First chemistry (grades 7–8) · Grade 8
Kitchen indicator: red cabbage
ChemAI · Worksheet
NameClassDate
Aim
Red-cabbage juice changes colour in acids and in bases.
Before you start: what do you predict will happen? Why?
What you do
| Step | What I observed | |
|---|---|---|
| 1 | Add vinegar (ethanoic acid) to tube 1: acids turn it red-pink. | |
| 2 | Add washing soda (sodium carbonate) to tube 2: bases turn it green-blue. | |
| 3 | Leave tube 3 as it is (neutral, purple) and turn on the pH meter to compare. |
Questions
- Write a word or symbol equation for one reaction you observed.
- Explain your most important observation using particles, ions or energy.
- Was your prediction right? What would you change to get a more reliable result?