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How will you distinguish a Colloid from a Solution?

  • Last Updated : 13 Oct, 2021

A colloid is a mixture in which one material is suspended throughout another substance and contains scattered insoluble particles. The whole mixture is referred to as a colloidal solution. A colloid has a dispersed phase (suspended particles) and a continuous phase, unlike a solution, which has only one phase with the solute and solvent (the medium of suspension). To be classified as a colloid, the mixture must either not settle or settle very slowly.

Types of Colloids

The phase of the dispersed substance and the phase in which it is disseminated are two typical methods of characterizing colloids. Sol, emulsion, foam, and aerosol are examples of colloids.

  • A colloidal dispersion of solid particles in a liquid is known as a sol.
  • A blend of two or more liquids is known as an emulsion.
  • When a large number of gas particles are trapped in a liquid or solid, foam is created.
  • Aerosols are made up of small liquid or solid particles suspended in a gas.

The colloidal system is known as a hydrocolloid when the dispersion medium is water. Depending on how much water is available, the particles in the dispersed phase might go through several stages. A hydrocolloid is created when Jello powder is combined with water. Medical dressings are a popular application for hydrocolloids.

Dispersed Material

Dispersed in Gas

Dispersed in Liquid

Dispersed in Gas

Gas (Bubbles)

Not possible

Foams: Whipped CreamSolid foams: Plaster

Liquid (Droplets)

Mist, Clouds

Emulsions: Milk, BloodButter

Solid (Grains)

Dust, Industrial Smoke

Sols and Gels: Muddy water, Starch SolutionSolid Sol: Pearl

Physical Properties of Colloids:

  1. Heterogeneous Nature: Colloidal solutions are heterogeneous in nature, with two distinct phases: dispersion and dispersion medium.
  2. Nature of the solutions: The solutions are extremely stable. They are constantly in motion and never settle at the bottom of a container.
  3. Filterability: Colloidal particles flow through standard filter sheets with ease.

Colligative properties of Colloids: 

  1. Observed values of colligative qualities such as relative decrease vapour pressure, elevation in boiling point, depression in freezing point, and osmotic pressure are smaller than expected due to the creation of linked molecules.
  2. The number of particles in a particular solution will be quite small.

Mechanical properties of Colloids: 

  1. Diffusion: Sol particles diffuse from a high-concentration area to a low-concentration area. They do, however, diffuse at a slower rate due to their larger size.
  2. Sedimentation: Under the action of gravity, colloidal particles settle down at a very slow rate. The molecular mass of macromolecules is determined using this phenomenon.

Similarities between Colloid and Solutions: True solutions are liquid-phase combinations in which the solute and solvents are thoroughly combined. Colloidal solutions are mixtures in which the solute (small particles or colloids) is evenly distributed throughout the solvent (liquid phase).

Tyndall Effect

Using the Tindall effect, we can tell the difference between colloids and real solutions. A colloid is a solution that scatters a ray of light travelling through it and makes its path visible. A real solution is one that does not scatter a beam of light travelling through it and does not make its route visible.

The Tyndall effect is a phenomena in which light beams are scattered by the particles in a colloid. All colloidal fluids and certain very fine suspensions exhibit this effect. As a result, it may be used to identify whether or not a solution is a colloid. The density of colloidal particles, as well as the frequency of incident light, determine the intensity of scattered light.

Colloidal particles in the solution prevent a light beam from passing entirely through it when it travels through a colloid. When light collides with colloidal particles, it scatters (it deviates from its normal trajectory, which is a straight line). The path of the light beam is visible as a result of this dispersion. When compared to red light, blue light is scattered to a higher amount. This is due to the fact that blue light has a shorter wavelength than red light. This is why the smoke emitted by motorcycles might appear blue at times.

Tindall Effect

Distinguishing a colloid from a solution

  1. True solutions are homogeneous, whereas colloidal solutions are heterogeneous in nature.
  2. True solution solvent particle sizes are smaller than 1 nm, but colloidal solution solvent particle sizes range from 1 nm to 1000 nm.
  3. Even under an ultramicroscope, true solution particles are invisible, however colloidal solution particles are visible.
  4. The Tyndall effect does not appear in a real solution, but it occurs in a colloidal solution.

Emulsions: Emulsions are a type of colloids that includes butter and mayonnaise. A colloidal dispersion of a liquid in either a liquid or a solid is known as an emulsion. An emulsifying agent is required for a stable emulsion. Oil and vinegar are used to make mayonnaise. Because oil is nonpolar and vinegar is a polar aqueous solution, the two do not mix and separate fast into layers. The inclusion of egg yolk, on the other hand, stabilizes the mixture and prevents it from separating. Both the polar vinegar and the nonpolar oil can interact with the egg yolk. The emulsifying agent is the yolk of an egg.

Sample Questions 

Question 1: What are the types of colloids?

Answer:

The phase of the dispersed substance and the phase in which it is disseminated are two typical methods of characterizing colloids. Sol, emulsion, foam, and aerosol are examples of colloids.

  1. A colloidal dispersion of solid particles in a liquid is known as sol.
  2. A blend of two or more liquids is known as an emulsion.
  3. When a large number of gas particles are trapped in a liquid or solid, foam is created.
  4. Aerosols are made up of small liquid or solid particles suspended in a gas.

Question 2: What type of mixture is a smoke flare?

Answer:

Assume you’re on a yacht sailing. The engine fails unexpectedly, leaving you adrift in the midst of the ocean. You call the Coast Guard on your radio, but your GPS isn’t working, so you can’t tell them a precise location. You have a smoke flare, which you use to clear the area. The dense colored smoke alerts the Coast Guard to your location, allowing them to rescue you. When you use the flare, you’re using a colloid, which is a form of mixture.

Question 3: Which of the following will show the Tyndall effect and why? 

Salt solution, milk, copper sulphate solution and starch solution.

Answer:

The Tyndall effect can be seen in milk and starch solutions.

The Tyndall effect describes how the particles in a colloid scatter the light rays that are focused at them. This effect can be seen in all colloidal solutions including certain very tiny suspensions. As a result, it can be used to determine if a given solution is a colloid. The intensity of scattered light is determined by the density of colloidal particles as well as the incident light frequency.

Question 4: Give some examples of the Tyndall effect.

Answer:

Milk is a colloid that consists of fat and protein globules. When a beam of light is aimed towards a glass of milk, the light is dispersed. The Tyndall effect is perfectly described in this way. When a torch is turned on in a foggy environment, the direction of the light becomes apparent. The dispersion of light in this scenario is due to the water droplets in the fog.

Question 5: What is Tyndall Effect?

Answer:

The Tindall effect is a phenomena in which light beams are scattered by the particles in a colloid. All colloidal fluids and certain very fine suspensions exhibit this effect. As a result, it may be used to identify whether or not a solution is a colloid. The density of colloidal particles, as well as the frequency of incident light, determine the intensity of scattered light.


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