EasyChemistryHigh School (9–10)GeneralChemical Reactions › Energy Changes and CorrosionConceptualBoard Exam
Say whether each change is exothermic or endothermic…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
Say whether each change is exothermic or endothermic.
- a matchstick burning
- an egg cooking in boiling water
- a cold pack: ammonium nitrate dissolving in water
- vegetables rotting in a compost pit
- brine being split by an electric current
- a sparkler burning
Need a reminder? The key ideaShow
An exothermic change gives out heat, so the surroundings warm up. An endothermic change takes heat in, so they cool. Heat taken by water: , with .
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. Exothermic. (a) the burning match, (d) the rotting vegetables and (f) the sparkler give out heat.
Step 2. Endothermic. (b) the egg cooks only while heat is supplied, (c) the cold pack takes in heat, and (e) electrolysis needs electrical energy.
Answer: exothermic: a, d, f. Endothermic: b, c, e.
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