A: Physical adsorption:
1. The accumulation of gas on the surface of a solid is due to weak
Vander Waals forces.
2. It is multilayered.
3. Enthalpy of adsorption is low.
4. Low temperature is favoured.
Chemical adsorption:
1. The accumulation of gas on the surface of a solid is due to chemical bonds.
2. It is unilayered.
3. Enthalpy of adsorption is high.
4. High temperature is favoured.
Q: Give 4 differences between Lyophilic colloids and Lyophobic colloids.
A: Lyophilic colloids
1. They are formed due to much affinity between dispersed phase and
dispersion medium.
2. They are reversible.
3. They are highly stable.
4. The can not be coagulated easily.
Lyophobic colloids:
1. They are formed due to little affinity between dispersed phase and
dispersion medium.
2. They are irreversible.
3. They are least stable.
4. They can be coagulated easily.
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