Chemistry
(a) Aluminium is a more active metal than iron but suffers less corrosion. Why?
(b) Explain and give reasons why aluminium vessels should not be cleaned with powders containing alkalis.
Metallurgy
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Answer
(a) Aluminum forms a thin, protective layer of aluminium oxide (Al2O3) on its surface that prevents further oxidation and corrosion. The oxide layer acts as a barrier that protects the metal underneath from being exposed to the elements, thus minimizing corrosion.
(b) Aluminium vessels should not be cleaned with powders containing alkalis because alkalis are water soluble and aluminum metal will react with alkalis to form sodium meta aluminate that can be toxic to our health.
2Al + 2NaOH + 2H2O ⟶ 2NaAlO2 + 3H2
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