Substances that can be electrolised:
- Ionic substances soluble in water, salts, hydroxides, etc.
- Covalent compounds that release ions in solutions (acids)
Ionic substances
Ionic substances are composed by a metal and a non-metal (NaCl, CuCl2, etc.) or a metal and a group of nonmetals (CuSO4, NaOH, etc.)
Ionic substances contain ions. If we analyze sodium chloride, Sodium ions (Na+) and Chloride ions (Cl–) are present. Hence, sodium chloride could be broken down by the use of electricity.
We saw that ionic compounds only carry electricity if molten or dissolved in water, so in order for electrolysis to work, the ions need to be free, hence the substance has to be molten or dissolved in water.
In our example, Sodium ions and Chloride ions will travel through the liquid and Sodium would be deposited in one of the electrodes and Chlorine gas will be bubbling in the opposite electrode.
What happens during the electrolysis: