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Colloidal Solution- Definition, Properties, Examples, Particle size

Colloidal Solution

Colloids (also known as colloidal solutions or colloidal systems) are mixes in which insoluble particles of one substance are suspended in another substance at a microscopic level. In a colloid, the size of the suspended particles can range from 1 to 1000 nanometres (10-9 metres). The suspended particles in a combination must not settle in order to be categorised as a colloid (in the manner that the particles of suspensions settle at the bottom of the container if left undisturbed). The Tyndall Effect is a phenomena in which light beams incident on colloids are scattered due to interactions between the light and the colloidal particles. Colloidal particles are the tiniest particles. Colloids, on the other hand, are essentially solutions with solute particle sizes ranging from 1nm to 1000nm. Colloids are naturally diverse.
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Colloidal Solution: Definition

Colloids are defined as a mixture in which one of the components is broken down into very small particles that are spread throughout a second material. A colloid is a combination in which one ingredient is suspended throughout another substance by microscopically distributed insoluble particles. The particles must be spread in a liquid, according to some definitions. Interface and colloid science is concerned with colloidal suspensions. Italian chemist Francesco Selmi first developed this topic of study in 1845, while Scottish scientist Thomas Graham has been researching it since 1861.

Colloidal Solution: Examples

Colloids are not all kinds of mixes. Colloids are mixtures in which the suspended particles do not settle at the button and are equally disseminated in another substance. The following are some examples of colloidal solutions:

  • Blood
  • Whipped cream
  • Paints
  • Flame retardants
  • Butter
  • Cheese
  • Perfume
  • Gelatin
  • Dirty water
  • Starch solution

and many other substances.


Colloidal Solution: Properties

The colloidal solution exhibit a wide range of properties which are classified into three broad types discussed below:


  • When a powerful beam of light is sent through a colloidal sol, the light scattering by the colloidal particles produces a visible cone. The Faraday–Tyndall effect is what causes this.
  • The electron microscope, which can provide images of actual particles, even those reaching molecular dimensions, is now routinely used to examine colloidal particle size, shape, and structure. The electron microscope’s success can be attributed to its great resolving power, which is measured in terms of ‘d,’ the lowest distance between two objects that allows them to be distinguished. The smaller the wavelength of the radiation employed, the lower the value of ‘d’ and the higher the resolving power.
  • The optical microscope’s radiation source is visible light, which can only discern two particles at a time of roughly 20 nanoseconds. The electron microscope’s radiation source is a stream of high-energy electrons with wavelengths in the 0.01 nm range.
  • The above-mentioned Faraday-Tyndall Effect is used to explain the light scattering property of colloidal solution particles. The blue colour of the sky, which is visible to human eyes due to the scattering of blue wavelength light by colloidal particles in the atmosphere, is a wonderful illustration of this. The molecular weight of colloidal particles is determined by this feature.


  • The random movement of colloidal particles is described by Brownian motion. The irregular motion, which can be seen with particles as large as 5 m, was attributed to the particles being bombarded by the molecules of the dispersion medium. Because the molecules are too small to perceive, their motion cannot be monitored. The velocity of the particles increases as the particle size decreases. The Brownian movement is reduced and eventually stopped by increasing the viscosity of the medium, which can be performed by adding glycerin.
  • Colloidal particles diffuse naturally from a high-concentration zone to a low-concentration region until the system’s concentration is uniform throughout. The Brownian movement is a direct effect of diffusion. Colloidal particle diffusion is governed by Fick’s first law of diffusion, which states that the amount of material diffusing across a plane of area at any given time is directly proportional to the change in concentration on both sides.
  • The Van’t Hoff Equation, where is the osmotic pressure, c is the concentration of the solute in the system, R is the universal gas constant, and T is the temperature, describes the osmotic pressure of colloidal particles. The osmotic pressure of colloidal particles is directly proportional to all of these components, according to this equation.
  • Because the colloidal particles are always in Brownian motion, as previously stated, they have no tendency to silt. The colloidal particles’ Brownian motion is sufficient to counteract the gravitational force acting on them. As a result, a larger force is required to achieve quantitative and detectable sedimentation of colloidal particles. The ultracentrifuge, which can produce a force one million times that of gravity, is used to do this.
  • Viscosity is a measure of a system’s resistance to flow when it is subjected to a force. When a liquid is more viscous, it takes more force to get it moving and keep it moving at a consistent rate. y, o is the viscosity of the dispersion medium, is the viscosity of the dispersion, and is the volume fraction, and is the viscosity of the colloidal solution is given by an equation developed by Einstein, = o(1 + 2.5), where y, o is the viscosity of the dispersion medium, is the viscosity of the dispersion, and is the volume fraction.


  • The essential idea underpinning four electrokinetic phenomena is the movement of a charged surface with regard to an adjacent liquid phase: electrophoresis, electro-osmosis, sedimentation potential, and streaming potential. Electrophoresis is the phenomenon of charged particles moving across a liquid media when a potential difference is applied. Electro-osmosis is a phenomena in which a charged particle moves relative to a stationary liquid when a potential is applied to it. The formation of a potential difference when charged particles sediment is known as sedimentation potential. The streaming potential is different from electro-osmosis in that it is created by pushing a liquid to flow through a stopper or bed of particles.
  • When sodium chloride is placed in a solution on one side of a semipermeable membrane and a negatively charged colloid with its counter ions R-Na+ is placed on the other, the sodium and chloride ions can freely travel over the barrier, but the colloidal anionic particles cannot.

Colloidal Solution: Purification

There are mainly two major ways for purificationof colloidal solution, i.e., by condensation method (chemical techniques) and by dispersion method (physical techniques).

Condensation Method :

Purification of colloidal solution by condensation method uses the following chemical techniques: Oxidation, Double decomposition, Hydrolysis, Excessive cooling, Exchange of solvent, Change of physical state, etc.

Dispersion Method:

The dispersion method for purification of colloids mainly includes the following physical methods: Mechanical dispersion, Bredig’s Arc Method or by Electrical Dispersion, Peptization.

Colloidal Solution Particle Size

Colloidal particles are larger than simple molecules but small enough to remain suspended. Their colloidal solution particle size range of diameters is between 1 and 1000 nm, i.e. from 109 to 106 m.

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Colloidal Solution: FAQs

Ques. What are some examples of colloidal solutions?
Ans. A colloidal solution is a solution in which a material is equally suspended in a liquid, according to the definition. Gelatin, muddy water, butter, blood, and coloured glass are all examples of colloidal solution.

Ques. What is colloidal solution, and what are its characteristics?
Ans. A colloidal solution is a sort of combination made up of particles ranging in size from 1 to 1000 nanometres. The particles in a colloidal solution are uniformly dispersed. The particles do not settle down throughout this process. One of the most well-known facts concerning colloidal solutions is this.

Ques. Does milk qualify as a colloidal solution?
Ans. Milk is an example of a colloidal solution, in which the phase is fat and the medium is water. Milk is an example of a colloidal solution, in which the phase is fat and the medium is water.

Ques. What is a colloid mixture, exactly?
Ans. Colloids are mixes in which one or more chemicals are scattered throughout a solid, liquid, or gaseous medium as relatively large solid particles or liquid droplets. A colloid’s particles are generally electrically charged and remain scattered and do not settle owing to gravity.

Ques. What exactly is the distinction between a colloid and a solution?
Ans. A colloid is a dispersion medium that contains dispersed or suspended particles. A solution, on the other hand, is a mixture comprising one or more solutes in a solvent. Colloids have two components: dispersed phase and dispersion medium, whereas a solution is a mixture of solute and solvent.

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