How to prepare and identify a homogenous mixture and a heterogeneous mixture? CLASS 9 SCIENCE PRACTICAL

CLASS IX, X , XI , XII , NEET and JEE

 ACTIVITY :- 1

  How to prepare and identify a homogenous mixture and a                   heterogeneous mixture?

 REQUIREMENT :- 

Sodium chloride/sugar, sand/chalk powder, water, micro beaker, stirring rod, funnel, filter paper, tripod, starch powder and kerosene burner (milk)

PROCEDURE:-

Part A:-

How to prepare a homogenous mixture (true solution)?

1. Take 50 mL of water in a 100 mL beaker and add one spatula full of sodium chloride/ sugar to it.

 2. Stir it well and filter.

3. What do you observe on the filter paper?

4. Do you observe any particles settling down in the solution?

Part B :-

How to prepare a suspension?

1. Take 50 mL of water in a100 ml beaker and add one spatula of sand/chalk powder to it.

2. Stir it well and observe carefully.

3. Filter the solution through a filter paper.

4. What do you observe on the filter paper?

Part C :-

 How to prepare a colloidal solution? (Milk natural colloidal solution)

1. Take one spatula of starch powder in a 100 mL  beaker and make its paste with water.

2. Add the paste gradually by constant stirring to another beaker containing 5 mL water.

 3. Heat the mixture with constant stirring. Do not boil.

4. Cool it and filter.

5. What do you observe on the filter paper? 

Do you observe some turbidity in the filtrate?

 In this colloidal solution, you cannot see the particles of starch, whereas you could see the particles of sand in the suspension. The particles in colloids are so small that you cannot see them with naked eyes. But you can prove them to be present when a  beam of light is passed through the solution. These become visible by scattering the light. Mixture in Part A is homogeneous mixture. Mixture in Part B and Part C are heterogeneous mixtures

 

Milk

Starch Solution

Chalk Solution

  NaCl sloution       

When a beam of light is passed through milk solution, then the beam of light get scattered through the milk solution and the path of light becomes visible in the milk solution because milk solution is the COLLOIDAL solution.( in colloidal solution the size of particles is Less Than from 1000nm  its enough to scatter a light and path of light visible Blue color )

And Scattering of beam of light in the colloidal solution is called TYNDAL EFFECT.

Related Experiment Video 👇👇

What have you learnt?

1. Salt/sugar in water forms a homogenous mixture.

2. Sand/Chalk powder in water forms a heterogenous mixture.

3. The residue was seen on the filter paper in case of heterogenous mixture.

4. The homogenous solution is transparent.

5. Suspensions are opaque.

6. Suspended solid can be separated by filtration.

7. Colloidal solutions are translucent and make a heterogeneous mixture.

8. Solid particles of a colloidal solution cannot be separated by filtration.

9. The enamel paint is an example of heterogeneous mixture and colloidal solution.