How is electrolysis used in the extraction of metals?

Electrolysis is used in the extraction of metals from their ores through a process called electrorefining.

In the extraction of metals, electrolysis is a fundamental process that involves the use of an electric current to drive a non-spontaneous chemical reaction. This process is particularly important in the extraction of metals from their ores, especially for those metals that are too reactive to be reduced by carbon, such as aluminium and sodium.

The process begins with the ore being crushed and heated to convert it into a molten state. This molten ore, also known as an electrolyte, is then subjected to an electric current. The electric current causes the ore to break down into its constituent elements, with the metal ions being attracted to the cathode (negative electrode) where they gain electrons and are reduced to metal atoms.

For instance, in the extraction of aluminium from its ore (bauxite), the ore is first treated with sodium hydroxide to produce aluminium hydroxide. This is then heated to produce pure aluminium oxide, which is dissolved in molten cryolite to lower its melting point. When an electric current is passed through this mixture, aluminium ions are reduced at the cathode to form aluminium metal, while oxygen is formed at the anode.

Similarly, in the extraction of sodium from its ore (rock salt), the ore is dissolved in water and then electrolysed. Sodium ions are reduced at the cathode to form sodium metal, while chlorine gas is produced at the anode.

In summary, electrolysis is a crucial process in the extraction of metals from their ores. It allows for the extraction of highly reactive metals that cannot be reduced by carbon, and produces pure metal at the cathode.