To Compare the Effectiveness of a Number of Emulsifying Agents in Forming Emulsions

A mixture of the dispersed phase and a dispersion medium wherein the dispersed phase remains suspended in the dispersion medium is known as a colloidal solution. In these solutions, the dispersion mediums can be water, oil, solid particles or air. Emulsions are types of colloidal solutions wherein solute and solvent are both liquids. 

Examples- milk, mayonnaise, ice-creams etc. Emulsifiers are agents present in emulsions which help stabilise the emulsions. They keep both liquids in a mixed state for a prolonged period, increasing the emulsion's shelf-life. The stabilising nature of these agents is due to their chemical structure, which contains hydrophilic and hydrophobic parts.

Table of Contents

• Aim 

• Apparatus Required

• Theory

• Observation

• Result

Aim 

To compare the effectiveness of a number of emulsifying agents in forming emulsions.

Apparatus Required

• 5 bottles with stoppers

• Measuring cylinder

• Stop-watch

• 5ml Pipettes

• Castor oil 

• 1% soap solution, sodium oleate solution, detergent, gelatine, and gum acacia

• Distilled water

Theory

Various emulsifying agents have different effects for keeping oil in an emulsified state. Emulsifiers assist in lowering the interfacial tension present between oil and water. As a result, the oil droplets do not coagulate, so the emulsion remains stable. These agents are present at the junction of the two liquids. Since all emulsifiers have different capabilities to lower the interfacial tension, these agents have different effectiveness. 

Procedure

1. Take 5 stoppered bottles, clean them, and label them as A, B, C, D and E.

2. Pour 5 ml of castor oil into all five bottles.

3. Measure 20 ml of distilled water with a measuring cylinder and pour it into the five bottles.

4. Add 5 ml of Kerosene oil, Mustard oil, machine oil, Castor oil and Coconut oil in test tubes A, B, C, D and E, respectively, one by one. 

5. Shake the bottles vigorously for 1 minute and keep them standing.

6. Note the time taken for the two liquid solutions to separate.

7. Record your observations.

Observations 

Result

The result of the above experiment states that:-

1. Coconut Oil takes the maximum time to separate both liquids in the presence of an emulsifier/emulsifying agent. Hence it is rated as 1.

2. Machine Oil takes the minimum time to separate both liquids in the presence of an emulsifier/emulsifying agent. Hence it is rated as 5.

Effectiveness of a number of emulsifying agents

Precautions

1. Do not perform the above experiment simultaneously for all the bottles, as noting the time of all the bottles together may not be accurate.

2.  Pour equal drops of emulsifying agents into all the bottles.

3. Shake all the bottles for the same duration.

4. Start the stopwatch post-shaking immediately and stop the stopwatch immediately after the two layers are separated.

Lab Manual Questions

1. Why do the bottles containing the oil and water need to be shaken vigorously?

Ans: Shaking the bottles vigorously helps to mix all the contents of the bottles properly. It allows oil and water to be mixed properly with the emulsifier and helps in the formation of a stable emulsion.

2. Describe gelatin.

Ans: Gelatin is a common type of emulsifying agent. Its applications are seen in food, pharmaceutical, medical and technical fields. Gelatin is a good surfactant and hence reduces the surface tension of water to a great extent. Owing to this property of gelatin, it is considered a good emulsifying agent.

3. What are the properties of emulsion?

Ans: Emulsions are liquid-liquid colloidal solutions and hence show all the properties of colloidal solutions such as Brownian movement, Tyndall effect and Electrophoresis. When electrolytes are added to emulsions, they tend to coagulate and separate from each other.

4. What is emulsification?

Ans: The process wherein one liquid forms small droplets into another liquid. i.e. when one liquid remains suspended in another liquid, such that both of them do not mix completely with each other, is known as emulsification. 

Viva Questions 

1. What are the dispersed phase and dispersion medium in the above experiment?

Ans: Oil is the dispersed phase since it is present in less quantity, and water is the dispersion medium as it is present in more quantity.

2. What is meant by the emulsification of fats?

Ans: The breakdown of large fat molecules into small fat droplets easily dissolved in water is known as the emulsification of fats.

3. Name an effective emulsifying agent used.

Ans: Glycerol monostearate (GMS) and polyglycol esters are commonly used emulsifying agents.

4. What is a criterion for a good emulsifier?

Ans: A good emulsifier should be

• Physically and chemically stable

• Inert and compatible with other members of a product

• Non-irritant and non-toxic in nature

5. What is gum acacia?

Ans: Gum acacia is a natural gum obtained from the hardened sap of tree species and is used as an emulsifier, texturing agent and stabilizer.

6. What are the side effects of emulsifiers?

Ans: When emulsifiers are consumed in excess amounts then it might lead to diarrhoea, stomach ache, vomiting feeling and bloating.

7. Define non-emulsifiers.

Ans:  Non-emulsifiers are chemicals which destabilize emulsions and help in the separation of two liquids from one another.

8. What is coalescence?

Ans: When small oil droplets bump into each other and combine to form a large droplet which destabilizes, the emulsion is known as coalescence.

9. Explain the types of sols present

Ans: Sols are of two types- lyophilic which is solvent loving and lyophobic which is solvent repelling.

10. Give examples of emulsifiers.

Ans: Diacetyl tartaric acid ester of monoglyceride, and sodium stearoyl lactylate, sodium phosphates are a few examples of emulsifiers.

Practical Based Questions (MCQs)

1. Emulsions are of two types, ______and _____

1. Oil in water, water in oil 

2. Oil in oil, water in water.

3. Water and air

4. Water in air and air in water

Ans: Oil in water, water in oil 

2. Emulsifying agents are 

1. Have affinity towards Hydrophobic compounds

2. Have affinity towards Hydrophilic compounds

3. Both A and B

4. None of the above

Ans: Both A and B

3. Which one is not an emulsifying agent?

1. Salt

2. Gelatin

3. Soap

4. Lecithin

Ans: Salt

4. Whisking and blending action help in______

1. Bring oil droplets nearby

2. Dispersing the oil in the liquid

3. Make the emulsion coagulate

4. All of the above

Ans: Dispersing the oil in the liquid

5. The best natural emulsifier is

1. Beeswax

2. Sodium phosphates

3. Mono and diglycerides

4. Both A and B

Ans: Beeswax

6. Find the odd man out

1. Gelatin

2. Sodium ions

3. Soaps

4. Gums

Ans: Sodium ions

7. ______is the rising up of the colloidal particles due to buoyancy or due to_____force which breaks an _____.

1. Flocculation, centrifugal, colloidal solution

2. Creaming, centripetal, true solution

3. Creaming, centripetal, emulsion

4. Flocculation, the centrifugal, true solution

Ans: Creaming, centripetal, emulsion

8. Find the true statement.

1. Colloidal solutions are true solutions

2. A homogeneous solution shows the Tyndall effect

3. Hydrophilic sols are water-loving sols

4. Lyophobic sols are only water-repelling sols

Ans: Hydrophilic sols are water-loving sols

9. An emulsion contains_____, _____and _____

1. Oil, water, emulsifier

2. Water, alcohol, sol

3. Water, salt, emulsifier

4. Water, sugar, sol

Ans: Oil, water, emulsifier

10. Which of the following gives oil in water type of emulsion?

1. Protein

2. Milk

3. KCl in water

4. Both A and B

Ans: Both A and B

Conclusion

From the above experiment, we can conclude that emulsifiers are chemical components which keep the oil-water emulsion in an emulsified state for a long duration. This property of these agents is because emulsifiers have both hydrophobic and hydrophilic tails, which helps them to stabilize emulsions and prevent flocculation and coalescence in the emulsion. The best emulsifying agent from the above is ______ and keeps the solution stable for ______time period. Common examples of emulsifiers are lecithin, soy lecithin, mustard, etc.