Why is desorption important for a substance to act as good catalyst?
Desorption is important for a substance to act as a good catalyst so that after the reaction, the products formed on the surface separate out (desorbed) to create free surface again for other reactant molecules to approach the surface and react.
If desorption does not occur then other reactants are left with no space on the catalysts surface for adsorption and reaction will stop.
What is the role of diffusion in heterogeneous catalyst?
Diffusion of gas molecules occur at the surface of catalyst (solid) followed by adsorption. In the same way, the product formed diffuse from the surface of the catalyst leaving the surface free for more reactant molecules to get adsorbed and undergo reaction.
How does a solid catalyst enhance the rate of combination of gaseous molecules?
When gaseous molecules come in contact with the surface of a solid catalyst, a weak chemical bond is formed between the surface (catalyst) molecules and reactant (gas) molecules. Thus, concentration of reactant molecules increases at the surface.
The rate of reaction increases by adsorption of different molecules side by side facilitating the chemical reaction. Adsorption, being exothermic also help in increasing the rate of reaction (chemisorption increases with rise in temperature).
Do the vital functions of the body such as digestion get affected during fever? Explain your answer.
The optimum temperature range for enzymatic activity is 298-310 K, i.e., enzymes are inactive beyond this temperature range (high or low).
Thus, during fever (temperature $>310 \mathrm{~K}$ ) the activity of enzymes may be affected.
Method of formation of solution is given in Column I. Match it with the type of solution given in Column II.
| Column I | Column II | ||
|---|---|---|---|
| A. | Sulphur vapours passed through cold water. | 1. | Normal electrolyte solution |
| B. | Soap mixed with water above critical micelle concentration. | 2. | Molecular colloids |
| c. | White egg whipped with water. | 3. | Associated colloid |
| D. | Soap mixed with water below critical micelle concentration. | 4. | Macromolecular colloids |
A. $\rightarrow(2)$ B. $\rightarrow$ (3) C. $\rightarrow$ (4) D. $\rightarrow$ (1)
A. When sulphur vapours passed through cold water it leads to formation of molecular colloids.
B. When soap is mixed with water above critical micelle concentration it lead to formation of associated colloids.
C. White of egg whipped with water is an example of macromolecular colloids in which high molecular mass proteneous molecule acts as a colloidal particle.
D. Soap mixed with water below critical micelle concentration is known as normal electrolyte solution.