Which of the following best defines a strong acid?

A strong acid is best defined as one that completely dissociates into its ions when dissolved in an aqueous solution. This means that when a strong acid is added to water, it breaks apart entirely into hydrogen ions (H⁺) and the corresponding anions, resulting in a high concentration of H⁺ ions in the solution. This complete dissociation is what gives strong acids their characteristic ability to lower pH significantly, making the solution very acidic.

Understanding this concept is crucial in chemistry, particularly in acid-base reactions, as it allows for predictions about the behavior of acids in solution, their reactivity, and their effects on various chemical processes. In contrast, an acid that partially dissociates does not fully release hydrogen ions, which is characteristic of weak acids, while an acid that does not produce hydrogen ions at all does not qualify as an acid in the traditional sense. Likewise, an acid with a low pH might not fully dissociate, indicating it might be behaving like a weak acid.