What differentiates a strong acid from a weak acid?

The defining characteristic of a strong acid is its ability to completely dissociate in an aqueous solution, meaning that it breaks apart entirely into its constituent ions. This complete dissociation results in a higher concentration of hydrogen ions (H⁺) in the solution, leading to a lower pH. Strong acids, such as hydrochloric acid (HCl), have this property and therefore are highly effective at delivering protons to the solution, resulting in their strong acidic behavior.

In contrast, weak acids do not fully dissociate; they only partially break apart into ions when dissolved in water. This partial dissociation means that a significant amount of the acid remains in its molecular form, resulting in a lower concentration of hydrogen ions compared to strong acids.

Understanding this distinction is crucial for predicting the behavior of acids in chemical reactions and in various applications, such as buffer solutions and titrations.