Turmeric Test Strips
✨ Yellow turmeric paper turns deep red in soapy water and stays yellow in lemon juice, sorting your kitchen into two families.
🧰 You need
- one teaspoon of turmeric powder
- water
- white paper cut into strips
- a cotton bud or brush
- lemon juice and vinegar
- baking soda solution and soapy water
⚠️ Keep all test liquids away from your eyes and wash your hands afterwards.
👀 What you will see
Lemon juice and vinegar leave the strip the same yellow it already was. Baking soda solution and soapy water turn it a strong red-brown. Plain water gives no change, which is your control.
🧪 Do it
- Mix the turmeric with a little water to make a thin paste.
- Paint the paste evenly along your paper strips and dry them completely.
- Line up small amounts of each test liquid in separate spoons or lids.
- Dip a fresh strip into each liquid and lay it down beside its label.
- Record the colour you see for every liquid.
- Sort the strips into two groups and order each group from weakest to strongest colour change.
💡 Why it happens
Turmeric contains a dye called curcumin that changes shape, and therefore colour, depending on the acidity of its surroundings. A dye that reports acidity by changing colour is called an indicator. Acids such as lemon juice and vinegar leave curcumin yellow; alkalis such as baking soda and soap solution turn it red. Chemists put this on a scale called pH, where numbers below seven are acidic, seven is neutral and above seven is alkaline.
🔁 Now try this
Test six more household liquids, then rank all of them from most acidic to most alkaline and compare your order with a published pH chart.
🤔 Think about it
Why does a turmeric stain on a shirt turn red the moment you rub soap on it?
🧘 Ask the Acharya
“Why does a turmeric stain on a shirt turn red the moment you rub soap on it?” — ask him and he will explain it from your own chapters.
More for Std 6–8
Density Tower
Four kitchen liquids sit in four separate stripes in one glass, and a grape parks itself halfway down.
Try it →Science25 minMagnet With a Switch
An ordinary iron nail picks up a pile of paper clips and drops every one of them the instant you break the circuit.
Try it →Science25 minYeast Blows Up a Balloon
A spoonful of dried powder, fed nothing but sugar, inflates a balloon while you watch.
Try it →