New
New
Year 10
Edexcel
Higher

Energy changes in reactions

I can complete a series of practicals to measure the temperature change and record appropriate results, concluding whether the reactions were exothermic or endothermic.

New
New
Year 10
Edexcel
Higher

Energy changes in reactions

I can complete a series of practicals to measure the temperature change and record appropriate results, concluding whether the reactions were exothermic or endothermic.

Lesson details

Key learning points

  1. Changes in heat energy accompany salts dissolving in water.
  2. Changes in heat energy accompany neutralisation, displacement and precipitation reactions.
  3. Exothermic and endothermic reactions have everyday uses.
  4. When reactions take place in solution, temperature changes can be measured to reflect the energy changes.

Common misconception

Pupils struggle to identify the surroundings in exothermic and endothermic reactions and why the temperature decreases in endothermic reactions when energy is transferred into the reaction.

Explain that the surroundings are where you are making the temperature measurements and that the energy is transferred from the thermal energy store of the surroundings to the chemical energy store of the reaction.

Keywords

  • Exothermic - An exothermic chemical reaction is a type of reaction in which energy is transferred from the reactants to the surroundings e.g. combustion.

  • Endothermic - An endothermic chemical reaction is a type of reaction in which energy is transferred from the surroundings to the products e.g. photosynthesis.

  • Solution - A solution is formed when a substance dissolves into a liquid.

  • Calorimetry - Calorimetry is an experiment than can be used to measure an energy change during a reaction.

Get the pupils to experimentally identify different exothermic and endothermic reactions and then explain why they are seeing a temperature change, identifying the surroundings in each case.
Teacher tip

Equipment

Beakers, polystyrene coffee cups and lids, thermometers or temperature probes, stirring rods.

Licence

This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

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6 Questions

Q1.
Match the following state symbols to the correct meaning.
Correct Answer:(aq),aqueous

aqueous

Correct Answer:(s),solid

solid

Correct Answer:(l),liquid

liquid

Correct Answer:(g),gas

gas

Q2.
Which of the following statements about exothermic reactions are true?
Correct answer: They cause an increase in temperature.
They transfer energy from the surroundings to the products.
They cause a decrease in temperature.
Correct answer: They transfer energy from the reactants to the surroundings.
Q3.
What is the SI unit for energy?
Correct Answer: joule, Joule, joules, Joules
Q4.
Which statement about energy is correct?
It can be created and destroyed.
It can be created, but not destroyed.
It can be destroyed, but not created.
Correct answer: It cannot be created or destroyed.
Q5.
The hotter an object, the more energy is present in its store of energy.
Correct answer: thermal
elastic potential
kinetic
magnetic
Q6.
Which of the following methods of energy transfer involves only the vibration of particles?
thermal radiation
Correct answer: thermal conduction
thermal convection

6 Questions

Q1.
Match the following terms to the correct definition.
Correct Answer:Exothermic,Chemical reaction in which energy is transferred to the surroundings.

Chemical reaction in which energy is transferred to the surroundings.

Correct Answer:Endothermic,Chemical reaction in which energy is transferred to the products.

Chemical reaction in which energy is transferred to the products.

Correct Answer:Solution,Formed when a substance dissolves in a liquid.

Formed when a substance dissolves in a liquid.

Correct Answer:Calorimetry,An experiment used to measure energy change during a reaction.

An experiment used to measure energy change during a reaction.

Q2.
Which of the following are examples of exothermic chemical reactions?
Correct answer: Most neutralisation reactions
Correct answer: Respiration
Thermal decomposition
All precipitation reactions
Q3.
After an endothermic reaction, the temperature of the surroundings .
Increases
Correct answer: Decreases
Stays the same
Q4.
Which of the following are examples of everyday uses of exothermic reactions?
Self-cooling drinks
Correct answer: Self-heating drinks
Sports injury cool packs
Correct answer: Hand warmers
Q5.
Barium sulphate, BaSO₄, is a precipitate produced during a chemical reaction. Which state symbols should appear after BaSO₄ in the symbol equation?
Correct Answer: (s), s
Q6.
A student measured the initial temperature of a reaction as 22°C and the final temperature as 16°C. Which of these statements about the reaction are true?
Correct answer: The difference in temperature is -6°C.
Correct answer: The reaction is endothermic.
The reaction is exothermic.
The reaction could be combustion.