HClO2, also known as chlorous acid, is not classified as a strong acid in aqueous solution. Instead, it is considered a weak acid. This classification is based on its ability to dissociate in water.
Strong acids completely dissociate into their ions in aqueous solutions, meaning they release all of their hydrogen ions (H+) into the solution. Examples of strong acids include hydrochloric acid (HCl) and sulfuric acid (H2SO4).
In contrast, weak acids like HClO2 only partially dissociate in water. This means that only a small fraction of the HClO2 molecules release their hydrogen ions into the solution. The dissociation of HClO2 can be represented by the following equilibrium equation:
HClO2 ⇌ H+ + ClO2-
Because the dissociation is incomplete, the solution contains a mixture of HClO2 molecules, H+ ions, and ClO2- ions. The extent of dissociation is quantified by the acid dissociation constant (Ka), which is relatively small for weak acids like HClO2.
In summary, HClO2 is classified as a weak acid because it does not fully dissociate in aqueous solution, resulting in a lower concentration of H+ ions compared to strong acids.