JEE Exam » JEE Study Material » Chemistry » Theories of Emulsification

Theories of Emulsification

There are three theories of emulsification: surface tension theory, oriented wedge theory, and interfacial film theory. More than one theory can be applied to the same emulsion system.

An emulsion is a dispersion in which the dispersed phase is made of minute globules of a liquid that are scattered across an immiscible medium. It is the dispersion medium that is the exterior phase, not the dispersed phase, that is the interior phase.

In order to form an emulsion, the emulsifying agent must be present. Liquid emulsions can be used either orally, topically, or parenterally, depending on the contents and the intended application. This article will be your ultimate guide to theories of emulsification as well as theories of emulsification questions and answers. 

Emulsifying Agents

In order to keep emulsions stable, emulsifying agents are added. The following is a list of emulsifier characteristics:

  • They are compounds that have both a hydrophilic (polar) and hydrophobic end (non-polar)
  • They can be dissolved in water as well as oil
  • Emulsifiers produce a layer between both the dispersed phase and the medium, preventing the dispersed phase particles from forming bigger particles and separating
  • They can be cationic, anionic, or even non-polar, depending on the application
  • Water and oil aren’t the only factors to consider when it comes to the composition of an emulsion
  • Solubility differences between oil and the emulsifier can cause water to act as the dispersant medium, and oil to act as the dispersed phase
  • While this may be true, it is more likely that oil will be the dispersion medium and water the dispersed phase when the emulsifier is water-soluble in oil
  • Proteins, gums, soaps, and other typical emulsifiers are utilised in o/w emulsions

Cellulose, DATEM, egg yolk, mustard, sodium phosphates, mono- and diglycerides, sodium phosphates, soy lecithin, etc. are examples of emulsifiers.

The theories three theories of emulsification are:

1. Surface Tension Theory of Emulsification

  • This theory states that surface-active agents reduce the interfacial tension between two immiscible liquids, reducing the repellent force between both the liquids and decreasing the attraction of each liquid for its own molecules
  • Surface active agents (surfactants) are used
  • Surfactants help break up big globules into tiny ones, which, therefore, have a lower inclination to reconnect or agglomerate, allowing them to disperse more easily

2. Oriented Wedge Theory of Emulsification

  • Soap is a common example of a diluted emulsion in which two to four per cent oil is emulsified in water without the need of an emulsifying agent
  • This means that if soap is used, ninety-nine times the volume of water can be absorbed by oil
  • The hydrocarbon radical points toward oil and Na+ points toward water per the oriented wedge theory of soap molecules in an oil-water interface
  • Non-polar or “oily” ends turn toward oil, while “polar” or “liquid” ends turn towards polar liquid
  • According to the oriented wedge theory of emulsions, oil in water emulsions (or the usual type) form when the nonpolar end of the emulsifying agent’s molecule shrinks, while water droplets form when the polar end shrinks
  • In order for fluids and solids to have a distinct surface layer from their internal mass because the stray field of the molecule is asymmetrical, the axes of the fields must be oriented differently than they are in a pure substance where all molecules are aligned in a random manner

3. Interfacial Film Theory of Emulsification

  • A thin coating adsorbed to the surface of the internal phase droplets surrounds the droplets of this theory’s emulsifying agent, preventing contact and the coalescence of the dispersion phase
  • There is a direct correlation between water-soluble compounds and the o/w and the w/o emulsion

Theories of Emulsification: Importance

Several theories are relevant in a single emulsion system. For example, reducing the interfacial tension is critical during the earliest stages of emulsion formation. However, the development of a protective molecular wedge or emulsifier layer is essential for long-term stability.


To sum it up, in the surface tension approach, emulsification is described as a process where, between two phases, the interfacial tension is reduced. In the interfacial tension theory, the emulsifying agent generates a film over one phase that further leads to the formation of globules. To keep them suspended in the medium, these chemicals have a tendency to resist one another. Oil in water emulsions (or the normal variety) occur when the nonpolar end of the emulsifying agent’s molecule shrinks. In contrast, water droplets form when the polar end shrinks, according to the oriented wedge hypothesis of emulsions.


Frequently Asked Questions

Get answers to the most common queries related to the JEE Examination Preparation.

What are emulsions? Explain with some examples from everyday life?

Answer: When two liquids are mixed together, the result is an emulsion, which is a type of colloid. In an emulsion, ...Read full

What are the types of emulsions?

Answer: There are two types of emulsions: Water-in-oil: ...Read full

What is the oriented wedge theory of emulsification?

Answer: Based on the solubility of the emulsifying agents in a particular liquid, this hypothesis assumes that monom...Read full

Are theories of emulsification mutually exclusive?

Answer: More than one theory can be applied to the same emulsion system. Emulsion stability is dependent on both the...Read full

How can we test the oriented wedge theory of emulsification?

Answer: The use of both larger polar and larger non-polar end molecules in the emulsifying agents is required to ver...Read full