Ammonia, ammonium hydroxide and pyridine are examples of weak chemical bases. A weak base can be identified by the fact that it only partially ionizes when mixed with a water-based solution. The anions of weak acids, which do not fully dissociate from their salts, often form weak bases.
The acidity or basicity of a substance is typically measured by its pH value. Water, which can behave like both an acid and a base, has a pH of 7. Substances with a pH level higher than 7 are bases, with weak bases having a lower pH value than strong bases. As a group, bases are electrolytes and can conduct electricity.