Industrial Electrolytic Processes

YR11 Chemistry

Aluminium Extraction

Aluminium is obtained by the electrolytic reduction of its molten oxide, alumina (Al2O3). Because alumina has a very high melting point (2045 ºC), the mineral cryolite (Na3AlF6) is added to lower the melting point in order that the electrolysis may be carried out at about 950 ºC. The electrolytic cell has carbon anodes and a carbon cathode (which forms the lining of the tank in which the electrolysis takes place). Carbon dioxide is formed at the anodes, and aluminium at the cathode. It is heavier than the molten alumina/cryolite mixture, and sinks to the bottom of the cell, where it is tapped off. The procedure is known as the Hall-Heroult process.

Aluminium extraction is very demanding on electrical current (typically, 800 V and 70 000 A), and is economical only where power is cheap.

Silver Plated Cutlery

Electroplating consists of depositing a thin layer of a metal on another, either for protection or for the sake of appearance. Typically, a brass or nickel object is coated with a layer of silver by making use of electrolysis of a silver solution, using the object to be coated as the cathode:

The anode consists of pure silver, and the cathode is the object to be plated. The electrolyte is a mixture of silver nitrate with potassium cyanide.

The reactions are:

At the anode: Ag Ag+ + e-

At the cathode: Ag+ + e- Ag

The cyanide ensures a low concentration of silver ions, a condition for providing the best plating

Electrolysis has improved the quality of life in western society. Without Electrolysis many things that we as a society take for granted would not exists. The simplest thing as a phone would not work without copper wiring. Computers’ cars and most other forms of modern technology would not exist without the basic materials that are obtained from electrolysis.

o Transportation is a fast growing necessity for the modern country and its growing metropolises. Without it a country would not be able to continue living profitably. My education would be inaccessible
o Communication is essential in this day and age and is taken for granted I would be unable to communicate with friend and family who live great distances away from me.
o Technology such as computers would limit my information and my ability to school assignments and substantially reduce my out put.