Acids, bases, and soluble salts all produce ions in solution; thus they all produce solutions that conduct electricity. All these three types of compounds are said to be electrolytes. An electrolyte is a substance whose aqueous solution conducts electricity.

Some substances, such as table sugar, glucose, and iso-propyl alcohol, do not produce ions in solution. These substances are called non-electrolytes. A non-electrolyte is a substance whose aqueous solution does not conduct electricity.

Electrolytes can be divided into two groups: strong electrolytes and weak electrolytes. A strong electrolyte is a substance that completely (or almost completely) ionizes/dissociates into ions in aqueous solution. Strong electrolytes produce highly conducting solutions. All strong acids, strong bases and all soluble salts are strong electrolytes. A weak electrolyte is a substance that incompletely ionizes/dissociates into ions in aqueous solution. Weak electrolytes produce solutions that are intermediate between those containing strong electrolytes and those containing non-electrolytes. Weak acids and weak bases constitute weak electrolytes.

Figure 1. An arrangement for distinguishing between electrolytes and non-electrolytes
(a) A non-electrolyte solution does not contain ions, and the light bulb is not lit. (b) A weak electrolyte solution contains a small number of ions, and the light bulb is dimly lit. (c) A strong electrolyte
solution contains a large number of ions, and the light bulb is brightly lit.