The discontinuous phase distributes throughout the continuous phase. Overview and Key Difference 2. What is Colloid 3. What is Emulsion 4. A colloid is a homogeneous non-crystalline substance consisting of large molecules or ultramicroscopic particles of one substance dispersed through a second substance.
The dispersed particles do not settle down spontaneously because colloids are very stable. There are several different categories of colloids that are grouped based on different parameters. The four major categories are as follows:. In addition, there are three forms of colloids; multimolecular colloids, macromolecular colloids, and micelles. This classification categorizes colloids according to the particle size and behavior of those particles in a colloid. A multimolecular colloid forms if the molecules of a compound aggregate when we dissolve the compound in a suitable solvent.
In a macromolecular colloid, the individual particles are large enough to call this a colloid. The particles of solute are of molecular size dimensions and do not scatter a light beam passing through it.
As the composition is homogeneous it is not possible to separate the solute from the solvent by filtration. The only option available is to resort to distillation which removes the solvent and leaves behind a solid residue of the solute.
Most people are confused about what suspension solution is. Suspensions are obtained when insoluble solid particles are dispersed in a liquid medium. On shaking the solute particles can be evenly dispersed in the medium but if left undisturbed the solute particles which range from 0. A colloid results when particles ranging between 1 and nanometers in diameter are dispersed in the liquid solvent.
A colloid is a homogeneous mixture and the solute does not settle out on standing. Colloids can be distinguished from solutions as they exhibit light scattering.
Milk is an example of a colloid solution which consists of fat particles evenly distributed in water. An emulsion like a colloid comprises of a dispersion of two or more immiscible liquids. Oil and water are immiscible and form emulsions when mixed and shaken. Minute oil droplets evenly disperse throughout the water. Due to the phenomenon of distortion of light emulsions generally appear cloudy. Dilute emulsions often appears bluish due to greater scatter of lower wavelengths of light.
It is possible to disperse any of the liquids in the other such as oil and water or water in oil. The minor component does not separate from the major component even if left to stand undisturbed indefinitely. Some emulsions tend to form a film over another phase in the solution to form globules that repel one another allowing them to remain suspended or dispersed indefinitely.
The terms colloid and emulsion are often used synonymously but it should be kept in mind that emulsions result when immiscible liquids are mixed whereas in a colloid solution it can be a liquid or solid dispersion in another liquid.
In other words, an emulsion can be termed as a colloid but all colloids are not emulsions. A few factors that can help differentiate between suspension and emulsion are:. Another contrasting point here is the reaction to filtration. Where suspension particles get separated with filtration, there is no effect of the technique on the emulsion.
Apart from all these, you may also hear the term dispersion solutions. These systems basically have two materials. If the dispersed particles are large enough to undergo the process of sedimentation, the system is called a suspension. Similarly, the dispersion can be divided into various other systems based on the size of particles dispersed in the continuous phase. We hope you understood these terms and can use them appropriately! Want to learn more about the laboratory terms, register for our courses.
Common suspensions include sand in water, dust in air, and droplets of oil in air. Particles in a suspension are larger than those in a solutions; they are visible under a microscope and can often be seen with the naked eye. Particles in a suspension will settle out if the suspension is allowed to stand undisturbed.
Many particles of a suspension can be separated through a filter. An example of a simple suspension would be flour in water, or sand in water. A colloid is a type of mixture intermediate between a homogeneous mixture also called a solution and a heterogeneous mixture with properties also intermediate between the two. The particles in a colloid can be solid, liquid or bubbles of gas.
The medium that they are suspended in can be a solid, liquid or gas although gas colloids cannot be suspended in gas. The particles are approximately 10 to 10, angstroms in size and generally cannot be filtered, or settled out in an easy manner. Colloids may be colored or translucent because of the Tyndall effect, which is the scattering of light by particles in the colloid. Colloid particles may be seen in a beam of light such as dust in air in a "shaft" of sunlight.
Brownian movement may be used to distinguish between solutions and colloids. Brownian motion is the random movement of colloidal particles suspended in a liquid or gas, caused by collisions with molecules of the surrounding medium. The particles in solutions and colloids are in constant motion. However colloid particles are large enough to be observed and are small enough to still be affect by the random molecular collisions.
Colloid particles resist settling rapidly to the bottom of a vessel due to Brownian motion. Emulsions are an example of colloids composed of tiny particles suspended in another immiscible unmixable material.
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