Question

Describe an experiment to identify suspensions and colloids.

Answer 1

• Take some chalk powder in a test tube. 
• Take a few drops of milk in another test tube. 
• Add water to these samples and stir with a glass rod. 
• Now do the following steps and write your observations in the table given.

Step 1 : 

Direct a beam of light from a torch or a laser beam on the test tubes. Observe the path of the light through the solutions. 

Step 2 : 

1.  Leave the mixture undisturbed for some time. 
2.  See whether the solute settles down after some time. 

Step 3 : 

Filter the mixtures and observe any residue found on the filter paper. 

Now read your observations :

Mixture	Is the path of the beam of light beam visible ?(Yes/No)	Did solute settle down ? (Yes/No)	Residue is seen on the filter paper (Yes/No)
Chalk mixture	Yes	Yes	Yes
Milk mixture	Yes	No	No

Observations : 

1.  In the chalk mixture, the particles of chalk settled at the bottom of the test tube and on filtration, we can observe a residue on the filter paper. 
2.  Hence the chalk mixture is a suspension. 
3.  In the milk mixture, the particles of milk are uniformly spread throughout the mixture and no residue is found on the filter paper. 
4.  Hence milk mixture is a colloidal solution.