What are chemical reactions used for? | 11-14 years

Students work with a series of cards (showing word descriptions, photographs or equations) related to chemical reactions that are used as energy sources or for making new materials or that are important in biological systems. The cards help students to think about and discuss these uses.

Learning objectives

Students will be able to:

• Describe the uses of chemical reactions in everyday situations.

Sequence of activities

Introduction

1. Display:
   1. A battery driven fan, children’s toy or similar device.
   2. A long nail dipped in copper(II) sulfate solution so that it becomes coated with copper.
   3. A geranium or similar growing plant.
2. Ask what links the three items (they are all examples of important chemical reactions). Reveal the learning objective.
3. Explain that they are going to use the ideas that they have met before to group information about different chemical reactions into three different categories.

Stage 1

1. Arrange students into groups of three.
2. Describe the process that you want them to follow. They are to sort cards that show a word description, a photograph, a word equation or a symbol equation related to a chemical reaction, using the following headings:
   • Chemical reactions can be used as energy sources.
   • Chemical reactions are used to make new materials.
   • Chemical reactions are important in biological systems.

Stage 2

Give each group a set of ‘What are chemical reactions used for?’ cards (three headings plus 12 ‘uses’ cards). Circulate and support the groups while:

1. They set out the headings for the three reaction categories on a table.
2. One member shuffles the 12 cards and then deals four cards to each member of the group.
3. In turn, each student places one of their cards under one of the headings, explaining why they are placing it there and whether or not it also fits under a different heading.
4. The other group members agree with the position of the card or suggest an alternative.
5. They place all 12 cards under the appropriate headings.

When every group has finished, allow groups to look at the card placings devised by other students and to compare these with their own.

Plenary

Organise a plenary. Give a copy of the ‘Summary sheet’ to each student. Ask:

1. One group to describe which categories they allocated.
2. Other groups if they allocated the information in a different way.
3. Individuals to complete the ‘Summary sheet’.

Feedback

Take in the ’Summary sheets’ and comment on any features that the student still needs to develop.

Commentary

Showing artefacts and using probing questions is a good way of introducing the learning objective.

Working in small groups encourages students to talk about and consolidate what they understand. They have to explain and evaluate their own and their peers’ ideas and so strengthen their learning.

The plenary and the summary sheet are essential to confirm learning.

Answers

Chemical reactions that can be used as energy sources include:

• Burning methane.
• Burning octane.
• Magnesium reacting with copper sulfate.
• The conversion of glucose into carbon dioxide and water.

Chemical reactions that are used to make new materials include:

• Water and carbon dioxide reacting to form glucose and oxygen.
• The conversion of glucose into carbon dioxide and water.
• The reaction of polyisocyanate and polyol to form polyurethane.
• The reaction between magnesium and copper sulfate.
• The reaction of haemoglobin and oxygen to form oxyhaemoglobin.
• The conversion of ethene into polyethene.
• The reaction of 1,2-diaminohexane and hexanedioic acid to form nylon-6,6.
• The burning of methane to form carbon dioxide and water.
• The burning of octane to form carbon dioxide and water.
• The conversion of iron ore to iron.

Chemical reactions that are important in biological systems include:

• Water and carbon dioxide reacting to form glucose and oxygen.
• The conversion of glucose into carbon dioxide and water.
• The reaction of haemoglobin and oxygen to form oxyhaemoglobin.