Conjugate Acids and Bases

The Acidic Environment‎ > ‎4. Acid/Base Definitions‎ >

Describe the relationship between an acid and its conjugate base and a base and its conjugate acid

Identify conjugate acid/base pairs

  • Conjugate base: The substance formed from an acid when it gives up a proton.
  • The conjugate base of a strong acid is an extremely weak base, which is too weak to react with the solvent.
  • The conjugate base of a weak acid is a weak base.
  • Conjugate acid: The substance formed from a base when it accepts a proton.
  • The conjugate acid of a strong base is an extremely weak acid, which is too weak to react with the solvent.
  • For example, when hydrochloric acid (a strong acid) reacts with water (a weak base), a hydronium ion (a strong conjugate acid) and a chloride ion (a weak conjugate base) are formed:
  • In the above example, hydrochloric acid and the hydronium ion are a conjugate acid-base pair, while water and the chloride ion are another conjugate acid-base pair.