high degree of acidity in the solution. In conclusion, saying that an acid is strong in an aqueous solution means that it fully dissociates into its ions and produces a high concentration of hydrogen ions (H+ ions). This phenomenon reveals that the acid's anion has low ability to attract protons, making it relatively stable and weakly basic.