Practical: red cabbage indicator solution
Lesson details
Learning outcome
I can make red cabbage indicator solution and use it to test solutions to find out if they are acid or alkali.
Key learning 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.
- Universal indicator will turn many different colours depending on pH.
Keywords
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 misconception
Pupils often think that the red cabbage will change to the same colours as universal indicator solution.
Remind pupils that there are many different indicators used to show different pH.
Teacher tip
Make sure pupils only cover the cabbage with a suitable volume of water to produce a concentrated red cabbage indicator solution. Other flowers, fruit and vegetables can also be used. Butterfly Pea Flower is a good alternative/addition and is readily available to purchase online.
Equipment
Red cabbage, kettle, pestle and mortar, beaker, pipette, filter paper, funnel, conical flask, stirring rod, spotting tile, universal indicator, red and blue litmus, solutions with varying pH's.
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 keywords to the correct description.
Q2.Which of the following statements about solvents is correct?
Q3.Which two of the following keywords can be used to describe a substance that can dissolve in a liquid?
Q4.Some pH scales have a range from 0 to 14. Which of the following would describe a substance with a pH of 0?
Q5.The pH range most commonly used is from 1 to 14. What does the term 'range' mean?
Q6.The lower the concentration of hydrogen ions in a solution, the the pH of the solution.
Assessment exit quiz
6 Questions
Q1.A pupil uses red cabbage to make an indicator. The solution produced is too pale to show a colour change. How could the method to make the indicator be improved?
Q2.Which of the following describe what a mortar and pestle are used for?
Q3.Match the following colours of red cabbage indicator to the correct type of the substance.
Q4.Which of the following statements explain why red cabbage and litmus are less effective than universal indicator at indicating the pH of a substance?
Q5.Different chemical indicators turn different colours at the same pH. Match the colour to the correct indicator if a solution has a pH of 7.
Q6.A soluble substance dissolves in a solvent. If the solvent is water, what name is given to a soluble base?
To help you plan your 9 science lesson on: Practical: red cabbage indicator solution, download all teaching resources for free and adapt to suit your pupils' needs...
To help you plan your 9 science lesson on: Practical: red cabbage indicator solution, 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.
Explore more key stage 3 science lessons from the Acids and bases unit, dive into the full secondary science curriculum, or learn more about lesson planning.