Acids and bases are classified as being either 'strong' or 'weak'. Strong acids and bases will completely dissociate/ionise in solution.

The general formula for the hydrolysis (reaction with water) of a strong acid is given by...

The general formula for the hydrolysis of a strong base is given by...

Examples of strong acids include hydrochloric acid, nitric acid, and sulfuric acid. Examples of strong bases include sodium hydroxide, potassium hydroxide, and lithium hydroxide.

Weak acids will only partially dissociate/ionise in solution...

The same is true for weak bases…

Examples of weak acids include ethanoic (acetic) acid, hydrofluoric acid, and sulfurous acid. Examples of weak bases include ammonia, alumninium hydroxide, and iron hydroxide.

The strength of an acid is indicated by what is called an acidity constant. The strength of a base is indicated by what is called a basicity constant. Both of these measures of acid/base strength have the same definition as the equilibrium constant.

For example, the acidity constant for an acid at a given temperature is given by...

Similarly, the basicity constant for a base at a given temperature is given by...

The larger the acidity/basicity constant, the stronger the acid/base. For strong acids/bases, the acidity/basicity constant is undefined. This is because strong acids and bases completely dissociate, meaning that [HA] and [B] will be zero (and anything divided by zero is undefined).