To Prepare a True Solution and Observe the Tyndall Effect (Class 9 Chemistry Practical)
To prepare a true solution and distinguish it from a colloid by observing the Tyndall effect.
TL;DR: To prepare a true solution and distinguish it from a colloid by observing the Tyndall effect.
Written & reviewed by the Syllab.in Academic Team (CBSE/NCERT subject experts) · Updated
Aim: To prepare a true solution and distinguish it from a colloid by observing the Tyndall effect.
Materials Required
- Copper sulphate crystals
- Distilled water
- Test tube
- Stirring rod
- Beam of light (torch/laser)
- Colloidal solution (starch or ink)
- Beaker
Theory
A true solution is a homogeneous mixture where solute particles are completely dissolved and have a diameter less than 1 nanometer. Colloids have particle size between 1-1000 nanometers. The Tyndall effect is the scattering of light by colloidal particles; true solutions do not show this effect as solute particles are too small to scatter light.
Procedure
- Take a test tube and add distilled water
- Add copper sulphate crystals to the water and stir thoroughly until all crystals dissolve
- Observe the color of the solution - it should be clear and uniform
- Hold the test tube against light and observe if it appears clear from the side
- Shine a torch or laser beam through the copper sulphate solution and observe whether the path of light is visible
- Now prepare a colloidal solution by mixing starch with water
- Pass a torch beam through the colloidal solution and observe if the path of light is clearly visible
- Compare the two observations
Observation
The copper sulphate solution is clear, uniform in color, and appears transparent when viewed against light. When a torch beam passes through the true solution, the path of light is NOT visible. In contrast, the colloidal starch solution appears cloudy, and the path of light IS clearly visible as a bright cone (Tyndall effect).
Result
The copper sulphate forms a true solution where the Tyndall effect is absent, confirming that solute particles are too small to scatter light. The colloidal starch solution shows the Tyndall effect, indicating larger particle size.
Precautions
- Use distilled water to avoid impurities
- Stir thoroughly until all solute dissolves completely
- Perform the Tyndall effect observation in a dark room for clear observation
- Use a bright light source for better visibility of the effect
- Do not heat the solution unless specified
Viva Questions
What is the difference between a true solution and a colloid?
A true solution has solute particles smaller than 1 nanometer, while a colloid has particle size between 1-1000 nanometers.
What is the Tyndall effect?
The Tyndall effect is the scattering of light by colloidal particles, making the path of light visible.
Why do true solutions not show the Tyndall effect?
True solutions do not show the Tyndall effect because the solute particles are too small to scatter light.
What color is a copper sulphate solution?
A copper sulphate solution is blue in color.
More Class 9 Chemistry Practicals
- To Find the pH of Samples Using Indicators
- To Study a Double Displacement (Precipitation) Reaction
- To Test Acids and Bases with Indicators
- To Verify the Law of Conservation of Mass
- To Study the Effect of Temperature on Reaction Rate
- To Determine Melting and Boiling Points of a Pure Substance
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