Chemical reactions, acids and alkalis
Making your own pH indicator
Where do kitchen liquids sit on the pH scale?
Watch first
An English teaching video on this topic from Archie Science Show. Watch it, then scroll down for the lesson.
What you need
Tick each one as you find it — 0 of 4 ready.
Stay safe: An adult pours the hot water. Never taste anything, and keep soap away from your eyes.
Plan the fair test
- Change: Which liquid you test
- Measure: The colour of the indicator
- Keep the same: Volume of indicator and volume of test liquid
Objectives this evidences
- Understand reactions of acids with alkalis to produce a salt plus water, and use the pH scale for measuring acidity
Do it, one step at a time
Step 1 of 4
- Step 1. Tear up red cabbage, cover with hot water and leave to cool. Strain off the purple liquid.
- Step 2. Put an equal splash of indicator into each glass.
- Step 3. Add a teaspoon of one test liquid to each glass and record the colour.
- Step 4. Put your liquids in order from most acidic to most alkaline using the colours.
What should happen
Acids go pink or red, neutral stays purple, alkalis go blue, green or yellow.
Think about: Add vinegar to the bicarbonate glass. What does the colour change tell you about neutralisation?
Write up your result
A sentence or two is enough to save it.
The lessons behind this practical
Each one opens with the same short film, and the film has a written transcript underneath if reading is easier than watching.
Now the quiz for this topic
Questions come from the lessons behind this practical, so nothing is asked that has not been taught.
Quiz
Chemical reactions, acids and alkalis quiz
4 questions from the lessons in this stage. No timer, and you can try again as many times as you like.