Classify each acid as strong or weak. If the acid is weak, write an expression for the acid ionization constant (K_a). a. HNO₃

Key Concepts

Strong vs. Weak Acids

Strong acids completely dissociate in water, releasing all their hydrogen ions (H+) and resulting in a high concentration of H+ ions in solution. Examples include hydrochloric acid (HCl) and nitric acid (HNO3). In contrast, weak acids only partially dissociate, establishing an equilibrium between the undissociated acid and its ions, leading to a lower concentration of H+ ions.

Acid Ionization Constant (Ka)

The acid ionization constant (Ka) quantifies the strength of a weak acid in solution. It is defined as the equilibrium constant for the ionization reaction of the acid, represented as Ka = [H+][A-]/[HA], where [H+] is the concentration of hydrogen ions, [A-] is the concentration of the conjugate base, and [HA] is the concentration of the undissociated acid. A larger Ka value indicates a stronger weak acid.

Classification of Acids

Acids are classified based on their ability to donate protons (H+) in solution. Strong acids, like HNO3, are characterized by their complete ionization, while weak acids, such as acetic acid, exhibit partial ionization. Understanding this classification is essential for predicting the behavior of acids in chemical reactions and their impact on pH levels in solutions.