Formation of grains of sulphur in Human Eye and Colourful World – Class 10 Science Experiment

Chapter Name: Human Eye and Colourful World

Activity Name: Formation of grains of sulphur in Human Eye and Colourful World

Activity Description:

This experiment aims to observe the formation of grains of sulphur through a chemical reaction between sodium-thio-sulphate (hypo) and sulphuric acid in the presence of sunlight. The experiment also demonstrates the phenomenon of light scattering and its impact on the color perception of the sulphur grains.

Required Items:

1. Sodium-thio-sulphate (hypo) solution
2. Sulphuric acid
3. Glass beaker
4. Access to an open place with abundant sunlight

Step by Step Procedure:

1. Take a glass beaker and pour the sodium-thio-sulphate (hypo) solution into it.
2. Add some sulphuric acid to the beaker.
3. Place the beaker in an open area where there is ample sunlight.
4. Observe the changes in the beaker and the formation of grains of sulphur as the reaction progresses.

Experiment Observations:

• Sulphur precipitates as the reaction proceeds.
• Initially, the grains of sulphur are small in size and appear blue in color due to their size being comparable to the wavelength of blue light.
• As the reaction continues, the size of sulphur grains increases, and their color changes to white due to scattering of light.
• The larger grains act as scattering centers for other colors, resulting in a combination of all colors, which appears white.

Precautions:

1. Handle sulphuric acid with care, as it is a corrosive and dangerous substance. Wear appropriate protective gear such as gloves and goggles.
2. Conduct the experiment in a well-ventilated area to avoid inhaling any harmful fumes.
3. Place the beaker in a safe location where it will not be easily disturbed or knocked over.
4. Keep children away from the experiment and provide supervision if necessary.

Lesson Learnt from Experiment:

This experiment illustrates the phenomenon of light scattering and how the size of particles can influence the colors we perceive. Initially, the smaller sulphur grains appear blue, but as they grow larger, they scatter light of various colors, resulting in the perception of white color. This experiment provides valuable insights into light interaction with matter and its effects on color appearance.