Distinguish between exothermic and endothermic reactions with examples. Describe an activity to show both.
How to lay out the answer. Follow the frame, then write it in your own words.
1 · Define exothermic. A reaction that releases heat to the surroundings: CaO + H₂O → Ca(OH)₂ + heat.
2 · Define endothermic. A reaction that absorbs heat from the surroundings: CaCO₃ + heat → CaO + CO₂.
3 · More examples.
Exothermic: burning of methane, respiration, neutralisation
Endothermic: photosynthesis, N₂ + O₂ → 2NO
4 · Draw the activity. [Two test tubes with thermometers: A with quicklime in water (temperature rises), B with ammonium chloride in water (temperature falls), both labelled]
5 · Real-life link. Respiration keeps the body warm; cold packs for sprains use a process that absorbs heat.
6 · Close in one line. Thus exothermic reactions release heat and endothermic reactions absorb it.
Scoring tip: Write '+ heat' on the correct side of each equation. That one detail shows you know the difference.
