A weak electrolyte is a substance which forms ions in an aqueous solution but does not dissociate completely. When dissolved, a weak electrolyte does not disperse completely into ions. The solution instead contains both ions and molecules. Some examples of weak electrolytes are carbonic acid, acetic acid and ammonia.
A weak electrolyte usually only has an ionization percentage between 1 to 10 percent. This means that the larger part of the electrolyte is an un-ionized compound or molecule that stays the same even when dissolved in water. Weak electrolytes are either weak acids or weak bases. Phosphoric acid and hydrofluoric acid are weak acids, while ammonia and pyridine are weak bases.