Preparation of Lyophobic Sol - Ferric Hydroxide Sol

In this article, we have discussed step-by-step procedure to perform an experiment which will help you learn how to prepare ferric hydroxide sol. Carefully read the content on this page to understand the aim, procedure and materials required to perform the experiment. Try to perform the experiment and match your result with this.

Table of Contents


The aim of this experiment – to prepare ferric hydroxide sol.


Ferric hydroxide (Fe(OH)3) has the ability to form a lyophobic sol. Sulphides or metal hydroxides which are colloidal solution, when treated with water, are termed as lyophobic colloids. Fe(OH)3 sol is obtained by hydrolysis of ferric chloride with boiling distilled water. The reaction is as follows:

\(\begin{array}{l}FeCl_{3}(aq) + 3H_{2}O(l) \overset{boil}{\rightarrow}Fe(OH)_{2}(s) +3HCl(aq)\end{array} \)

The hydrochloric acid formed during the hydrolysis destabilizes the ferric hydroxide sol and therefore must be removed through the process of dialysis.

Also Read:   Preparation of Lyophobic Sol – Ferric Hydroxide Sol Viva Questions

Materials required:

The apparatus and materials required for this experiment are as follows:

  1. Glass rod
  2. Round bottom flask
  3. Boiling tube
  4. Conical flask of 250 mL volume
  5. Tripod stand
  6. Funnel
  7. Beaker of 250 mL volume
  8. Burette
  9. Wire gauze
  10. Dropper
  11. Burner
  12. Wire gauze
  13. Iron stand with clamp
  14. Boiling tube
  15. Distilled water
  16. Solution of ferric chloride


1. Take a conical flask of volume 250 mL and steam clean it.

2. To clean the conical flask by steaming out process take the help of the figure given below.

Experimental Setup:

Preparation of Lyophobic Sol Ferric Hydroxide Sol

3. Prepare 2% solution of ferric chloride by taking 2 g of pure ferric chloride in 100mL of distilled water.

4. Take the conical flask cleaned by the steaming out process and add 100mL of distilled water.

5. Boil the water on a wire gauze.

6. Drop by drop pour 10 mL of ferric chloride solution with the help of a dropper or burette.

7. Constantly keep stirring the boiling water mixture while adding ferric chloride solution.

8. Heat the conical flask containing a mixture of distilled water and ferric chloride solution until you see a brown or deep red coloured ferric hydroxide solution.

9. Allow the mixture in the conical flask to settle at room temperature.

10. Label the flask containing the mixture as ferric hydroxide sol.

Precautions to be taken during the experiment:

  • Fe(OH)3 sol gets affected due to the presence of impurities. Therefore, to avoid this, conical flask is cleaned by steaming out process.
  • The FeCl3 solution is added drop wise.
  • Heat the mixture of distilled water and ferric chloride solution until brown or deep red colour is obtained.
  • The hydrochloric acid (HCl) formed is removed by the process of dialysis to avoid the destabilization of sol.

Viva Voce:

1. How to prepare 2% of ferric chloride solution?

Ans: Mix 2 g of ferric chloride in 100 mL of distilled water.

2. Why is it important to clean the apparatus by steaming out process?

Ans: Ferric hydroxide sol gets affected due to the presence of impurities. Hence, the apparatus is steam cleaned before the experiment.

3. Boil the mixture of ferric chloride solution and distilled water until it attains _______ or _______ colour.

Ans: Deep red or brown colour.

4. Hydrolysis of ferric chloride results in ________.

Ans: Formation of hydrochloric acid.

5. What is the quantity of ferric chloride solution added to 100 mL of boiling distilled water?

Ans: 10 mL.





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