Science 8 · Unit 8: Chemical reactions · Cambridge Lower Secondary Science Stage 8

8.2 Endothermic reactions

20 questions · e.g. Why use insulated cups to investigate temperature changes?

Practice

Questions

1. What happens to the temperature in an endothermic reaction?
- It increases.
- It decreases.
- It boils.
- It stays the same.
Check
2. A reaction starts at 21 °C and ends at 45 °C. Exothermic or endothermic?
- exothermic
- endothermic
Check
3. A reaction starts at 19 °C and ends at 16 °C. Exothermic or endothermic?
- exothermic
- endothermic
Check
4. Sherbet sweets give a cool, fizzy feeling. What kind of reaction is it?
- exothermic
- endothermic
Check
5. Magnesium in hydrochloric acid makes the test tube warm. What kind of reaction is it?
- exothermic
- endothermic
Check
6. Why use insulated cups to investigate temperature changes?
- to change the colour
- they are cheaper than glass
- to make reactions faster
- to reduce energy transfer to or from the surroundings
Check
7. Give an example of a useful product using an exothermic reaction.
- a hand warmer
- a refrigerator
- ice cream
- an instant cold pack
Check
8. Give an example of a useful product using an endothermic reaction.
- a gas cooker
- an instant cold pack for sports injuries
- a firework
- a hand warmer
Check
9. What is the difference between an endothermic reaction and an endothermic process?
- A process always makes new substances.
- Reactions never change temperature.
- A reaction makes new substances; a process like melting does not.
- They are the same.
Check
10. Which is an endothermic process (not a reaction)?
- evaporation of water
- rusting iron
- burning wood
- magnesium in acid
Check
11. Why does a wet cloth over bottles keep them cool?
- Water is always cold.
- The cloth makes cold air.
- The cloth reflects heat.
- Water evaporating takes energy from the bottles.
Check
12. In particle terms, why does evaporation cool things?
- Particles become colder by themselves.
- New cold particles are made.
- The most energetic particles escape, leaving slower ones behind.
- Particles stop moving.
Check
13. A reaction goes from 18 °C to 22 °C. What is the temperature change?
- 0 °C
- +4 °C (exothermic)
- 40 °C
- −4 °C (endothermic)
Check
14. Is photosynthesis exothermic or endothermic?
- exothermic
- endothermic
Check
15. Is melting ice exothermic or endothermic?
- exothermic
- endothermic
Check
16. All of an archer's arrows land close together, but far from the centre. How would you describe the shots?
- accurate but not precise
- neither accurate nor precise
- accurate and precise
- precise but not accurate
Check
17. Potassium chloride is stirred into water and the beaker gets cold. What is this?
- an endothermic process
- an exothermic process
- an endothermic reaction
- an exothermic reaction
Check
18. Why does eating sherbet give a fizzy feeling in your mouth?
- The sugar melts.
- The sherbet is very hot.
- Saliva turns into gas.
- The reaction makes carbon dioxide gas.
Check
19. A self-heating can mixes calcium oxide with water. What kind of reaction warms the food?
- no reaction
- endothermic
- dissolving only
- exothermic
Check
20. Is water freezing endothermic or exothermic?
- endothermic
- exothermic
Check