WAEC Chemistry 2021 Theory — Question 26
Question 26 of 31 from the West African Examinations Council (WAEC) Chemistry 2021 Theory paper, with the correct answer and a full explanation.
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5(a). With the aid of an equation, explain briefly why aluminium metal is not affected by air.
Model answer
Aluminium reacts with oxygen in the air to form a thin, non-porous, insoluble protective layer of aluminium oxide on its surface: 4Al(s) + 3O2(g) → 2Al2O3(s). This oxide film adheres tightly and protects the metal underneath from further attack/corrosion by air or moisture.
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