MEDIUM
Lower Secondary Stage 9
IMPORTANT
Earn 100

When the fuels are burnt in oxygen, it is called combustion. Copy and complete this word equation for the combustion of a hydrocarbon:

Hydrocarbon + Oxygen → _____ + _____

Important Questions on Energy Transfers in Chemistry

EASY
Lower Secondary Stage 9
IMPORTANT
Cambridge Lower Secondary Science Stage 9: Student's Book>Chapter 8 - Energy Transfers in Chemistry>End of Chapter Review>Q 6
When the fuels are burnt in oxygen, it is called combustion. Combustion reaction transfer energy to the surroundings as heat. Is this an endothermic or exothermic reaction?
MEDIUM
Lower Secondary Stage 9
IMPORTANT
Cambridge Lower Secondary Science Stage 9: Student's Book>Chapter 8 - Energy Transfers in Chemistry>End of Chapter Review>Q 7

Which of these processes are endothermic?

a. Ice melting     b. Firework exploding     c. Steam condensing     d. Burning gas on a stove     e. Photosynthesis     f. Evaporation of water

HARD
Lower Secondary Stage 9
IMPORTANT
Cambridge Lower Secondary Science Stage 9: Student's Book>Chapter 8 - Energy Transfers in Chemistry>End of Chapter Review>Q 8
When you exercise, your body sweats to cool you down. Explain how this works.
EASY
Lower Secondary Stage 9
IMPORTANT
Cambridge Lower Secondary Science Stage 9: Student's Book>Chapter 8 - Energy Transfers in Chemistry>End of Chapter Review>Q 9

Instant cold packs can be made using ammonium nitrate and water. The pack contains a small bag of solid ammonium nitrate. This bag is inside another bag, which is full of water. When you squeeze the outer bag the smaller bag bursts. The ammonium nitrate dissolves in water and the pack becomes cold. 

Is this an endothermic process or exothermic process?

HARD
Lower Secondary Stage 9
IMPORTANT
Cambridge Lower Secondary Science Stage 9: Student's Book>Chapter 8 - Energy Transfers in Chemistry>End of Chapter Review>Q 9

Instant cold packs can be made using ammonium nitrate and water. The pack contains a small bag of solid ammonium nitrate. This bag is inside another bag, which is full of water. When you squeeze the outer bag the smaller bag bursts. The ammonium nitrate dissolves in water and the pack becomes cold.

Describe how energy is transferred between the reaction mixture and its surroundings. 

MEDIUM
Lower Secondary Stage 9
IMPORTANT
Cambridge Lower Secondary Science Stage 9: Student's Book>Chapter 8 - Energy Transfers in Chemistry>End of Chapter Review>Q 9

Instant cold packs can be made using ammonium nitrate and water. The pack contains a small bag of solid ammonium nitrate. This bag is inside another bag, which is full of water. When you squeeze the outer bag the smaller bag bursts. The ammonium nitrate dissolves in water and the pack becomes cold.

Explain how you know this.

MEDIUM
Lower Secondary Stage 9
IMPORTANT
Cambridge Lower Secondary Science Stage 9: Student's Book>Chapter 8 - Energy Transfers in Chemistry>End of Chapter Review>Q 10

A student planned an experiment to find out which substance would produce the biggest temperature decrease when added to either water or an acid. The chemicals she had access to were:

  • ammonium nitrate solid
  • sodium hydroxide solution
  • citric acid solution
  • sodium hydrogen carbonate solution
  • water 
  • dilute hydrochloric acid

State one problem the student would have in making this fair test.

MEDIUM
Lower Secondary Stage 9
IMPORTANT
Cambridge Lower Secondary Science Stage 9: Student's Book>Chapter 8 - Energy Transfers in Chemistry>End of Chapter Review>Q 10

A student planned an experiment to find out which substance would produce the biggest temperature decrease when added to either water or an acid. The chemicals she had access to were:

  • ammonium nitrate solid
  • sodium hydroxide solution
  • citric acid solution
  • sodium hydrogen carbonate solution
  • water 
  • dilute hydrochloric acid

How would you improve this method.