Aluminium manufacture (AQA GCSE C2 7.3)

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Created by: Alan Donovan
Created on: 14-05-13 09:20

What sort of bonding does aluminium oxide, Al2O3, have?

Ionic - it's a metal and a non-metal joined together

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Why does aluminium oxide have a high melting point?

It has strong forces of attraction between the oppositely charged ions

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Why can't solid aluminium oxide conduct electricity?

The ions are in fixed positions - they can't move

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Why can molten aluminium oxide conduct electricity?

The ions are free to move

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What is the role of the cryolite?

It lowers the melting point - so reducing electrical energy costs

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What is formed at the negative electrode?

Molten aluminium

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What is the half equation for the reaction at the negative electrode?

Al3+ + 3e --> Al

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Is the reaction at the negative electrode reduction or oxidation?

Reduction (OILRIG - reduction is gain of electrons)

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What is the positive electrode made of?

Graphite (carbon)

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What is formed at the positive electrode?

Oxygen gas

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What is the half equation for the reaction at the positive electrode?

2O2- -4e --> O2 OR 2O2- --> O2 + 4e

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Is the reaction at the positive electrode reduction or oxidation?

Oxidation (OILRIG - oxidation is loss of electrons)

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Why do the positive electrodes have to be replaced frequently?

The carbon reacts with the oxygen to form CO2, so the electrode wears away

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Other cards in this set

Card 2

Front

Why does aluminium oxide have a high melting point?

Back

It has strong forces of attraction between the oppositely charged ions

Card 3

Front

Why can't solid aluminium oxide conduct electricity?

Back

Card 4

Front

Why can molten aluminium oxide conduct electricity?

Back

Card 5

Front

What is the role of the cryolite?

Back

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Aluminium manufacture (AQA GCSE C2 7.3)