Introduction to reversible chemical reactions
Lesson details
Learning outcome
I can describe reversible chemical reactions, represent them using chemical equations, and give examples.
Key learning points
- Different types of arrows (→, ⇌) are used in chemical equations to indicate the nature of the reaction.
- Reversible reactions are symbolised using the double-headed arrow (⇌) in chemical equations.
- In a reversible reaction, both the forward and reverse reactions can occur under the right conditions.
- hydrated copper sulfate (blue) ⇌ anhydrous copper sulfate (white) + water
- ammonium chloride ⇌ ammonia + hydrogen chloride
Keywords
Reversible reaction - A chemical reaction where the reactants form products that, in turn, react together to reform the reactants.
Hydrated (salt) - A salt that contains water molecules within its crystal structure, shown by a dot in its formula, e.g. hydrated copper(II) sulfate (CuSO₄·5H₂O).
Anhydrous (salt) - A salt that does not contain any water molecules in the crystal structure, e.g. anhydrous copper(II) sulfate (CuSO₄).
Double-headed arrow (⇌) - Used to show that a chemical reaction is reversible.
Single-headed arrow (→) - Used to show the direction of an (irreversible) chemical reaction, showing that reactants form products.
Common misconception
Pupils often think that a reversible reaction will always go to completion in one direction before reversing.
Explain that in a reversible reaction, if the conditions allow it, both the forward and backward reaction can occur at the same time.
Teacher tip
Use simple experiments to show that reversibility does not mean full completion in one direction before the reverse begins.
Equipment
Test tubes, clamp and stand, ammonium chloride, hydrated copper(II) sulfate, Bunsen burners, mineral wool, delivery tube and bung, ice bath.
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 key words to their definition.
energy is transferred from the surroundings to the reaction
energy is transferred from the reaction to the surroundings
Q2.Which of the following statements about chemical reactions are correct?
Q3.The rate of a chemical reaction is equal to the amount of product formed per unit .
Q4.A chemical reaction produces 0.5 g of gas in 10 seconds.
Which is the correct rate of reaction?
Q5.The rate of a reaction can be changed by varying concentration or temperature, but also by changing the of a solid reactant.
Q6.Which of the following statements about catalysts is incorrect?
Assessment exit quiz
6 Questions
Q1.Match the following key terms to their definition.
reactants form products, and the reaction goes to completion
both forward and backward reactions occur under the correct conditions
Q2.Which of the following symbols is used to indicate a reversible reaction?
Q3.In reversible reactions, the forward and backward reactions have different energy changes.
When energy is taken in from the surroundings, the reaction is called an reaction.
Q4.True or false? In a reversible reaction, the forward reaction needs to reach completion before the backward reaction can start.
Q5.The direction of reversible reactions can be influenced by changing conditions, such as temperature. By cooling a reaction down, the system will change to favour the reaction.
Q6.Match the following key words to their definition.
contains water molecules in its crystal structure (dot in the formula)
does not contain any water molecules in the crystal structure
To help you plan your 11 chemistry lesson on: Introduction to reversible chemical reactions, download all teaching resources for free and adapt to suit your pupils' needs...
To help you plan your 11 chemistry lesson on: Introduction to reversible chemical reactions, download all teaching resources for free and adapt to suit your pupils' needs.
The starter quiz will activate and check your pupils' prior knowledge, with versions available both with and without answers in PDF format.
We use learning cycles to break down learning into key concepts or ideas linked to the learning outcome. Each learning cycle features explanations with checks for understanding and practice tasks with feedback. All of this is found in our slide decks, ready for you to download and edit. The practice tasks are also available as printable worksheets and some lessons have additional materials with extra material you might need for teaching the lesson.
The assessment exit quiz will test your pupils' understanding of the key learning points.
Our video is a tool for planning, showing how other teachers might teach the lesson, offering helpful tips, modelled explanations and inspiration for your own delivery in the classroom. Plus, you can set it as homework or revision for pupils and keep their learning on track by sharing an online pupil version of this lesson.
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