Change of colours in ACIDS AND BASES – Class 7 Science Experiment

Chapter Name: ACIDS AND BASES

Activity Name: Change of colours in ACIDS AND BASES

Activity Description:

Required Items:

1. Turmeric powder
2. Water
3. White paper
4. Pencil
5. Brush
6. Soap water (water mixed with soap)
7. Lime water (water with a few drops of lime juice)

Step by Step Procedure:

1. Take some turmeric powder and add a bit of water to it to prepare a turmeric paste.
2. Rub the turmeric paste on a white paper to create a surface with turmeric color.
3. Use a pencil to draw a flower on the paper with the turmeric paste.
4. Color the flower on the paper with soap water using a brush.

Experiment Observations:

1. Observations after coloring the flower with soap water:
   • The color of the flower changes when soap water is applied to it.
2. Take some lime water and add a few drops of it on a separate piece of turmeric paper.
3. Observe the color change on the turmeric paper due to the lime water.

Precautions:

1. Be careful while handling lime water, as it can be mildly caustic. Avoid direct contact with skin and eyes.
2. Conduct the experiment on a surface that can be easily cleaned, as turmeric may stain certain materials.

Lesson Learnt from Experiment:

The experiment demonstrates the effect of acidic and basic substances on turmeric color. Turmeric contains natural pH indicators, such as curcumin, which change color depending on the pH of the substance they come into contact with.

The color change in the flower when soap water is applied indicates a reaction with the basic components of the soap, while the color change on the turmeric paper with lime water indicates a reaction with the acidic components of lime. This experiment highlights the use of turmeric as a natural pH indicator and provides an engaging way to learn about the properties of acids and bases.