Classification Based on Properties of Sol Particle

A sol is a colloid with suspended particles in the solvent medium. There is a wide variety of particle sizes in the sols. These are prepared by different chemical processes such as condensation or dispersion. They have the tendency to show the Tyndall Effect (scattering of light through particles present in the solvent). Forms of colloids are widely found in nature as well as in artificial materials. There is a wide variety of utilisation of colloids at the industrial level. In this article, we will learn about the features of colloids, the properties of sol particles, and answer some sol particle questions.  

Properties of Sol Particles 

Sol is also known as colloids. A sol is composed when large molecules (solid) are mixed with fluids (liquid) in chemistry. This consists of a lot of materials around us. 

Significant properties of sol particles are mentioned below: 

• It is a kind of heterogeneous mixture
• The size of sol particles is tiny 
• Colloids can scatter the light and show the Tyndall Effect 
• The components cannot be separated by filter paper 

Different forms of colloids are present all around us, in natural as well as in artificial particles. Colloids can be utilised in a variety of ways in industries. Sol or colloids are divided into different categories, and we will learn about them in the following passages.

Classification of Colloids 

Dispersed Phase and Dispersion Medium Relationship 

Hydrophilic Colloids

In this kind of sol, colloidal particles are attracted towards the water. It is also known as the hydrocolloid. They are water-loving in nature, for instance, agar, pectin, etc. They are irreversible and reversible. For example, in the case of agar, it is reversible in nature and can be extracted through heating or cooling. The main source of hydrophilic colloids is natural substances. They are used in the field of medicine. 

Hydrophobic Colloids

These colloids are repelled against the water. They are also known as irreversible sols, for instance, gold, clay, etc. Because of the tendency of particles not to attract towards the solvent material, they are unstable in nature. 

On the Basis of Dispersed Phase 

Under this category, there are three types of colloids:

• Multimolecular Colloids

In this kind of colloid, the solution is made up of a large number of particles or small molecules in dispersed media. The particles are interlinked with each other through Van der Waals force. For example, gold sol. 

• Macromolecular Colloids

When many molecular masses are dissolved into the dispersed media, the colloids are called macromolecular colloids. They are also referred to as lyophilic colloids. They have higher molecular masses than multimolecular colloids. For example, starch, gelatin, cellulose, etc. 

• Associated Colloids (Micelles)

Many colloids show both properties, strong electrolytes and colloids, depending upon their concentration. In this kind of colloid, micelles are formed. The concentration on which colloids formed is called critical micellar concentration. These kinds of colloids are also known as associated colloids. 

Based on the State of Dispersed and Dispersion Medium 

For Liquid Dispersion Medium

• Foams

Gas is the dispersed medium in this kind of colloid. This colloidal system consists of particles as gas bubbles and liquid as a medium. This would have a spongy or rigid kind of material. For example, shaving cream. 

• Emulsions

In this kind of colloid, the liquid is the dispersed phase. When some droplets of one liquid are mixed with the immiscible liquid, it is known as an emulsion. The range of the diameter of droplets is from 10-4 to 10-6 cm. For example, milk. 

For Gaseous Dispersion Medium 

• Liquid Aerosol

In this, the liquid is the dispersed phase. For example, fog, mist, etc. 

• Solid Aerosol

In this, solid is the dispersed phase. When minute particles of a solid substance are mixed with the gaseous element, it is known as solid aerosols. For example, smoke. 

For Solid Dispersion Medium

• Solid Foam

In this type of colloid, solid is the dispersed medium. For example, pumice. 

• Gel

In this type of colloid, the liquid is the dispersed medium and dispersed phase is solid, for instance, agar, etc. It is a fruit jelly or elastic type of substance, or solid and non-flexible also. In this, the liquid medium behaves like a solid. Sometimes, contraction causes the separation of liquid from it, and the process is known as syneresis. 

• Solid Sol

In this type of colloid, solid is the dispersed medium. For example, cranberry glass. 

Conclusion

Colloids are widely used in various processes, and we extract them mainly from natural resources. Sol is a colloid with suspended particles in the solvent medium. These are prepared by different chemical processes such as condensation or dispersion. They show the Tyndall Effect (scattering of light through particles present in the solvent). All colloids have two phases, i.e., a dispersed phase and a dispersion medium. Based on types of phases and dispersion, colloids are divided mainly into three categories.