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Classification of colloids & comparative account of their general properties

There are two phases (dispersed phase and diffusion medium) in a colloid. The colloids' particles have diameters ranging from 1 to 1000 nm.

Dispersed Phase and Dispersed Medium

There are two phases (dispersed phase and diffusion medium) in a colloid. The colloids' particles have diameters ranging from 1 to 1000 nm. The solution is full of them.

The dispersed phase refers to the compounds distributed in the solution, while the dispersion medium refers to the solution in which they are disseminated.

Colloids and Their Subtypes

The dispersed phase and the medium are used to classify colloids.

To begin, colloids are classified depending on the types of particles in the dispersed phase as follows:

Multimolecular colloids

When smaller molecules of material or numerous atoms dissolve, they mix to produce a species of colloidal size. A multimolecular colloidal species is a result.

Example - The Sulphur solution, for example, includes particles containing thousands of S8.

Colloids with Macromolecular Structure

The macromolecules in this class of colloids create a solution with a suitable solvent. The particles in this macromolecular solution are colloidal in nature. As a result, macromolecular colloids are another name for this solution. The colloids produced here are comparable to the real solution in many aspects and are highly stable.

Example: Starch, proteins, enzymes, and cellulose are examples of natural macromolecular colloids, whereas polyethene, synthetic rubber, and other artificial macromolecules are examples of synthetic macromolecules.

Colloids That Are Related

Some compounds behave as strong electrolytes when present in low concentrations, yet as colloidal sols when present in high concentrations. Particles agglomerate in larger concentrations, exhibiting colloidal behavior. These aggregated particles are referred to as micelles. Colloids that are related can sometimes be called related colloids.

Based on how the dispersion medium interacts with the dispersed phase, colloids are classified as either lyophilic or lyophobic.

When the dispersed phase is affine to the dispersion medium, it is termed a lyophilic colloid. Lyo and philic are Greek words that mean 'liquid' and 'loving,' respectively. They are also difficult to coagulate because of their stability. The colloids may belong to the category of intrinsic colloids. Examples include flour, rubber, protein, and so forth.

Lyophobic dispersion is one that does not have an affinity for the dispersing medium. Lyo and phobic are Greek terms that denote 'liquid' and 'fear', respectively. Due to their lack of colloid formation abilities, they require the application of specialized techniques in order to form. They are unstable and require stabilizing medications to survive. Extrinsic colloids are another name for them.

Comparative account of their general properties

Physical properties

  • The colloidal solution has a heterogeneous, or unlike, character. These solutions are divided into two stages:
  1. The medium is dispersed.
  2. The dispersed phase
  • Despite the fact that colloidal dispersions defy description (nature), the scattered pieces are undetectable to the naked eye. This is because the particles in the solution are tiny in size.
  • The wavelength of light absorbed in the dispersion will vary in hue depending on the particle size in the solution. A yellow colour is produced by little particles in the solution.
  • Because of their small size, colloidal pieces can readily flow through standard filter paper. Filtering these particles, however, may be achieved with membranes such as animal skin, cellophane, and ultrafilters.

Electrical properties

Electrophoresis: This is a method of forcing colloidal particles to migrate by applying an electric field to a colloidal fluid. The charge of the particles may be anticipated based on the buildup near the electrodes. If the particles are gathered near a negative electrode, their charge is positive, and vice versa.

A colloidal solution is electro-osmosed when an electric field is applied to the dispersion medium, causing the particles to stop moving.

Optical properties

Tyndall's effect is described as the phenomenon of light scattering caused by colloidal particles. A particle in the solution has absorbed light. Once the light is absorbed, a portion of it is spread in all directions. This effect can be seen as a result of scattering.

Kinetic properties

When the colloidal dispersion is examined with an ultra-microscope, it is evident that the particles are constantly moving in the fluid. Brownian effect refers to the random zigzag movement of particles in a colloidal fluid. This movement is primarily caused by the unique bombardment of colloidal particles by molecules in the dispersion media.
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