HNO3, or nitric acid, is classified as a strong acid. This classification is based on its ability to completely dissociate in water, releasing a significant amount of hydrogen ions (H+). When HNO3 is dissolved, it ionizes completely into H+ and NO3– ions.
A strong acid is defined by its complete ionization in aqueous solution, which leads to a low pH. In contrast, weak acids only partially dissociate, resulting in a higher pH level. Examples of weak acids include acetic acid (CH3COOH), which does not fully ionize in water.
Since HNO3 does not have any significant equilibrium between the undissociated acid and its ions in solution, it firmly fits the definition of a strong acid. This property makes it a powerful reagent in chemical reactions, particularly in processes such as nitration and as a strong oxidizing agent.