Science at key stage 3 (Year 7)
Unit 7E: Acids and alkalis
Section 6: b. What happens when an acid is added to an alkali?
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Objectives |
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- that when an acid is added to an alkali, it lowers the pH
- that a neutral solution can be obtained by adding an acid to an alkali
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Activities |
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Outcomes |
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Children: |
- Ask pupils to explore what happens to the pH when a solution of an acid is added drop by drop to a solution of an alkali. Challenge pupils to predict what will happen if more acid is added, or if alkali is added to an acid, and test their predictions using a pH monitor and datalogger.
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- describe that when an acid is added to an alkali, the pH of the mixture falls and vice versa
- explain how to obtain a neutral solution
- find information in reference books, on CD-ROMs, or from databases
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Points to note |
- ICT: pH logging using ICT could be used to record changes and generate a graph.
- Teachers may wish to emphasise that acidity and alkalinity are measured on a continuous scale.
- Extension: pupils could be asked to describe what computer-generated graphs show about the way pH changes as more alkali is added.
- Extension: pupils could be asked to investigate changes in temperature during neutralisation and be introduced to the idea that a chemical reaction is taking place.
Safety
- 0.4 mol dm-3 solutions of acid and alkali can be used. These may be irritant, so eye protection is needed
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This unit is divided into sections. Each section contains a sequence of
activities with related objectives and outcomes. You can view this unit by
moving through the sections or print/download the whole unit.
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