What is an emulsion?

We explain what a chemical emulsion is, what its phases are, how it is classified and what examples we find in everyday life.

1. What is an emulsion?

It is understood by chemical emulsion or simply emulsion at the more or less homogeneous junction of two immiscible liquids , that is, they do not mix completely with each other. Emulsions consist of the dispersion of one liquid or phase in the other.

They form what is ordinarily known as a colloid. Although these two terms are used interchangeably, emulsions differ from other colloids because they are always composed of liquid phases .

These two phases that make up an emulsion are always two different:

• Continuous phase . That which is predominant to the other, that is, the one within which the dispersed phase is dispersed.
• Phase dispersed . That which is a minority in front of the other, that is, that is dispersed within the other.

Due to different chemical and physical phenomena, emulsions always tend to be white, unless they are diluted emulsions (then tending to blue) or concentrating (tending to yellow). Both are distinguished from the concentration gradient of one phase in the other.

Many times an emulsion occurs due to the presence of emulsifying substances, that is, particles that facilitate or favor the formation of emulsions between substances that would ordinarily be much more complicated to do so.

In the same way, an emulsifier or emulsifier is a substance that stabilizes this type of mixtures preventing its phases from dispersing, acting as a binder material.

Emulsions can be of different types:

• Direct emulsions . Those that combine a lipophilic dispersed phase (attracted by fats) and a continuous hydrophilic phase (attracted by water ).
• Inverse emulsions . Those that combine a hydrophilic dispersed phase and a lipophilic continuous phase, that is, the opposite of the direct ones.
• Multiple emulsions . Those that have an inverse emulsion as dispersed phase, and an aqueous liquid as a continuous phase.

2. Examples of chemical emulsions

Some common and everyday emulsions are:

• Milk (water and animal fat emulsion)
• Mayonnaise (water and oil emulsion)
• The vinaigrette sauce (oil and vinegar emulsion)
• The oil (emulsified oil)
• Ice cream (milk and almost frozen water emulsion)
• Butter (milk and oil emulsion)
• Bitumen or asphalt (hydrocarbon emulsion)