Emulsification - Meaning, Definition, Types, Properties, Application, FAQs

Emulsification

Although oil and water are incompatible, milk is an example of a combination in which oil (fat) particles are suspended in water. Emulsions are the name for these kinds of combinations. An emulsion is a combination of two or more liquids that are ordinarily incompatible. The term emulsion refers to a mixture in which the dispersed phase and the dispersion medium are both liquids. Even though an emulsion is a kind of colloid. This does not mean that all colloids are emulsions. It is not necessary for both the dispersed phase and the dispersion medium to be liquid in a colloidal solution. Aerosol, for example, is a colloidal solution in which the dispersion medium is a gas and the dispersed phase is a liquid (examples: clouds, fog, etc.). Emulsion is derived from the Latin word emulgere, which means "to milk out."

Examples of Emulsion

The examples of emulsions include substances like Milk, mayonnaise, hand creams and lotions, Latex, cutting fluid,etc.

Mechanism of Emulsification

The process of emulsification involves both physical and chemical mechanisms. It can be explained using the following theories:

1. Surface Tension Theory

According to this theory, emulsification occurs when the interfacial tension between the dispersed phase and the dispersion medium is reduced by an emulsifying agent. Lower interfacial tension allows one liquid to break into fine droplets and remain suspended.

2. Repulsion Theory

This theory states that the emulsifying agent forms a protective film around the dispersed phase droplets. Due to repulsive forces between these coated droplets, they do not coalesce and thus remain uniformly dispersed in the medium.

3. Film Formation Theory

The emulsifying agent forms a thin, stable film around the globules of the dispersed phase. This film prevents droplets from coming together, thereby stabilizing the emulsion.

Role of Viscosity in Emulsification

Some emulsifying agents increase the viscosity of the dispersion medium. When viscosity increases, the movement of dispersed droplets decreases, helping them remain suspended and improving the stability of the emulsion.

Properties and Characteristics of Emulsification

Emulsions have a dispersed phase as well as a dispersion medium.

• The term "interface" refers to the boundary between the dispersion phase and the dispersed medium.

• They appear to be cloudy.

• Depending on the dilution, they take on a variety of colours.

• If an emulsion scatters light evenly, it appears white. It will appear blue if it is diluted, while it will appear yellow if it is concentrated.

• The Tyndall effect is demonstrated by emulsions.

• In emulsions, the particle size of the dispersed phase can vary.

• Because emulsions are inherently unstable, they require exposure to high-energy and high-power ultrasound to generate a stable emulsion.

• On a tiny length scale, emulsion particles produce dynamic inhomogeneous structures.

Related Topics Link

• Thin Layer Chromatography
• Paper Chromatography
• Column Chromatography

Types and Variations of Emulsions

Emulsions can be classified into two types:

1. Emulsions that are easy to make- Simple emulsions

2. Emulsions with a Complex Structure- Complex emulsions

3. Simple Emulsions - Simple emulsions are emulsions that are created by scattering oil in water or dispersing water in oil. The following two types of simple emulsions can be distinguished:

4. An emulsion of water in oil

5. Emulsion of oil and water

6. Water in oil emulsion

These sorts of emulsions are known as water-in-oil emulsions because the dispersed phase is water and the dispersion medium is oil. W/O emulsions are another name for this type of emulsion. Water is an internal phase in these emulsions, while oil is an exterior phase. Water in oil emulsions can be found in the form of cold cream, butter, and so on.

1. Oil in water emulsion: When the emulsion's dispersed phase is oil and the dispersion medium is water, the emulsion is known as an oil in water emulsion. O/W emulsions are another name for this type of emulsion. Water droplets encasing oil droplets are disseminated in the oil phase in various forms of emulsions.

2. Complex Emulsions - Multiple emulsions are another name for complex emulsions. A complicated system exists in these sorts of emulsions, in which both oil in water and water in oil emulsion coexist and are stabilised by surfactants. These can be classified into the following categories:

3. Water in oil: Water in oil emulsions are also referred to as W/O emulsions. Oil droplets containing water droplets are dispersed in water in several forms of emulsions. These are actually O/W and W/O emulsions in a double emulsion.

Also Read:

• NCERT solutions for Class 12 Chemistry Chapter 5 Surface Chemistry
• NCERT Exemplar Class 12 Chemistry Solutions Chapter 5 Surface Chemistry
• NCERT notes Class 12 Chemistry Chapter 5 Surface Chemistry

Emulsifiers

Emulsifiers, also known as emulsifying agents or emulgents, are a type of chemical An emulsifying agent is a chemical that is employed in an emulsion to stabilise it by enhancing its kinetic energy. Emulsifiers are substances that have a polar or hydrophilic (or lipophilic) component that is water soluble and a non-polar or hydrophobic (or lipophilic) part that is water insoluble in either oil or water. Hydrophilic emulsifiers are employed in oil-in-water emulsions, while lipophilic or hydrophobic emulsifiers are used in water-in-oil emulsions.

Examples of emulsifying agents

Lecithin, soy lecithin, sodium phosphates, monoglycerides, diglycerides, sodium stearoyl lactylate.

Applications and Uses of Emulsions

Emulsions are utilised in a variety of applications. Emulsions are widely used in the pharmaceutical industry. A few of its applications are given below:

In the food industry, oil-in-water emulsions are employed. Vinaigrettes, for example, are prepared by suspending oil in vinegar or another acidic liquid.

1. Cutting fluid is a form of coolant or lubricant used in metalworking processes that is also an emulsion.

2. Mayonnaise, different sauces, and other emulsions of oil and water are stabilised by lecithin.

3. Margarine is an emulsion that is used in baking, cooking, and seasoning.

4. Pharmaceutical items such as creams, ointments, and balms are all emulsions. In pharmaceutics, emulsions are often utilised.

5. Emulsions are used in a lot of hair treatments and gels

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Some Solved Examples

Question 1: An emulsion is best described as:

A. A solution of two miscible liquids
B. A colloidal system of solid in liquid
C. A colloidal dispersion of one liquid in another immiscible liquid
D. A suspension of liquid in gas

Solution :

An emulsion is a colloidal system where one immiscible liquid is dispersed in another in the form of fine droplets.

Hence, the correct answer is option (C)

Question 2: Which of the following is an example of an oil-in-water (O/W) emulsion?

A. Butter
B. Milk
C. Cold cream
D. Margarine

Solution:

In milk, fat (oil) is dispersed in water → oil-in-water emulsion.

Hence, the correct answer is option (B)

Question 3: Which of the following substances acts as an emulsifying agent?

A. Sodium chloride
B. Soap
C. Sugar
D. Ethanol

Solution:

Soap contains both hydrophilic and hydrophobic parts, allowing it to stabilize emulsions.

Hence, the correct answer is option (B)

Question 4: The function of an emulsifying agent is to:

A. Increase surface tension
B. Decrease interfacial tension
C. Increase density of dispersion medium
D. Dissolve both liquids completely

Solution:

Emulsifying agents reduce interfacial tension between immiscible liquids, helping in emulsion formation.

Hence, the correct answer is option (B)

Question 5: Which theory explains emulsification by the formation of a protective film around droplets?

A. Surface tension theory
B. Viscosity theory
C. Film formation theory
D. Adsorption theory

Solution:
According to film formation theory, the emulsifying agent forms a thin film around droplets, preventing coalescence.

Hence, the correct answer is option (C)