Decomposition reactions can be driven by different forms of energy. Name the forms of energy that can cause decomposition reactions and give one example of a decomposition reaction for any one of them.
Generated by claude-sonnet-4-6 · 2026-06-26 00:53 · grounding rag
Model Answer
Decomposition reactions can be driven by three forms of energy:
- Heat (Thermal decomposition)
- Light (Photolytic decomposition)
- Electricity (Electrolytic decomposition)
Example (Heat):
$$2\text{FeSO}_4(s) \xrightarrow{\Delta} \text{Fe}_2\text{O}_3(s) + \text{SO}_2(g) + \text{SO}_3(g)$$
Ferrous sulphate decomposes on heating to give ferric oxide, sulphur dioxide and sulphur trioxide.
Source: Chapter 1 – Chemical Reactions and Equations
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Explanation
- The question has two parts: name the energy forms (1 mark each, total 2 marks) and give one example (1 mark). Name all three forms clearly.
- Any valid equation for heat, light, or electricity is acceptable. Common choices: heat → FeSO₄ or CaCO₃; light → AgCl or AgBr; electricity → H₂O electrolysis.
- Write the equation with state symbols and the energy symbol (Δ or hν) above the arrow for full marks.
- Examiners award 1 mark for each correctly named energy form and 1 mark for a correct balanced equation with appropriate energy indicated.