Exothermic and endothermic chemical reactions
I can identify whether a chemical reaction is exothermic or endothermic and explain how I know.
Exothermic and endothermic chemical reactions
I can identify whether a chemical reaction is exothermic or endothermic and explain how I know.
Lesson details
Key learning points
- An exothermic chemical reaction causes an increase in temperature (of the surroundings).
- An endothermic chemical reaction causes a decrease in temperature (of the surroundings).
- An exothermic reaction transfers energy from the reactants to the surroundings.
- An endothermic reaction transfers energy from the surroundings to the products.
Keywords
Exothermic chemical reaction - is a type of reaction in which energy is transferred from the reactants to the surroundings, e.g. combustion.
Endothermic chemical reaction - is a type of reaction in which energy from the surroundings is transferred to the products, e.g. photosynthesis.
Dissipate - Thermal energy can dissipate which means it can be transferred to the environment and wasted.
Common misconception
The difference between the surroundings (where the reaction takes place, e.g. solution) and the environment (where the reaction mixture is, e.g. classroom). The existence of cold.
Use the separate terms of surroundings and environment throughout the lesson. Explain that thermal energy transfer only takes place from somewhere that is warmer and somewhere that is cooler.
Equipment
Content guidance
- Risk assessment required - equipment
Supervision
Adult supervision required
Licence
Lesson video
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Prior knowledge starter quiz
6 Questions
Q1.Match the following terms to their definitions.
substance present at the start of a chemical reaction
substance made during a chemical reaction
when chemical bonds are broken and new substances are formed
a reversible process that does not involve breaking chemical bonds
Q2.True or false? A change of state indicates that a chemical reaction has taken place.
Q3.Which of the following are examples of chemical reactions?
Q4.Hydrogen gas and magnesium chloride are formed when magnesium reacts with hydrochloric acid.
Which of the following represents the chemical equation for the reaction?
Q5.Burning is an example of ...
Select two correct answers.
Q6.Calculate the mass of carbon dioxide formed when 13.5 g of calcium carbonate reacts to form 7.6 g of calcium oxide.
calcium carbonate → calcium oxide + carbon dioxide
Assessment exit quiz
6 Questions
Q1.Match the following terms to their definitions.
energy is transferred from the reactants to the surroundings
energy from the surroundings is transferred to the products
energy is transferred (and lost) as 'heat' to the environment