A weak acid is an acid that does not completely dissociate (break apart) into ions when dissolved in water. Instead, it only partially releases hydrogen ions (H⁺), and most of the acid molecules remain undissociated.
- In water, a weak acid establishes an equilibrium between the undissociated acid molecules and the ions it produces.
- This means only a small fraction of molecules donate protons (H⁺) to the solution.
- As a result, weak acids produce a lower concentration of H⁺ ions compared to strong acids at the same concentration.
- Their solutions usually have a pH greater than strong acids of the same molar concentration.
Examples of weak acids:
- Acetic acid (vinegar)
- Carbonic acid
- Phosphoric acid
- Hydrofluoric acid
In short: A weak acid is one that partially ionizes in water, making it less acidic than a strong acid of the same concentration.