Extraction of aluminium

Question 1

what is the name of the ore used to extract aluminium

Answer 1

bauxite

Question 2

how is aluminium extracted

Answer 2

electrolytically

Question 3

what materials are the electrodes made of

Answer 3

graphite

Question 4

describe the process of aluminium extraction

Answer 4

-the bauxite is purified to aluminium oxide
Al₂O₃
-the Al₂O₃ has a high melting point so it is dissolved in molten cryolite producing an electrolyte with a low melting point
-a temperature of about 1000℃ is used and the molten solution is added to the cell which operates at about 5-6V (volts); the heat generated by the huge current keeps the electrolyte molten
-a lot of electricity is required for this process and it is a major expense

Question 5

describe reaction at the cathode

-ve electrode

Answer 5

the aluminium melts and colects at the bottom of the cell

Al³ + 3e‾ → Al

Question 6

describe reaction at the anode

+ve electrode

Answer 6

oxygen gas is formed
2O²‾ → O₂ + 4e‾
some of the oxygen produced reactions with the graphite to produce carbon dioxide
C + O₂ → CO₂
carbon electrodes burn away and need to be replaced regularly