Year 9 - Science
Practical: red cabbage indicator solution
Acids and bases
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This pupil-friendly study guide includes a unit summary, clear notes, common mistakes, and quick questions with answers.
Unit Summary
This unit covers acids, alkalis, and their neutralisation reactions, the pH scale, and the reactions of acids with metals and alkalis. It also examines the chemical properties of metal and non-metal oxides. Emphasis is on evaluating risks, using appropriate techniques, and making observations.
Lesson Summary
You will learn to make red cabbage indicator solution and use it to test solutions to find out if they are acid or alkali.
Key Notes
- Red cabbage solution is pink or red in an acid, purple in a neutral solution, and green in an alkali.
- Different chemical indicators have their advantages and disadvantages.
- Universal indicator will turn many different colours depending on pH.
Vocabulary To Learn
- universal indicator solution: a solution or paper that will turn different colours depending on pH of the solution.
- pH scale: is a scale from 1 to 14 used to measure the acidity or alkalinity of solutions. pH7 is for neutral solutions.
- pestle and mortar: are tools used to crush and grind substances. The pestle is a grinding club and the mortar a heavy bowl.
- chemical indicator: is a chemical that will change colour to indicate the presence of a substance, for example if a solution is an acid or alkali.
- solution: formed when a substance dissolves into a liquid.
Common Mistakes To Avoid
- Pupils often think that the red cabbage will change to the same colours as universal indicator solution.
3 Quick Questions (With Answers)
1. Explain the scientific idea in this lesson using two key points.
Red cabbage solution is pink or red in an acid, purple in a neutral solution, and green in an alkali. Different chemical indicators have their advantages and disadvantages.
2. Define this scientific word and use it in context. 'universal indicator solution'
a solution or paper that will turn different colours depending on pH of the solution. Include the word in a full scientific explanation, not as a single label.
3. Correct this common scientific misunderstanding.
Mistake: Pupils often think that the red cabbage will change to the same colours as universal indicator solution. Correction: Remind pupils that there are many different indicators used to show different pH.
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