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What is Turmeric Paper?
It is yellow paper made by dipping filter paper in turmeric paste .
- Turmeric paper can test basic substances only.
- Turmeric paper cannot differentiate between acidic and neutral substances .
- Basic substances turn turmeric paper from yellow to red .
- Olfactory indicators change odour in acidic or basic medium .
Activity 2.3: Preparing and Using Turmeric Paper
What you need:
- Turmeric (haldi)
- Petri dish or container
- Water
- Filter paper
- Dropper
- Samples from Activity 2.1
What to do:
- Step 1: Take a spoonful of turmeric in a petri dish or container and add a little water to make a paste
- Step 2: Carefully dip a piece of filter paper in the turmeric paste until it gets yellow colour
- Step 3: Take it out and allow it to dry
- Step 4: Cut this yellow paper into thin strips, which are used as 'turmeric paper'
- Step 5: Using a dropper, put a drop of each sample used in Activity 2.1, one by one, on separate pieces of turmeric paper
- Step 6: Record your observations
Observations
What you see:
| Substance | Turmeric Paper Colour | Nature |
|---|---|---|
| Soap solution | Turns red | Basic |
| Baking soda solution | Turns red | Basic |
| Lime water | Turns red | Basic |
| Washing powder solution | Turns red | Basic |
| Lemon juice | Remains yellow | Acidic |
| Vinegar | Remains yellow | Acidic |
| Tap water | Remains yellow | Neutral |
| Sugar solution | Remains yellow | Neutral |
Why this happens:
We have studied that turmeric contains natural pigments that react only with bases . This is why it can identify basic substances but cannot differentiate between acidic and neutral substances.
- Basic substances cause chemical change in turmeric pigment
- Acidic and neutral substances do not react with turmeric
Activity: Testing Olfactory Indicators
What you need:
- Finely chopped onions
- Container with lid
- Clean cotton cloth or filter paper strips
- Tamarind water
- Baking soda solution
What to do:
- Step 1: Take some finely chopped onions in a container, along with some strips of clean cotton cloth or filter paper
- Step 2: Tightly close the container and leave it overnight
- Step 3: Take two cotton cloth or filter paper strips from the container and check their odour
- Step 4: Keep them on a clean surface and put a few drops of tamarind water on one strip and a few drops of baking soda solution on the other
- Step 5: Allow the drops to spread on the strips
- Step 6: Check the odour again
Observations
What you see:
- Original onion smell on both cloth strips
- Tamarind water strip loses onion smell
- Baking soda strip loses onion smell
- Different final odours on each strip
Why this happens:
We have studied that olfactory indicators are substances whose odours change in acidic or basic medium . This is why onion-soaked strips smell different when treated with acids and bases.
- Onion compounds react with acids and bases
- Chemical reactions change odour molecules
Section Summary: Nature - Our Science Laboratory
