Classification of Colloids - Types of Colloids, Definition, FAQs

What exactly is a colloid?

A colloid is a heterogeneous mixture in which minute particles of one component are scattered in a dispersion medium of another substance.
The tiny particles in this combination range in size from 1 to 1000 nanometres in diameter, but they remain suspended and do not settle to the bottom. They can be seen with an optical or electron microscope (smaller particles).

A dispersed phase and a dispersion medium make up colloids. They're divided into groups based on the features of the dispersed phase and the medium. Let us discover more about them right now.

The following is the IUPAC definition of colloid:

“A colloidal state is a condition of dispersion in which molecules or poly molecule particles with at least one dimension between 1 nanometre and 1 micrometre are distributed in a medium.”

Dispersion Medium and Dispersed Phase

Definition of colloidal dispersion

A colloid is a mixture in which a fine-particle-containing substance (dispersed phase) is combined with another component (dispersion medium). The colloids' particles range in size from 1 to 1000 nm in diameter. Because the particles of the solution do not mix or settle down, the solution is called colloidal dispersion. In the solution, they are disseminated.

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Definition of dispersed phase

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

Depending on the state of dispersion and the medium of dispersion

The following classification of colloid system can be used depending on the state of dispersed particles and the dispersion medium.

When the Dispersion Medium Is Liquid Foams – When the dispersion medium is liquid foams. Whipped cream, shaving cream, and other similar products are examples.

When the dispersed phase is liquid, it is called an emulsion. Milk, mayonnaise, and other foods are examples.

When the scattered phase is solid, it is called sol. Blood, pigmented ink, and other materials are examples.

When there is a gaseous dispersion medium

When the dispersed phase is liquid, it is referred to as a liquid aerosol. Fog, mist, hair sprays, and other similar products are examples.

When the dispersed phase is solid, it is referred to as a solid aerosol. Smoke, ice clouds, and more examples come to mind

Colloids are classified

When the dispersed medium is a gas, it is referred to as solid foam. Styrofoam, pumice, and other materials are examples.

When the distributed media is liquid, it is called a gel. Agar, gelatin, and other similar substances are examples.

When the scattered medium is solid, it is called solid sol. Cranberry glass is one example.

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Classification of colloids

Colloids are classified based on the nature of the interaction between the dispersed phase and the dispersion. Medium

Colloids that are hydrophilic: These are colloids that like to be in the water. The water attracts the colloidal particles. Reversible sols are another name for them. Agar, gelatin, pectin, and other similar substances are examples.

Hydrophobic colloids are the polar opposites of hydrophilic colloids. The water repels the colloid particles. Irreversible sols is another name for them. Gold sols, clay particles, and other materials are examples.

Based on the Dispersed Phase Particle Type

Colloidal solutions can be categorised into three categories based on how different chemicals creating colloidal solutions acquire particle sizes in this range.

The classification of colloids is done based on the types of colloids. The following are the categories:

Types of colloids

Colloids: multimolecular colloids

Colloids: macromolecular colloids

Colloids: associated colloids

Multimolecular Colloids

A solution created by the aggregation of a high number of atoms or tiny molecules (with diameters less than 1 nm) in a dispersed medium. Van der Waal forces hold the dispersed particles together.

Example:

Sulphur sol, and gold sol.

Macromolecular Colloids

Molecules with extremely high molecular weights combine to form macromolecules, which are exceedingly big molecules.

The resulting colloidal solutions are known as macromolecular colloids when such compounds are dispersed in a suitable dispersion medium. As a result, macromolecular colloids have a large molecular mass.

Lyophilic colloids are often macromolecular in nature.

Natural macromolecules including starch, proteins, gelatin, cellulose, nucleic acids, and others, as well as synthetic polymers like polyethylene, polypropylene, and synthetic rubber, create macromolecular colloids when dispersed in suitable solvents.

Associated Colloids

When present in low quantities, some compounds behave as strong electrolytes, yet when present in high concentrations, they behave as colloidal sols. Particles agglomerate and demonstrate colloidal behaviour at greater concentrations. Micelles are microscopic clumps of collected particles. Associated colloids are another name for them. Micelles are formed above a certain temperature, known as the Kraft temperature (Tk), as well as a certain concentration, known as the crucial micelle concentration. By diluting the colloids, they can be converted. Soaps and synthetic detergents are a couple of examples of related colloids.

Classification of colloids based on interaction medium

Colloids can also be classed according on how the dispersed phase interacts with the medium:

Hydrophilic colloids: Colloids that love or are attracted to water are known as hydrophilic. Reversible sols are another name for them.

Agar, gelatin, and pectin are some examples.

Hydrophobic Colloid: These are the polar opposite of hydrophobic and repel water. Irreversible sols are another name for these.

Gold sols with clay particles, for example.

Colloids are characterised as lyophilic or lyophobic depending on the nature of the interaction between the dispersion medium and the dispersed phase.

Lyophilic

A lyophilic colloid is one in which the dispersed phase has an affinity for the dispersion medium. The words lyo and philic, respectively, signify "liquid" and "loving." Even if the dispersed phase and the dispersion medium are separated, they can easily be reconstituted by simply mixing them together. Furthermore, because of their sturdy nature, they are difficult to coagulate. Intrinsic colloids are another name for them. Starch, rubber, protein, and other materials are examples.

Lyophobic

A lyophobic colloid is one in which the dispersed phase has little or no affinity for the dispersion medium. The words lyo and phobic, respectively, denote "liquid" and "fear." As a result, they despise liquids. Because the dispersed phase does not readily form a colloid with the dispersion medium, they are difficult to manufacture and necessitate the employment of special techniques. They are brittle and require stabilising substances to stay alive. Extrinsic colloids are another name for them. Sols of metals such as silver and gold, as well as sols of metallic hydroxides, are examples.

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