Difference Between Dispersed Phase and Dispersion Medium

Main Difference – Dispersed Phase vs Dispersion Medium

A dispersion is a system in which particles of one phase are dispersed throughout a medium that is in a different phase. Therefore a dispersion is a two-phased system. It is composed of a dispersion medium and a dispersed phase. Dispersion medium is a continuous medium in which the dispersed phase is distributed throughout. Dispersed phase is the phase that is composed of particles that are distributed through another phase. The main difference between dispersed phase and dispersed medium is that dispersed phase is a discontinuous phase whereas dispersion medium is a continuous phase.

Key Areas Covered

1. What is Dispersed Phase
      – Definition, Different Types
2. What is Dispersion Medium
      – Definition, Explanation
3. What is the Difference Between Dispersed Phase and Dispersion Medium
      – Comparison of Key Differences

Key Terms: Associated Colloids, Dispersed Phase, Dispersion, Dispersion Medium, Foam, Macromolecular Colloids, Multimolecular Colloids

What is a Dispersed Phase

Dispersed phase is one of the two phases in a colloid. The dispersed phase is a discontinuous phase that is distributed throughout the dispersion medium. The dispersed phase is composed of particles that have diameters around 1-100 nm.

There can be three types of particles in the dispersed phase. According to these particles, the colloids can be categorized into three groups as,

1. Multimolecular colloids
2. Macromolecular colloids
3. Associated colloids (miscells)
   

   Figure 1: Synthetic Detergents are associated Colloids

The dispersed phase of multimolecular colloids has low molecular weight particles which can combine to form large particles that have their dimensions in colloidal range. Sulfur solution is a good example. Here, a large number of S₈ units are present in one colloidal particle. The dispersed phase of macromolecular colloids is composed of heavy molecular weight particles of the individual particles that are in colloidal range. Starch solution is a good example of this. Here, glucose molecules are suspended in water. Associated colloids are composed of a dispersed phase which has particles formed from the aggregation of smaller particles. Soap and synthetic detergents are good examples of associated colloids.

What is Dispersion Medium

Dispersion medium is the continuous phase of a colloid. It is the phase in which the dispersed phase is distributed. It can be in any state of matter: solid, liquid or gas. It is also called the external phase because the dispersed phase is inside the dispersion medium.

Figure 2: Milk is Composed of Oil Drops Dispersed in Water. Water is the Dispersion Medium.

Let us consider some examples. Milk is a colloidal dispersion. It is composed of oil drops in water. Thus, the water is the dispersion medium. Fog has water droplets dispersed throughout the air. Therefore, air is the dispersion medium. In solid foam sponge, air bubbles are dispersed throughout the foam material. There, the foam material is the dispersion medium.

Difference Between Dispersed Phase and Dispersion Medium

Definition

Dispersed Phase: Dispersed phase is one of the two phases in a colloid.

Dispersion Medium: Dispersion medium is the continuous phase of a colloid.

Continuity

Dispersed Phase: Dispersed phase is discontinuous.

Dispersion Medium: Dispersion medium is continuous.

Other Names

Dispersed Phase: Dispersed phase is known as internal phase.

Dispersion Medium: Dispersion medium is known as external phase.

Common Examples

Dispersed Phase: Dust particles (in air) belong to dispersed phase.

Dispersion Medium: Water in milk is dispersion medium.

Conclusion

Dispersed phase and dispersion medium are the two main components of a colloid. Dispersed phase is distributed throughout the dispersion medium. The main difference between dispersed phase and dispersed medium is that dispersed phase is a discontinuous phase whereas dispersion medium is a continuous phase.

References:

1. “Dispersion (Chemistry).” Wikipedia, Wikimedia Foundation, 8 Sept. 2017, Available here.
2. “Dispersed phase and dispersion medium- Classification and types.” Chemistry, Byjus Classes, 22 Sept. 2017, Available here.
3. “Dispersed media.” Wikipedia, Wikimedia Foundation, 8 Sept. 2017, Available here.

Image Courtesy:

1. “Diskflaskor” By Nordelch – Own work (CC BY 3.0) via Commons Wikimedia
2. “Glass Of Milk” (Public Domain) via PublicDomainPictures.net