Preparation of Lyophilic Sol - Starch

In this article, we have given step by step procedure to perform an experiment which will help you understand how to prepare colloidal solution of starch. Read the article carefully to understand the aim, procedure and the apparatus required for the experiment. Conduct the practical and try to match the result with this.

Aim:

Preparation of lyophilic sol of starch.

Theory:

When water is used as a dispersion medium, starch has the ability to form sol. This formation is enhanced with the help of heating. To prepare sol the mixture of water and starch is heated to about 100° C.

Materials required:

  1. Tripod stand
  2. Beaker of about 50 to 250 mL
  3. Funnel
  4. Distilled water
  5. Wire gauze
  6. Glass rod
  7. Pestle and mortar
  8. Burner
  9. Filter paper
  10. 500 mg starch

Procedure:

  1. Take a mortar and add 500 mg of starch to it.
  2. Pour a few drops of distilled water and pestle the starch into a thin paste.
  3. Transfer the grinded paste to a 50 ml beaker.
  4. Take a 250 mL beaker and pour 100 mL of distilled water to it and heat the water to boiling.
  5. Slowly pour the paste into the boiling water and constantly keep stirring with the help of glass rod.
  6. Let it boil for 10 minutes after you have transferred all the paste into the beaker.
  7. Allow it to cool.
  8. With the help of a filter paper attached to a funnel you can filter out the contents.
  9. Label the filtrate as starch sol.

Precautions to be taken during the experiment:

  • The apparatus used for the experiment should be washed with distilled water and dried before conducting the experiment.
  • Use of distilled water to prepare starch sol.
  • Make sure to convert starch into a smooth paste before adding to the boiling water beaker.
  • Keep constantly stirring the mixture while preparing starch sol.

Viva Voce:

1. What is starch mixed with?

Ans: Distilled water.

2. The starch and distilled water is heated to what temperature?

Ans: 100° C.

3. How much amount of distilled water is taken to prepare 500 mg of starch sol?

Ans: 100 mL

4. Pour the paste into cold distilled water before boiling. True or false?

Ans: False.

5. Constantly keep stirring the water in the beaker while adding the paste. True or false?

Ans: True.

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