Question

From which substances natural indicators are prepared? Explain any one in detail with the procedure.

Answer 1

Hint: They are generally obtained from natural substances which may be a plant, an animal, or any food item.

Complete answer
Natural indicators are a type of indicator that can be found naturally and can determine the acidity and basicity of a substance. The indicators change their properties when they come in contact with an acidic or basic solution, thus detecting the.
There are various types of natural indicators, they are listed below:
> Litmus - it is made from the solution of various dyes which are naturally obtained from the lichens. It changes color in different solutions. In water, the color of litmus remains the same. In acidic solution changes its color to red while in basic solution its color changes to blue.
> Flowers - the solution of some flowers like china rose is used to detect acidity and basicity of the solution. When the solution is basic, the color of the china rose changes to green while when the solution is acidic the color becomes bright pink.
> Turmeric - It is the most common natural indicator which can be easily available. The solution of turmeric is applied on papers and from it paper strips are made.

The procedure of making turmeric paper Indicator
- Take some turmeric powder and mix it in water to form a thin paste.
- Apply this paste on the filter paper and let it dry for some time.
- After drying, cut the paper into strips.
- These strips can be used to detect the acidic or basic nature of the solution.
- When the acidic solution is present it changes its color to yellow while in the presence of basic solution it changes its color to brownish red.

Note: Flowers like hydrangeas act as the natural indicators, they help in determining the acidity or basicity of the soil. If the soil is acidic then the plant will bear deep blue flowers and if the soil is basic then the plant will yield deep pink flowers. The color of the flowers depends upon the intensity of acidity or basicity of the soil.