How physical adsorption will be effected by increase in temperature

Options

A. It will decrease
B. It will increase
C. First increase then decrease
D. None of these

Answer

**Step-by-Step Solution:**

1. **Understanding Physical Adsorption:**
- Physical adsorption, also known as physisorption, is the process where gas molecules adhere to a solid surface through weak van der Waals forces. This process is generally reversible and occurs at lower temperatures.

2. **Nature of Physical Adsorption:**
- Physical adsorption is an exothermic process. This means that when adsorption occurs, heat is released. The energy released during the adsorption process is due to the formation of weak intermolecular forces between the adsorbate (gas molecules) and the adsorbent (solid surface).

3. **Le Chatelier's Principle:**
- According to Le Chatelier's principle, if a system at equilibrium is subjected to a change in temperature, the equilibrium will shift in a direction that counteracts the change. For exothermic processes, increasing the temperature will shift the equilibrium to favor the reactants, thereby reducing the extent of adsorption.

4. **Effect of Temperature Increase:**
- When the temperature increases, the kinetic energy of the gas molecules also increases. This increased kinetic energy allows the gas molecules to overcome the weak van der Waals forces that hold them to the surface of the adsorbent. As a result, the extent of physical adsorption decreases with an increase in temperature.

5. **Graphical Representation:**
- A graph can be plotted with the extent of adsorption (θ) on the y-axis and temperature (T) on the x-axis. The graph will show a downward trend, indicating that as temperature increases, the extent of physical adsorption decreases.

6. **Conclusion:**
- Therefore, the conclusion is that an increase in temperature leads to a decrease in physical adsorption.

**Final Answer:**
- Physical adsorption decreases with an increase in temperature.

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