Acid Dissociation Constant (Ka) Definition, Types, Examples & Uses

Acid Dissociation Constant (Ka)

Subject: Chemistry

Book: General Chemistry

Ka measures the strength of a weak acid by expressing the equilibrium constant for HA ↔ H+ + A–. A larger Ka indicates a stronger acid (more dissociation). pKa is –log(Ka), providing a convenient scale. For instance, acetic acid has a Ka of ~1.8×10–5 (pKa = 4.76). Ka values guide buffer design, acid–base titrations, and understanding biological acid–base homeostasis.