Ok, I shall present this answer in the way you are expected to write in your Laboratory Notebook.


Aim of the Experiment - 

To prepare colloidal solution of starch


Theory - 

Starch forms a lyophilic sol when water is used as the dispersion medium. Lyophilic sols are those in which the dispersed phase (in this case, starch) exhibits a definite affinity for the dispersion medium (in this case, water). Heating accelerates the sol formation. By heating starch and water at about 100 degrees celcius, the starch sol can be prepared. The sol is quite stable and is not affected by the presence of any electrolytic impurity.


Apparatus Required -

1. Beakers (50mL, 250mL)

2. Glass rod

3 Funnel

4. Filter paper

5. Pestle and mortar

6. Tripod stand

7. Wire gauze

8. Bunsen burner


Chemicals - 

1. Soluble starch (500mg)

2. Distilled water


Methodology - 

1. 500 mg of starch was taken in a mortar.

2. To it, few mL of distilled water was added.

3. The starch was ground to make a thin paste.

4. This paste was transferred to a 50 mL beaker.

5. 100 mL of water was taken in a 250 mL beaker and this beaker was heated so that water started boiling.

6. While stirring the boiling water, the paste was poured into boiling water in the beaker.

7. The boiling was continued for 10 minutes and then, the beaker was allowed to cool.

8. The content of the beaker was filtered through a filter paper, fixed in a funnel. 

9. The filtrate was labelled as "Starch Sol".


Precautions - 

1. Distilled water should be used and not tap water.

2. Apparatus should be clean.

3. Starch should be converted into a fine paste before adding to boiling water.

4. Starch paste should be added in a thin stream to boiling water.

5. Constant stirring of the contents is necessary during the preparation of the sol.


Thank You

Best Of Luck