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 process uses graphite electrodes, with aluminium forming at the cathode and oxygen reacting at the anode to form carbon dioxide. The anode wears away and needs regular replacement, adding to the cost.

What makes aluminium a valuable material for manufacturing aeroplanes and drink cans?

• It is cheaper to extract than other metals.

• It is the most abundant metal on Earth.

• It has a high density and corrodes easily.

• It conducts heat and electricity well, has a low density, and does not corrode.

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

• Graphite

• Bauxite

• Alumina

• Cryolite

Why is cryolite used in the electrolysis of aluminium oxide?

• It lowers the melting point of aluminium oxide, reducing costs.

• It is cheaper than aluminium oxide.

• It acts as a catalyst in the reaction.

• It increases the melting point of aluminium oxide.

Which compound is used to dissolve aluminium oxide to make it molten?

• Graphite

• Carbon dioxide

• Cryolite

• Bauxite

What is the role of graphite in the electrolysis of aluminium oxide?

• It forms the negative cathode and positive anode.

• It reacts with aluminium to form aluminium oxide.

• It increases the melting point of cryolite.

• It acts as a catalyst.

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

• Graphite

• Carbon dioxide

• Oxygen gas

• Pure aluminium metal

What happens to the oxygen ions at the positive anode during electrolysis?

• They gain electrons and form oxygen gas.

• They lose electrons and form carbon dioxide.

• They remain unchanged.

• They combine with aluminium ions to form aluminium oxide.

What is the overall chemical reaction occurring during the electrolysis of aluminium oxide?

• Aluminium oxide is oxidized to form aluminium and carbon dioxide.

• Aluminium oxide decomposes into aluminium and graphite.

• Aluminium oxide is reduced to aluminium and oxygen.

• Aluminium oxide reacts with cryolite to form aluminium.

Why does the positive anode need to be replaced regularly in the electrolysis process?

• It melts due to high temperatures.

• It reacts with oxygen to form carbon dioxide, wearing away the anode.

• It is consumed in the formation of aluminium.

• It corrodes due to the presence of water.

What is one of the main reasons for the high cost of aluminium extraction?

• The abundance of aluminium on Earth.

• The high electricity consumption required for electrolysis.

• The low melting point of aluminium oxide.

• The low density of aluminium.