Electrolysis of Aluminium Oxide Concepts

The video explains the extraction of aluminium, the most abundant metal on Earth, which is costly due to high electricity usage. Aluminium is extracted from bauxite ore, which is purified to yield aluminium oxide. The extraction process involves electrolysis, where aluminium oxide is dissolved in molten cryolite to lower its melting point. The steel case acts as a cathode, and graphite anodes are used. Aluminium forms at the cathode and sinks, while oxygen forms at the anode, reacting with carbon to produce carbon dioxide, causing the anode to wear away. The video concludes with a summary of the process and its high cost due to electricity consumption.

Why is aluminium considered expensive to extract despite being abundant?

• It is difficult to transport.

• It requires a lot of electricity.

• It is not recyclable.

• It is rare and hard to find.

What is the name of the ore from which aluminium is extracted?

• Alumina

• Graphite

• Bauxite

• Cryolite

Why is cryolite used in the electrolysis of aluminium oxide?

• To reduce the melting point.

• To act as a catalyst.

• To provide a source of carbon.

• To increase the melting point.

What forms at the negative cathode during the electrolysis of aluminium oxide?

• Oxygen gas

• Graphite

• Carbon dioxide

• Aluminium metal

What happens to the oxygen ions at the positive anode?

• They are reduced.

• They form aluminium.

• They gain electrons.

• They are oxidized.

What is a consequence of the reaction at the positive anode?

• The anode produces aluminium.

• The anode becomes stronger.

• The anode wears away.

• The anode becomes a cathode.

What is the overall chemical reaction in the electrolysis of aluminium oxide?

• Aluminium to aluminium oxide and oxygen

• Carbon dioxide to carbon and oxygen

• Aluminium oxide to aluminium and oxygen

• Oxygen to aluminium and aluminium oxide

Why does the anode need to be replaced regularly?

• It becomes too heavy.

• It dissolves in cryolite.

• It reacts with oxygen to form carbon dioxide.

• It melts due to high temperature.

What is a key reason for the high cost of aluminium extraction?

• The need for rare catalysts.

• The large amount of electricity required.

• The high melting point of aluminium.

• The scarcity of bauxite.

What is the role of graphite in the electrolysis process?

• It increases the temperature.

• It forms the electrodes.

• It reduces the cost.

• It acts as a solvent.