Chemistry Practicals Class 12
Preparation of Lyophilic and Lyophobic Sols
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- In this surface chemistry practical, you will learn the terms colloids, lyophilic and lyophobic colloids.
- You will acquire the skills to prepare lyophilic sols using starch, gum and egg albumin.
- You will acquire the skill to prepare lyophobic sols using ferric chloride, aluminium chloride and arsenious oxide.
- All the experiment steps and procedures will help you understand the chemical reactions involved in synthesising sols.
- You will understand the interactions of the dispersed phase and dispersion medium in lyophilic and lyophobic sols.
- In this chemistry virtual lab, you will learn the surface chemistry of colloids while conducting or performing science experiments.
A two-phase heterogeneous mixture consists of one dispersed phase, and the dispersion medium. Such a system is known as a colloidal system. The dispersed phase is a component present in a small proportion. The dispersion medium is present in large proportion in the system. The stable colloid is one in which the dispersed phase remains suspended throughout the dispersion medium.
Based on the physical states of the dispersed phase and dispersion medium, colloids are further classified as sols (colloidal sols), in which the dispersed phase is solid, and the dispersion medium is liquid.
Lyophilic and lyophobic sols are the two types of sols, classified based on the nature of interactions between the dispersed phase and dispersion medium.
The word ‘lyophilic’ suggests ‘liquid loving’ or ‘solvent loving’, also known as intrinsic colloids. In this sol, there is a strong affinity between the dispersed phase and dispersion medium due to the formation of a large number of hydrogen bonds. Lyophilic colloids are prepared directly by mixing substances like gum, starch, etc., with a suitable dispersion medium (liquid).
The word ‘lyophobic’ suggests ‘liquid hating’ or ‘solvent hating’. The metals, their sulphides and hydroxides in a suitable dispersion medium form a lyophobic sol. The difference between lyophilic and lyophobic colloids is that the lyophilic sols cannot be prepared like lyophilic sols by mixing dispersed phases in the dispersion medium. Some special chemical and non-chemical methods are used for their preparation. Lyophobic colloids are readily precipitated (or coagulated) by adding some reagent and electrolyte or by shaking and heating; hence, these sols are unstable.
Requirements for this Science Experiment
⦁ Pestle and Mortar ⦁ Whatman Filter Paper ⦁ Funnel ⦁ Beakers ⦁ Conical Flask ⦁ Round Bottom Flask ⦁ Test Tubes ⦁ Droppers ⦁ Burette Stand ⦁ Weighing Balance ⦁ Bunsen Burner ⦁ Tripod Stand ⦁ Wire Gauze ⦁ Glass Rod