Consider the following reaction : Fe₂O₃(s) + 2Al(s) → 2Fe(s) + Al₂O₃(s) Which of the following statements about the given reaction is NOT correct ?
- A.It is an example of displacement reaction
- B.It is highly endothermic reaction
- C.Fe₂O₃ acts as oxidizing agent
- D.This reaction is applicable to joining of railway tracks
Correct answer
Explanation
The correct answer is B, It is highly endothermic reaction. This is the thermite reaction, which is highly exothermic: it gives out so much heat that the iron formed comes out molten.
Aluminium is more reactive than iron, so it takes the oxygen from iron(III) oxide and displaces the iron. Aluminium is oxidised to aluminium oxide and iron oxide is reduced to iron, so it is also a redox reaction. The molten iron is run into the gap between two rails, which is why the method is called thermite welding; it is used to join railway tracks and to repair cracked machine parts.
A is not the answer: aluminium displacing iron from its oxide is a displacement reaction.
C is not the answer: Fe₂O₃ gives its oxygen to aluminium, so it is the oxidising agent and aluminium the reducing agent.
D is not the answer: joining railway tracks is the best-known use of this reaction.
Exam tip: thermite = Fe₂O₃ + Al, strongly exothermic, used to weld rails.
Practice Questions
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