To show turmeric as an acid-base indicator.

Materials:

1.     Glass bowl

2.     Water

3.     Turmeric

4.     Detergent powder

5.     Lemon

Method:

Take a glass bowl mix turmeric powder with water

Now the colour of the mixture is yellow.

Add some detergent powder and stir it.

Now we  see that the colour has changed to red-orange.

Add half of lemon to it and we see the colour changes back to original yellow colour

 

Observations:

Turmeric only changes colour in the presence of a base, and not in the presence of an acid.

Yellow turmeric changes to red-orange when dropped into soap solution, indicating that the soap solution is basic. When acidic lemon juice is slowly added to this, the red-orange gradually weakens and the original yellow is seen again, showing that the acidic lemon juice reacted with the basic soap solution, and turned the liquid to neutral

 

 

Conclusion:

Indicator is a substance that changes its colour depending on the pH value of a liquid. Bases such as a soap solution have a pH value greater than 7, whereas acidic liquids like lemon juice have a pH value less than 7. 

This activity works based on the principle of force. The air trapped inside the balloon pushes out the open end, causing the balloon to move forward.