Dispersed Phase
Definition and meaning of Dispersed Phase in chemistry.
Dispersed phase is the substance present as finely divided particles distributed throughout a continuous surrounding substance (the dispersion medium) in a colloid, emulsion, or suspension.
In more detail
The dispersed phase particles are broken up into small units, ranging from about 1 to 1000 nanometers for true colloids (though the same term is used loosely for coarser suspensions and emulsions), and are held apart from one another by the dispersion medium rather than settling out or coalescing. Because the particles are small, they scatter light (the Tyndall effect) and their stability depends on factors like surface charge, adsorbed layers, and Brownian motion preventing aggregation. Either phase can be a solid, liquid, or gas, giving rise to different colloid types such as sols, emulsions, foams, and aerosols.
Key facts
| Field | Physical Chemistry |
|---|---|
| Typical particle size | ~1-1000 nm (colloidal range) |
| Also called | internal phase or discontinuous phase |
| Counterpart term | dispersion medium (continuous phase) |
In milk, tiny fat globules (the dispersed phase) are spread throughout the watery portion (the dispersion medium), forming an oil-in-water emulsion.
Frequently asked questions
What is the difference between the dispersed phase and the dispersion medium?
The dispersed phase is the substance broken into small particles, while the dispersion medium is the continuous substance that surrounds and supports those particles.
Can the dispersed phase be a gas?
Yes. In a foam, gas bubbles form the dispersed phase within a liquid or solid dispersion medium, as seen in whipped cream or foam rubber.