Question

Physical adsorption is inversely proportional to
A. Temperature
B. Pressure
C. Concentration
D. All

Answer 1

Hint: Physical adsorption depends on various factors. It depends on pressure, temperature and surface area. Physical adsorption is directly proportional to the pressure and concentration but it follows some irregular trend with temperature.

Complete Step by Step Solution:
In the method of physical adsorption, the adsorption takes place between the adsorbate and adsorbent due to weak hydrogen bonding or Van Der Waal’s force.
Physical adsorption is inversely proportional to temperature. It increases with decrease in temperature because as the temperature increases the bond vibration increases so, the adsorption decreases.
Physical adsorption is directly proportional to pressure and concentration. As these increases the adsorption also increases.
Thus the correct option is A.

Additional Information: The properties of physical adsorption are as follows-
1. It has weak forces like vander waals force or hydrogen bonding between adsorbate and adsorbent.
 2. Physical adsorption is reversible in nature.
3. Physical adsorption depends on the surface area of the adsorbent because as the surface area of the adsorbent will increase, physical adsorption additionally will increase.
4. Physical adsorption is the slowest process.
5. It is not independent of temperature. It increases with a decrease in temperature.
6. It is highly specific.
7. It is spontaneous and has negative enthalpy and entropy.

Note: The atoms of the bond present in physical adsorption undergo bond vibration which increases the entropy or randomness of the system. The entropy is inversely proportional to adsorption.