Question

Extraction of aluminium

Answer 1

Aluminium ore is called bauxite. The bauxite is purified to yield a white powder, aluminium oxide, from which aluminium can be extracted. The extraction is done by electrolysis. But first the aluminium oxide must be made molten so that electricity can pass through it.

Answer 2

by hall heroult method we can extract aluminium from its ore

Hall-Heroult process is widely used in the extraction of aluminium. In Hall-Heroults process, pure Al2O3 is mixed with CaF2 or Na3AlF6. This results in lowering of the melting point of the mixture and increases its ability to conduct electricity.  A steel vessel with  lining of carbon and graphite rods is used. The carbon lining acts as cathode and graphite acts as anode. When electricity is passed through the electrolytic cell which consists of carbon electrodes oxygen is formed at the anode. This oxygen formed reacts with the carbon of the anode to form carbon monoxide and carbon dioxide. In this method of production of aluminium for every 1 kg of Al produced, approximately 0.5 Kg of carbon anode is burnt. The overall reaction is:

2Al2O3 + 3C → 4Al + 3CO2

The electrolytic reactions are:

At the cathode:

Al 3+ + 3e– → Al (l)

At the anode:

C (s) + O2- → CO (g) + 2e–

C (s) + 2O2- → CO2 (g) + 4e–

Aluminium is used in a wide range of applications in the field of transport, construction etc. Aluminium foils are used in the food industries for wrapping of food. The dust of this metal is used in paints. It is used in the extraction of manganese and chromiumfrom its oxides. As it is a soft metal and it can be moulded into any shape it is used in the manufacturing of storage cans.

hope it will help you........