What Is the Dispersed Phase? Understanding Concepts and Applications
To understand the dispersed phase, we need to understand what a colloid is. A colloid is a heterogeneous solution. In this solution, a dispersed phase is suspended in the dispersed medium. That is, the particles of the dispersed phase are present in the particles of the dispersed medium. A colloid solution does not possess a uniform mixture.
Water in starch or water in ink is an example of a heterogeneous mixture. Water is considered a dispersed medium in the above criteria, and starch or ink can be regarded as a dispersed phase. Two phases exist in this case. One step possesses finely differentiated particles suspended in a continuous medium. The stage with finely differentiated particles is called the dispersed phase. A dispersed medium consists of two media that do not mix. These two media can be different in properties altogether. Precisely, they can be a liquid, a solid or a gas. There are various everyday life examples of dispersed media. Milk, which we most probably use daily, is made up of oil drops dispersed in water. Shaving creams contain tiny airdrops of water dispersed in the air.
Difference Between Dispersed Phase and Dispersed Medium
The dispersed phase of dispersion is the discontinuous phase that distributes throughout the dispersion medium. It is one of the two stages of a colloid. The dispersion medium is the continuous phase of a colloid, and it distributes throughout the dispersion medium. The dispersed phase is known as the internal phase, whereas the dispersion medium is called the external phase. Examples of the dispersed phase include dust in the air, whereas that of dispersion medium includes water in milk.
Types of Dispersion Systems
There are two types of dispersion systems, Molecular Dispersions and Coarse Dispersions. Molecular dispersions are dedicated solutions to a solute phase in the solvent. The dispersed phase is homogeneously distributed in the dispersion medium. Examples of molecular dispersion are air (consisting of various gasses like nitrogen and oxygen), electrolytes, and alloys.
The second type of dispersion medium is of the coarse kind. These are heterogeneous dispersed systems. Fast sedimentation of the dispersed phase is observed owing to the coarse dispersions, mainly due to gravity.
Dispersed Phase: Classification and Types
Based on the type of dispersed phase, colloids can be classified into various types. These include sol, emulsion, foam, and aerosol. A colloidal suspension of solid particles in a liquid is called a sol, e.g., Ruby glass. An emulsion is a colloidal suspension of two drinks, e.g., milk. Foam is formed when gas particles get trapped in a liquid or solid, e.g., soap in water. Aerosols are small particles of liquid or solid dispersed in a gas, e.g., smoke, fog, mist, etc.
Depending upon the minute particles' nature of the dispersed phase, the colloids are mainly differentiated into three types:
Multimolecular colloids
Macromolecular Colloids
Associated Colloids
Multimolecular Colloids
When a substance gets dissolved in a dispersion medium, it gets separated into several smaller molecules of different sizes. Usually, their size varies from 1-1000nm. After the separation of the particles, the colloid constitutes several atoms and molecules known as multimolecular colloids.
Example: Hundreds of Sulfur molecules are held together by van der Waals force and form Sulfur Solution.
Macromolecular Colloids
Its size is relatively more. However, in a suitable solvent, these form solutions whose size may or may not remain in the colloidal range. This arrangement is popular as Macromolecular Colloids.
Example: Enzymes, cellulose, and proteins are naturally formed macromolecular colloids, but rubber and polythene are synthesized.
Associated Colloids
Basically, these are behaving like strong electrolytes. However, when a suitable condition like in higher concentration, they show the behavior of colloidal particles. Because of this nature, these are known as Associated Colloids and also famous as a micelle.
Examples: Soaps and detergents
How Does Dispersion Occur?
The agglomerated particles get separated from each other. A new line of interaction between the dispersion medium's inner surface and the outer surface of dispersed particles is created. This whole process is aided by molecular diffusion and convection. Through molecular diffusion phenomena, dispersion occurs through different concentrations of the media introduced throughout the bulk medium. The difference in engagement between dispersed material and the bulk medium creates a concentration gradient that drives the medium's dispersion.
This results in an equal dispersion of particles in the medium. In convection, variation in velocity between paths of flow in the bulk medium facilitates the equal distribution of dispersed material in the medium. Diffusion is the primary mechanism in dispersion, although it is driven by convection in some cases. In most cases, convection is what helps in accelerating the process of diffusion.
How Does Dispersion Occur in Prism?
To understand how dispersion occurs in a prism we need to first understand what is a prism. A prism is two rectangular bases and three rectangular surfaces in a solid figure. The angle of the prism is the angle between each surface. The surfaces are parallel and equal. Now let's begin with the experiment.
We need a constant beam of light, a prism, and a white plain wall to produce seven different colors with a single white light. First, place the project components near the window. Make sure that the sunlight should fall on the prism in such a way that it should cover one side of the prism and then on the wall.
Observation
You can observe that a single beam of light from the sun is now separated into seven different colors. This process of separating a single light into various wavelengths is known as dispersion of light.
The colors that you see are called VIBGYOR. VIBGYOR stands for letter V as Violet, the letter I as indigo, letter B as blue, letter G as green, letter Y as yellow, letter O as Orange, and letter R as red. The color pattern which we get after throwing a single beam of light on a prism or any other object is called a spectrum. Another example of the spectrum is the rainbow but you cannot see all the seven colors because the colors overlap each other.
What is a Dispersion System and How Does it Work?
The dispersion system has a two-sided system that is made up of microscopic particles along with a medium that helps them to be suspended. The dispersion system works on a basic principle that it separates the collection of particles from each other. Light can be a common example of dispersion. The second commonly used example is a rainbow. Let us know how this works. The speed of the light ray results in light dispersion. Similarly, the dispersion of a rainbow is a spatial disconnection of a single white light into many different lights.
Dispersion Medium
Foam
Foam is a colloidal system. The particles are gas bubbles whereas the medium is a liquid. Foam can be easily classified as something which is light in weight or rigid form. Long-lasting foams are made from liquid foams, purposely made for heavy usage. For example - Fire fighting. Stabilizers are used to prevent the coalescence of the bubbles. Proteins are well known as a stabilizer as they are edible in nature.
Aerosol
It is described as the chemistry of solid, liquid, and gas particles. Fog is a natural aerosol.
Solid suspension
A solid suspension is a mixture in which the solute particles do not dissolve. The mixture of chalk water is a common example of a solid suspension.
Gels
Gels are solid in the medium. Gelation is the process in which gel is foamed.
Colloidal Suspension
The particle size of a colloidal suspension is large. Muddy water is a good example of colloidal suspension.
Emulsion
The emulsion is a mixture of more than one liquid or moire that cannot be mixed. Emulsion belongs to the general class. A golden example of an emulsion is water and oil. If stirred it will mix for a while but soon it will be separated.
Solid Foam
Dry wood is a classic example of solid foam. they are made out of a specific framework. Commonly used in yoga mats.
What is a Colloid?
A colloid is a mixture of only one particular substance which is evenly distributed. There can be only two different states. Diameters range between 5 and 200 nanometres. Milk is a classic example of colloid in liquid whereas shaving cream is a colloid of gas inside the liquid.
What is a Solution in Chemistry?
The solution is a similar mixture of two or more substances in equal amounts. However, Solutions of gas and solid are possible. A commonly used example is air. Air is a mixture of several gases but the major gases of air are oxygen and nitrogen. The solution consists of two substances, Solvent, and the substance mixed with it is called the solute.
Solvent
The solvent is basically a liquid in which various materials can be mixed to make a solution. For better understanding, water is a solvent.
Solute
The solute can be a substance or a material that has been dissolved in a solvent to create a mixture. A common example is a saltwater. In this case, salt is a solute mixed with water, water is solvent to produce a mixture called a solution.
Conclusion
We have covered all aspects of the Dispersed Phase and its classification. This clear picture will help you in learning the topic well.
FAQs on Dispersed Phase in Chemistry: Definition, Types & Examples
1. What is the dispersed phase in the context of a colloidal solution?
The dispersed phase is the substance that is distributed in the form of very fine, insoluble particles throughout another substance. It is analogous to the solute in a true solution, but its particles are larger (typically 1-1000 nanometres) and remain suspended rather than fully dissolved. For example, in fog, tiny water droplets are the dispersed phase.
2. What is the main difference between a dispersed phase and a dispersion medium?
The primary difference lies in their roles within a colloid. The dispersed phase is the component present in a smaller proportion, consisting of particles that are scattered. The dispersion medium is the component present in a larger proportion, acting as the continuous medium in which the dispersed phase particles are suspended. Think of it as the 'stage' (dispersion medium) where the 'actors' (dispersed phase) are present.
3. How are the dispersed phase and dispersion medium different from the solute and solvent in a true solution?
While analogous, they are fundamentally different. In a true solution, the solute dissolves to form a homogeneous mixture with the solvent, and its particles are of ionic or molecular size (<1 nm). In a colloid, the dispersed phase consists of larger particles (1-1000 nm) that do not dissolve but remain suspended in the dispersion medium, forming a heterogeneous system where a distinct interface exists between the two phases.
4. What are some common examples of colloids, highlighting their dispersed phase and dispersion medium?
Here are a few examples of colloids from daily life, illustrating the different types of dispersed phases and dispersion mediums:
- Smoke: Solid carbon particles (dispersed phase) are suspended in air (dispersion medium).
- Milk: Liquid fat globules (dispersed phase) are emulsified in water (dispersion medium).
- Fog/Mist: Liquid water droplets (dispersed phase) are scattered in air (dispersion medium).
- Paint: Solid pigment particles (dispersed phase) are suspended in a liquid base (dispersion medium).
- Cheese: Liquid fat (dispersed phase) is trapped within a solid protein matrix (dispersion medium).
5. Can a gas act as a dispersed phase in another gas to form a colloidal solution? Why or why not?
No, a gas cannot act as a dispersed phase in another gas to form a colloid. This is because all gases are completely miscible with each other. When two or more gases are mixed, they form a homogeneous solution, not a heterogeneous colloidal system. A colloid requires a distinct interface between the dispersed phase and the dispersion medium, which is not possible with a gas-in-gas mixture.
6. How does the particle size of the dispersed phase affect the properties and classification of a mixture?
The particle size of the dispersed phase is a critical factor that determines whether a mixture is a true solution, a colloid, or a suspension.
- True Solution: Particles are <1 nm. They do not scatter light and cannot be separated by filtration.
- Colloid: Particles are between 1-1000 nm. They are large enough to scatter light (Tyndall effect) but small enough to not settle down due to gravity.
- Suspension: Particles are >1000 nm. They are visible, scatter light, and are heavy enough to settle down over time.
7. How are different types of colloids classified based on the physical state of the dispersed phase and dispersion medium?
Colloids are classified into eight types based on the physical state (solid, liquid, gas) of the two phases:
- Solid in Solid (Solid Sol): Gemstones, coloured glass.
- Solid in Liquid (Sol): Paint, cell fluids.
- Solid in Gas (Aerosol): Smoke, dust.
- Liquid in Solid (Gel): Cheese, butter, jellies.
- Liquid in Liquid (Emulsion): Milk, hair cream.
- Liquid in Gas (Aerosol): Fog, mist, clouds.
- Gas in Solid (Solid Foam): Pumice stone, foam rubber.
- Gas in Liquid (Foam): Whipped cream, soap lather.
8. In an emulsion, what determines which liquid is the dispersed phase and which is the dispersion medium?
In an emulsion, which consists of two immiscible liquids, the component present in a smaller amount typically forms the dispersed phase (droplets), while the component in a larger amount forms the dispersion medium (the continuous phase). For example, in an oil-in-water (O/W) emulsion like milk, oil is the dispersed phase, and water is the dispersion medium. The type of emulsion can be identified by the dilution test; an emulsion can be diluted with its dispersion medium.
