Science (086) — AI-generated practice question

The thermit reaction is a displacement reaction between aluminium and iron(III) oxide:

$$\text{Fe}_2\text{O}_3 + 2\text{Al} \rightarrow \text{Al}_2\text{O}_3 + 2\text{Fe}$$

This reaction is highly exothermic — it releases a very large amount of heat (approximately 3000°C). The melting point of iron is about 1535°C, which is far lower than the heat produced. Therefore, the iron formed immediately melts and is obtained in the molten state, which flows into the gap between railway tracks and solidifies to join them firmly.

Source: Chapter 1 (Displacement Reactions); Chapter 3, Section 3.2.4

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• 1 mark: Correct balanced chemical equation.
• 1 mark: Stating the reaction is highly exothermic / releases enormous heat.
• 1 mark: Explaining that heat produced exceeds iron's melting point, so iron is obtained in molten form.

Examiners look for the equation written correctly (Fe₂O₃ + 2Al → Al₂O₃ + 2Fe) and a logical two-step explanation linking exothermic heat → temperature exceeds melting point of iron → molten iron. Don't just say "it's exothermic" — you must connect it to why iron melts.