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Role of emulsifying agents in stabilising emulsions of oils

In this article, we have discussed the procedure to perform an experiment to study the role of emulsifying agents in stabilizing the emulsions of different oils. This article will help you understand the procedure to conduct the experiment. Conduct the experiment, observe, and record the results.


The aim of this experiment – Studying the role of emulsifying agents to stabilise the emulsions of different oils.


A colloid where the dispersion medium, as well as dispersed phase, are in liquid form is called an emulsion. Here they are differentiated based on their relative amounts. Dispersed phase is present in smaller quantity whereas the dispersion medium is present in a large proportion.

Mix oil and water and shake the mixture. You can see a slight milky solution. It is unstable and is known as an emulsion of oil in water. When allowed to stand, two layers are formed separating oil and water.

To increase the stability of oil and water emulsion, soap solution can be added. Soap solution is an emulsifying agent. The carboxyl polar group decreases the interfacial surface tension between the two layers. Optimum concentration is the soap concentration which is essential to complete emulsification process. Effective stabilisation is not achieved if the amount is greater or less than optimum concentration.

Materials required:

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

  1. One test tube stand
  2. Stopwatch
  3. One glass rod
  4. Five droppers
  5. Detergent or soap 5 g
  6. Linseed oil, mustard oil, machine oil, and castor oil 10 mL each
  7. Six test tubes


  1. Take a test tube with 10 mL of distilled water and dissolve 1 g of detergent in it. Shake the test tube vigorously and label it as ‘A’.
  2. Take four test tubes and label them B, C, D and E. Add 5 mL distilled water in each test tube. Pour 10 drops of mustard oil in B, 10 drops of linseed oil in C, 10 drops of castor oil in D and 10 drops of machine oil in E.
  3. Take test tube B in your hand and shake it vigorously (for 5 minutes) and keep it in the test tube stand. Start the stopwatch to record the time taken to separate two layers.
  4. Follow the same procedure with the rest of the test tube’s viz, C, D and E.
  5. Add two drops of detergent or soap solution prepared in test tube A into each test tube. Shake the test tubes for 5 minutes each and record the time of separation.
  6. Record the results in the table below.
Specification of test tube Oil used for emulsification Without soap or detergent With soap or detergent

Precautions to be taken during the experiment:

  • Add an equal amount of detergent solution to all five test tubes.
  • Shake all five test tubes for an identical time span to minimise the time recording error.
  • Stop the stopwatch immediately when you see the layers separated and start it as soon as the shaking stops.

Viva Voce:

1. How to prepare a detergent solution?

Ans: Add 10 mL of distilled water in a test tube and dissolve 1 g of detergent.

2. What is the quantity of mustard oil added?

Ans: 10 drops.

3. When to start the stopwatch to record separation time?

Ans: As soon as you finish shaking the test tube.

4. When to stop the stopwatch to record separation time?

Ans: As soon as you see the layers separating.

5. How many test tubes are required for this experiment?

Ans: 5.

Test Your Knowledge On To Study The Role Of Emulsifying Agents In Stabilising The Emulsions Of Different Oils!

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