Relative Strengths of Acids and Bases

Acid and Base Ionization Constants

The relative strength of an acid or base is the extent to which it ionizes when dissolved in water. A weaker acid at a certain concentration will have a higher (more neutral) pH than a stronger acid at the same concentration, since fewer molecules of that weaker acid will dissociate. The same is true for weaker and stronger bases.

Some acids and bases will dissociate (ionize) nearly completely in aqueous solution – so that when we have a solution of a strong acid “HA”, we can treat it as completely reacted to produce “H+” and “A” as soon as the solution is formed. These acids and bases are called the strong acids and strong bases. There are only a few commonly used strong acids and bases -the most common strong acids and bases are listed in the table below. Most acids and bases you encounter will be weak – they do not completely dissociate.

Some of the common strong acids and bases are listed here.