Classify each acid as strong or weak. If the acid is weak, write an expression for the acid ionization constant (K_a). c. H₂SO₄

Key Concepts

Strong and Weak Acids

Strong acids completely dissociate in water, releasing all their hydrogen ions (H+), while weak acids only partially dissociate. This distinction is crucial for understanding acid behavior in solution, as strong acids have a high concentration of H+ ions, leading to a lower pH, whereas weak acids result in a higher pH due to their incomplete dissociation.

Acid Ionization Constant (Ka)

The acid ionization constant (Ka) quantifies the strength of a weak acid by measuring the extent of its dissociation in water. It is defined by the equilibrium expression: 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.

H2SO4 as a Strong Acid

H2SO4, sulfuric acid, is classified as a strong acid because it completely dissociates in its first ionization step, producing H+ and HSO4-. Although HSO4- can act as a weak acid in its second ionization, the first dissociation is what primarily characterizes H2SO4 as a strong acid, making it essential to recognize its behavior in acid-base reactions.