The electrolyte used during the electrolytic extraction of aluminium is Aluminium chloride solution.

Aluminium is a highly reactive metal and is not found in its pure form in nature. It is usually found in the form of its oxide, known as alumina (Al2O3). The extraction of aluminium from alumina involves a process called electrolysis, which requires the use of an electrolyte.

Electrolysis Process:
During the electrolysis of alumina, a mixture of alumina and cryolite (Na3AlF6) is used as the electrolyte. Cryolite is added to lower the melting point of alumina, making the electrolytic process more efficient. The mixture is heated to around 950-1000°C to facilitate the flow of ions.

Role of Aluminium Chloride:
Aluminium chloride (AlCl3) is added to the mixture as a flux. It helps to increase the conductivity of the electrolyte and lower its resistance, allowing the flow of electric current more easily. This is essential for the successful extraction of aluminium.

Function of the Electrolyte:
The electrolyte serves as a medium for the movement of ions during electrolysis. When an electric current is passed through the electrolyte, the alumina (Al2O3) dissociates into aluminium ions (Al3+) and oxygen ions (O2-). The aluminium ions migrate towards the cathode (negative electrode), where they gain electrons and are reduced to form aluminium metal. The oxygen ions migrate towards the anode (positive electrode), where they lose electrons and are oxidized to form oxygen gas.

Advantages of Aluminium Chloride:
- Aluminium chloride is a stable compound that can withstand the high temperatures required for the electrolytic extraction process.
- It has a high solubility in the electrolyte, ensuring a sufficient supply of positive aluminium ions for the reduction reaction at the cathode.
- The addition of aluminium chloride helps to increase the conductivity of the electrolyte, allowing for a more efficient flow of electric current.

In conclusion, aluminium chloride is used as a flux in the electrolytic extraction of aluminium to enhance the conductivity of the electrolyte and facilitate the successful extraction of aluminium metal from alumina.