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Question
Aluminium is a more active metal than iron, but suffers less corrosion. Why?
Solution
When aluminium is exposed to atmospheric air, it combines with oxygen, and a film of aluminium oxide (Al2O3) is formed at the surface. This hard, tightly adhering film prevents corrosion.
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RELATED QUESTIONS
Answer the following questions with respect to the electrolytic process in the extraction of aluminum:
Explain why powdered coke is sprinkled over the electrolytic mixture.
For graphite, explain its significance in the extraction of aluminium.
Explain the following:
In construction work, why is the alloy of aluminium-duralumin used rather than pure aluminium?
Give reason for the following:
Aluminium oxide cannot be reduced by carbon.
For the substance listed below, explain its role in the extraction of aluminium: Bauxite
For the substance listed below, explain its role in the extraction of aluminium: Sodium hydroxide
A to F below relate to the source and extraction of either zinc or aluminium.
- Bauxite
- Coke
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- Froth floatation
- Sodium hydroxide solution
- Zinc blende
Fill in the blanks using the most appropriate words from A to F:
(i) The ore from which aluminium is extracted must be treated with ______ so that pure aluminium oxide can be obtained.
(ii) Pure aluminium oxide is dissolved in ______ to make a conducting solution.
Explain why :
In the electrolysis of alumina using the Hall Heroult's Process the electrolyte is covered with powdered coke.
State the relevant reason for the following:
Graphite anodes are continuously replaced during the electrolysis of alumina.
The compound that is not a constituent of the electrolytic mixture used in Hall-Heroult's process is ______.
