Colloids: Classification of Colloids.

Colloids are the heterogenous mixture of different particles with a non-soluble tendency ratio that is dispersed in variable phases. The colloid particles are microscopic and cannot be observed without an electron microscope. The colloid has a wide range of differential properties where the behaviour change is observed with the dispersion medium. The classification of colloids is based on their physical properties and nature with solubility with the solvent. Although the particles in the colloids attain a non-uniform density, some particles remain undissolved and settle down at the bottom of the mixture. The types of colloids are according to their physical state, nature of interactions and particle dispersion in different phases. 

Classification of colloids:

The classification of colloids depends upon the nature of the particles involved in the colloidal mixture. The colloidal system functions on the dispersed phase and medium where the non-soluble particles react differently with the separation process and the solute. Here are some of the aspects which put an impact on the classification of the colloids:

• Type of colloids in a physical state in the dispersed phase and the dispersion medium
• Classification according to the nature of interaction among dispersion medium and dispersed phase.
• Classification according to the type of the particles of the dispersed phase.

Classification of colloids in a physical state in the dispersed phase and dispersion medium: 

In the physical condition of colloids, eight categories of colloids are present. These are differentiated according to their physical condition like solid, liquid, and gaseous state in the dispersed phase and dispersion medium. Below are the details:

There are specific names of the colloids according to the variable dispersion medium of the colloids:

Classification according to the nature of interaction among dispersion medium and dispersed phase:

These are the classification of colloids according to the nature of particles’ interaction with solutes and each other. This classification impacts their presence in the dispersed phase and dispersion medium. According to all these aspects, there are two basic types of colloids:

• Lyophobic colloids 
• Lyophilic colloids

Lyophobic colloids: These are colloids where the affinity between the particles of the dispersed phase and dispersion medium is almost negligible. These are the difficult solutions that are formed only in some specific situations. The lyophobic colloids very quickly attain a precipitated state when the electrolyte components are added. Here the aggregation of many types of molecules are needed and are detected with an ultramicroscopic procedure. The highly unstable lyophobic colloids require an assistive tracing of a stabiliser for a stable state. 

Lyophilic colloids: In such a solution, the particles have a high-affinity ratio between the dispersed phase particles and the dispersion medium. The formation of this solution is elementary, and lyophilic colloids react very friendly to the conversions. These are highly reversible forms repeatedly after various transformations. Its formation process is simple by directly mixing the particles and attaining a high stability ratio. The lyophilic colloids cannot be coagulated easily and need more electrolytes. Lyophilic colloids are in an invisible state even under microscopic observation. The particles in the lyophilic colloids are big and considered true molecules. 

Classification according to the type of the particles of the dispersed phase.

In this classification of colloids, the particles depend upon the kind of particles reaction and nature in the dispersed phase. In this category, the colloids are divided into three major types:

• Macromolecular colloids
• Multimolecular colloids
• Associated colloids

Macromolecular colloids: These are the colloids that attain large molecules in the dispersed phase of the mixture. When they occur in the dispersed phase, such colloids reach a specific size in their colloidal range. These molecules are either naturally occurring or artificially created. Starch cellulose gelation is a real example of naturally occurring macromolecular colloids. Whereas plastic, polystyrene, nylon are man-made or artificial macromolecular colloids.

Multimolecular colloids: Multimolecular colloids are colloids where the dissolution or molecules of the particles aggregate together to form the specific colloidal dimensions. The size or diameter of the molecules in the multimolecular colloids are less than 1 nm and are aggregated together with the help of Van der Waals forces. The gold and sulphur molecules are ideal examples of multimolecular colloids. 

Associated colloids: These are the type of colloids that behave as colloids at higher concentrations of particles. The substances in associated colloids act as an electrolyte in the low concentration. All these molecular conditions occur when the molecules are dissolved in the medium state with the aggregation of the particles. In associated collisions, the formed aggregates are called micelles. 

Conclusion:

Above are the classification of colloids in various physical and chemical states in the dispersed phase and dispersion medium. In all these categories of colloids, some of the aggregation of molecules offer the precipitated form of the solution. The coagulation of the molecules is usually attained when the electrolytes are added to the molecules. Therefore, some colloidal solutions acquire a suitable example in practical lives and denote their various aggregation forms.