Free PDFGrade 4 · Science · 45 min
Magic turmeric painting
Paint invisible pictures with baking soda and make them appear with turmeric.
I can use turmeric as a pH indicator to tell acids and bases apart.
A science experiment video with a free worksheet and answer key for teachers
About the video
In the video a hidden picture painted with baking soda water appears when turmeric is brushed over it. At home your child paints a pattern with baking soda water, lets it dry, paints turmeric over it, and then tests vinegar, lemon juice, water and soapy water on a second turmeric sheet.
Turmeric is a natural pH indicator: it stays yellow in acids and neutral liquids and turns red-brown at about pH 8 and above. Baking soda water is about pH 8, so the hidden picture turns red-brown, and a drop of vinegar turns it yellow again.
What your child learns
- Use turmeric as a pH indicator
- Sort liquids into acid, neutral and base
- Read the pH scale from 0 to 14
What's on the worksheet
- 1Predict first
- 2Test the liquids
- 3What did you see?
- 4The science behind it
- 5Key words
- 6Acid or base?
- 7pH maths
- 8True or false
- 9Explain it
You need
1 teaspoon turmeric, 2 teaspoons baking soda, 150 ml water, 2 cups, 2 brushes, 2 sheets of thick white paper, newspaper, an apron. To test: vinegar, lemon juice, water, soapy water from a bar of soap.
Safety
Turmeric stains skin, clothes and tables. Wear an apron. Keep vinegar and lemon juice away from your eyes.
Tip for the adult
Wait the full 15 minutes for the baking soda to dry before painting the turmeric on, or the picture gets blurry.
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