Starter quiz
- What is the role of a catalyst in a chemical reaction?
- It has no effect on the activation energy.
- It increases the activation energy required for the reaction to start.
- It lowers the activation energy required for the reaction to start. ✓
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- What happens during an exothermic reaction?
- Energy is transferred from the reactants to the surroundings. ✓
- Energy is transferred from the surroundings to the reactants.
- No energy transfer occurs.
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- What happens during an endothermic reaction?
- Energy is transferred from the reactants to the surroundings.
- Energy is transferred from the surroundings to the reactants. ✓
- No energy transfer occurs.
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- ______ is needed for a chemical reaction to start.
- 'activation energy' ✓
- What is energy transfer in a chemical reaction?
- the creation of energy in a reaction
- the disappearance of energy during a reaction
- the movement of energy from one store to another ✓
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- What is the role of activation energy in a chemical reaction?
- the energy absorbed during the reaction
- the energy released during the reaction
- the minimum energy needed for the reaction to start ✓
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Exit quiz
- What does a reaction profile show?
- energy changes during a chemical reaction ✓
- pressure changes during a reaction
- temperature changes during a reaction
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- Which of the following reaction profiles shows an endothermic reaction?
energy profile A
energy profile B
energy profile C ✓
- Which of the following reaction profiles correctly represents the activation energy of the reaction with a red arrow, and where R is the reactant and P is the product?
energy profile A
energy profile B
energy profile C
energy profile D ✓
- How can you identify an exothermic reaction from its reaction profile?
- The energy of the products is higher than the reactants.
- The energy of the products is lower than the reactants. ✓
- There is no change in energy.
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- How does the activation energy of a reaction influence its rate?
- Activation energy does not affect the reaction rate.
- Higher activation energy means a faster reaction rate.
- Higher activation energy means a slower reaction rate. ✓
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- Why might a reaction with a low activation energy be preferred in industrial processes?
- It can occur at lower temperatures, saving energy costs. ✓
- It produces more products.
- It requires more reactants.
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Worksheet
Presentation
Video
Lesson Details
Key learning points
- A reaction profile compares the amount of energy the products of a reaction have compared to the reactants.
- Exothermic chemical reactions transfer energy from reactants to the surroundings causing an increase in temperature.
- Endothermic chemical reactions transfer energy from the surroundings to the products causing a decrease in temperature.
- Activation energy is the minimum amount of energy transferred to reactants that allows a chemical reaction to start.
Common misconception
Pupils often confuse energy with temperature and therefore expect the products to be higher than the reactants for exothermic reactions i.e. due to temperature increase, and lower for endothermic.
It is useful to discuss the energy transfers occurring during the reaction e.g. exothermic reactions involve the reactant's chemical energy store converting to a smaller chemical energy store in the products and a thermal energy store.
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.
Activation energy - The minimum energy that the particles must have in order to react is known as the activation energy.
Reaction profile - A reaction profile is a diagram showing the energy changes during exothermic and endothermic reactions.