Tyndall Effect

Aim

To observe the Tyndall effect in different types of solutions.

Materials Required

Procedure

1. Prepare a true solution by dissolving salt in water in the first beaker.
2. Prepare a colloidal solution by adding a few drops of milk to water in the second beaker.
3. Prepare a suspension by mixing chalk powder in water in the third beaker.
4. Place all three beakers side by side in a dark room.
5. Shine a laser pointer or torch light from one side so the beam passes through all three beakers sequentially.
6. Observe the path of the light beam inside each beaker.

Key Concepts

The Tyndall effect is the scattering of light as a light beam passes through a colloid. The individual suspension particles scatter and reflect light, making the beam visible.

True solution particles (< 1nm) are too small to scatter light. Colloidal particles (1-100nm) are large enough to scatter light, showing the Tyndall effect. Suspension particles (> 100nm) are very large, they heavily scatter or block light, and eventually settle down.

Precautions

• Ensure the room is dark enough to see the light beam clearly.
• Do not look directly into the laser beam as it can damage your eyes.
• Allow the suspension to sit for a minute so larger particles settle.