4.4.3.3 - Using electrolysis to extract metals

What is the main drawback of using electrolysis?

Large amounts of energy are used in the extraction process to melt the compounds and to produce the electrical current

As lots of energy is required this makes the method very expensive

When Is electrolysis used to extract a metal?

Electrolysis is used if the metal is too reactive to be extracted by reduction with carbon or if the metal reacts with carbon.

How is Aluminium manufactured (extracted) ?

Aluminium is manufactured by the electrolysis of a molten mixture of aluminium oxide and cryolite using carbon as the positive electrode (anode).

From what ore is Aluminium extracted from?

The ore Bauxite

Why is aluminium oxide mixed with cryolite?

To lower it’s melting point (making it less expensive)

Describe the process of extracting Aluminium.

1. Aluminium Is extracted from the ore bauxite by electrolysis - bauxite contains aluminium oxide

2. Aluminium oxide has a very high melting temperature - so its mixed with cryolite to lower the melting point

3. The molten mixture contains free ions - so it’s able to conduct electricity

4. The positive Al3+ ions are attracted to the cathode - when they each gain 3 electrons and turn into aluminium atoms (and then they sink to the bottom of the electrolysis sink)

5. The negative O2- ions are attracted to the anode - where they lose two electrons and combine to form O2 molecules

know equation pls

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