What is an emulsion and how does it work?

An emulsion is a type of colloid consisting of a mixture of two or more liquids that are normally unmixable due to liquid-liquid phase separation. In these systems, one liquid forms a dispersed phase within a second continuous liquid phase. Common examples include vinaigrettes, homogenized milk, and specific formulations used in manufacturing and polymer chemistry.

What we know

• An emulsion is defined as a mixture of two or more normally immiscible liquids resulting from liquid-liquid phase separation. [1, 2]
• Emulsions fall under the broader class of two-phase systems of matter known as colloids. [1, 2]
• Two liquids can form different types of emulsions, such as oil-in-water or water-in-oil systems, as well as multiple emulsions. [2]
• Emulsification is the process of dispersing immiscible liquids together through the use of an emulsifier like lecithin. [2]

Still open

• The terms colloid and emulsion are sometimes used interchangeably, though emulsion more narrowly refers specifically to systems where both the dispersed and continuous phases are liquids.

Where to go next

• how it workedHow does emulsion polymerization create synthetic polymers?
• the bigger pictureWhat are colloids in physical chemistry?
• a case in pointHow do photographic film emulsions capture images?
• compared withHow do oil-based and water-based paints differ?
• what followedWhat applications do nanoemulsions have in technology?
• an unexpected connectionHow are photographic films related to liquid mixtures?Photographic emulsions use the term emulsion to describe solid silver halide colloidal particles dispersed inside a gelatin matrix rather than two immiscible liquids.

Sources

• [1]emulsion (Wikidata Q187634) · CC0 1.0
• [2]Emulsion · CC BY-SA 4.0
• [3]Emulsion polymerization · CC BY-SA 4.0
• [4]Paint · CC BY-SA 4.0
• [5]Fluorine · CC BY-SA 4.0