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Tyndall Effect

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  • Last Updated : 21 Jul, 2021

Mixtures are made up of more than one pure form of matter. A non-chemical combination of two or more substances is referred to as a mixture (elements or compounds).

  • A mixture’s constituents retain their original properties.
  • The separation of components is straightforward.
  • Each component’s proportion varies.

There are two types of Mixtures, Homogeneous Mixtures and Heterogeneous mixtures.

Homogeneous Mixtures:

A homogeneous mixture is one in which the composition of its constituents is uniform throughout its mass. It lacks visible boundaries that separate the various components. As an example, consider a sugar solution or a salt solution.

Heterogeneous Mixtures:

Heterogeneous mixtures do not have a uniform composition throughout their mass and have visible separation boundaries between various components. As an example, consider a sand and water mixture.

What is a Solution?

A solution is a homogeneous mixture of two or more components with particle sizes less than one nanometer. In your daily life, you come across various types of solutions. Sugar in water and salt in water solutions, as well as soda water, are common examples of solutions. All of the components appear as a single phase in a solution. There is particle homogeneity, which means that the particles are evenly distributed. This is why a whole bottle of soft drink tastes the same.

Properties of Solution:

  • A solution is a homogeneous mixture of substances.
  • A solution’s particles are less than 1 nm (10-9 meter) in diameter. So, they are invisible to the naked eye.
  • They do not scatter a light beam passing through the solution due to their very small particle size. As a result, the light path is not visible in a solution.
  • The filtration process cannot separate the solute particles from the mixture. When left undisturbed, the solute particles do not settle, indicating that the solution is stable.

What is a Suspension?

A suspension is a heterogeneous mixture in which solid particles are distributed throughout the liquid but do not dissolve in it. A suspension is defined as a homogeneous mixture of particles with diameters greater than 1000 nm that can be seen with the naked eye. All of the components are completely mixed in this type of mixture, and all the particles can be seen under a microscope. A suspension is a heterogeneous mixture containing solid particles large enough to sediment.

If we put mud in a glass of water, it will form a heterogeneous mixture. The components of these mixtures are easily identified. After some time, we will notice that mud particles settle down due to gravity. Particles in suspension are larger than those in solution.

Properties of Suspension:

  • A suspension is a mixture of different substances.
  • Solute particles in a suspension are quite large in size. It has a diameter greater than 100 mm.
  • Suspension particles are easily visible.
  • Suspension particles do not pass through filter paper. Filtration can thus separate a suspension.
  • The suspension is shaky. After some time, the particles in a suspension settle down.
  • Because of its large particle size, a suspension scatters a light beam passing through it.

What is Colloid?

Colloids are also referred to as colloidal solutions or colloidal systems. A colloid is a substance that exists between a solution and a suspension. It contains particles ranging in size from 2 to 1000 nanometers. A colloid is visible with the naked eye. The Tyndall effect can be used to differentiate between colloids and solutions. The scattering of light (light beam) through a colloidal solution is referred to as the Tyndall effect. The particles are referred to as colloidal particles, and the resulting mixture is referred to as colloidal dispersion. A colloidal dispersion is formed when liquids, solids, and gases come together.

Properties of Colloid:

  • A colloid is a mixed substance that is heterogeneous in nature.
  • A colloid’s particles are too small to be seen individually with the naked eye.
  • Colloids are large enough to scatter a light beam passing through them and reveal their path.
  • They do not settle down when left alone, indicating that a colloid is quite stable.

The different types of colloidal solution are:

  • Aerosols: Aerosols are solids or liquids that have been mixed with gas. As an example, consider fog (liquid in gas)
  • Sols: Sols are solids that have been mixed with liquids. For example, paint.
  • Emulsion: Emulsions are liquids that have been mixed with liquids. As an example, consider oil and water.
  • Gel: A liquid that has solidified. Fruit jelly is an example of a gel.

Tyndall Effect

The scattering of light (light beam) through a colloidal solution is referred to as the Tyndall effect. When particles in a colloid scatter light beams directed at them, this is known as the Tyndall effect. This effect can be seen in all colloidal solutions and some very fine suspensions. As a result, it can be used to determine whether a given solution is a colloid. The intensity of scattered light is affected by the density of colloidal particles as well as the frequency of incident light.

When a light beam passes through a colloid, the colloidal particles in the solution prevent the beam from completely passing through. Light is scattered when it collides with colloidal particles (it deviates from its normal trajectory, which is a straight line). This scattering reveals the path of the light beam, as shown below.

The Irish physicist John Tyndall discovered (and is named after) the Tyndall effect. The particles that cause the Tyndall effect can have diameters ranging from 40 to 900 nanometers (1 nano meter = 10-9 meter). In comparison, the visible light spectrum has wavelengths ranging from 400 to 750 nanometers.

Tyndall EffectSolution ColloidSuspension
Do not scatter lightScatter light (Tyndall effect)May either scatter light or be opaque

Examples of the Tyndall Effect:

  • The Tyndall effect can be demonstrated by shining a flashlight beam into a glass of milk. You might want to use skim milk or dilute the milk with a little water to see how the colloid particles affect the light beam.
  • The blue color of smoke from motorcycles or two-stroke engines is an example of how the Tyndall effect scatters blue light.
  • The Tyndall effect is responsible for the visible beam of headlights in fog. The light is scattered by the water droplets, making the headlight beams visible.
  • In commercial and laboratory settings, the Tyndall effect is used to determine the particle size of aerosols.
  • The Tyndall effect is visible in opalescent glass. Although the glass appears blue, the light shining through it appears orange.
  • The blue eye color is caused by Tyndall scattering through the translucent layer over the iris of the eye.

Sample Questions

Question 1: What exactly are colloids? Can you give an example?

Answer: 

Colloids are also referred to as colloidal solutions or colloidal systems. A colloid is a substance that exists between a solution and a suspension. It contains particles ranging in size from 2 to 1000 nanometers. A colloid is visible to the naked eye.

Question 2: What exactly do you mean by the Tyndall effect?

Answer: 

The scattering of light (light beam) through a colloidal solution is defined as the Tyndall effect. The colloidal solution is identified using the Tyndall effect.

Question 3: What are the properties of colloids?

Answer: 

The properties of a colloid are as follows:

  • A colloid is a mixed substance that is heterogeneous in nature.
  • A colloid’s particles are too small to be seen individually with the naked eye.
  • Colloids are large enough to scatter a light beam passing through them and reveal their path.
  • They do not settle down when left alone, indicating that a colloid is quite stable.

Question 4: What exactly are sol. Can you give an example?

Answer: 

A sol is a colloid composed of very small solid particles suspended in a continuous liquid medium. Sols are fairly stable and exhibit the Tyndall effect. Blood is one example.

Question 5: What exactly is a Tyndall cone?

Answer: 

When light passes through a colloidal solution, the path of light appears to be a bright cone due to Tyndall scattering. This is due to the fact that colloidal particles scatter light in all directions. Tyndall cone is the name given to this.


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