An emulsion is defined as which of the following?

• A. A mixture of two or more immiscible liquids in which one liquid is dispersed in the other
• B. A homogeneous solution of solutes in a solvent
• C. A suspension in which particles settle quickly
• D. A pure liquid with no solutes

Answer: (A)

An emulsion is a system where two liquids that do not mix form droplets of one liquid dispersed in the other. The dispersed droplets create a heterogeneous mixture with a continuous phase and a dispersed phase. This distinguishes it from a homogeneous solution, which has a uniform composition throughout, and from a suspension, where solid particles are dispersed and tend to settle. It also isn’t a pure liquid, since a second immiscible liquid is present as droplets. Emulsions are seen in foods and cosmetics—oil droplets in water or water droplets in oil—often stabilized by emulsifiers that reduce interfacial tension and help keep droplets from coalescing.