Difference between Lyophilic sol and Lyophobic sol
The colloids can be classified into two on the basis of affinity of phases.
i) Lyophilic (solvent loving) colloids and ii) Lyophobic (solvent hating) colloids.
i) Lyophilic colloids:
The colloidal systems in which the particles of the dispersed phase have a great affinity towards the dispersion medium are called lyophilic colloids. (Lyo= liquid, philic =loving). Such colloidal solutions are readily formed when the dispersed phase and the dispersion medium are brought in contact with each other. There are reversible colloids.
When water is the dispersion medium, then the lyophilic colloids are called hydrophilic colloids.
Examples of Lyophilic colloids
Examples of lyophilic colloids are glue, starch, gelatin etc.
ii) Lyophobic colloids:
The colloidal solutions in which the particles of the dispersed phase no affinity for the dispersion medium are called lyophobic colloids. Such colloidal solutions are formed with difficulty. They are irreversible colloids. Such colloidal solutions are formed with difficulty. They are irreversible colloids.
In case the dispersion medium is water, then the lyophobic colloids are hydrophobic colloids.
Examples of Lyphobic colloids
Examples of lyphobic colloids are gold sol, Arsenic (As2S3) sol, Fe(OH)3 etc
Lyophobic sol
1. The sol in which there is a repulsion between the particles of the dispersed phase and the dispersion medium is called a lyophobic sol.
2. It is an irreversible sol.
3. The colloidal particles are clearly visible through an ultra microscope.
4. Under the influence of an electric field the particles of the dispersed phase migrate only in one direction.
Viscosity of the sol is nearly the same as that of dispersion medium.
6. Surface tension of the sol is nearly the same as that of the dispersion medium.
7. The colloidal particles can be easily coagulated.
Lyophilic Sol
1. The sol in which there is an attraction between particles of the dispersed phase and the dispersion medium is called a lyophilic sol.
2. It is a reversible sol.
3. The colloidal particles are barely visible through an ultra microscope..
4. Under the influence of an electric field the particles of the dispersed phase may migrate in either direction or may not migrate at all.
5. The viscosity of the sol is higher than the viscosity of the dispersion medium.
6. Surface tension of the sol is lower that of the dispersion medium.
7. The colloidal particles cannot be easily coagulated.
Comparison of Lyophilic and Lyophobic sols
Characters
| Lyophilic colloids
| Lyophobic colloids
|
|---|---|---|
Nature
| Reversible
| Irreversible
|
Preparation
| Readily formed by direct mixing
| Formed only by special methods
|
Stability
| Self stabilised
| Unstable and hence require stabilizers.
|
Viscocity
| Much higher than that of the medium
| Same as that of the medium
|
Surface tension
| Lower than, that of the dispersion medium
| Nearly the same as that of the medium
|
Hydration
| Particles are heavily hydrated
| Particles are not appreciably hydrated.
|
Action of electrolytes
| Large amount of electolytes can cause precipitation
| Small amount of electrolytes can cause precipitation.
|
Tyndall effect
| Do not show
| it shows
|
Lyophilic vs Lyophobic sols
Difference between
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