Freundlich Adsorption Isotherm and the value of 1/n

Freundlich Adsorption Isotherm is a mathematical model that describes the adsorption of a solute onto the surface of a solid adsorbent. It was developed by German chemist Herbert Freundlich in 1906 and is widely used to study the adsorption behavior of various substances.

The Freundlich equation is given as:

x/m = K * C^(1/n)

Where:
- x/m is the amount of solute adsorbed per unit mass of adsorbent (adsorption density)
- K is a constant related to the adsorption capacity of the adsorbent
- C is the equilibrium concentration of the solute in the solution
- 1/n is a constant related to the adsorption intensity or surface heterogeneity

1. Physical Adsorption
Physical adsorption (also known as physisorption) is a type of adsorption that occurs due to weak van der Waals forces between the solute molecule and the adsorbent surface. It is a reversible process and typically occurs at low temperatures. In physical adsorption, the value of 1/n is generally close to 1.

2. Chemisorption
Chemisorption is a type of adsorption that involves the formation of chemical bonds between the solute molecule and the adsorbent surface. It is a more specific and stronger interaction compared to physical adsorption. Chemisorption is often irreversible and occurs at higher temperatures. In chemisorption, the value of 1/n is also close to 1.

3. Value of 1/n in Freundlich Adsorption Isotherm
The value of 1/n in the Freundlich equation determines the shape of the adsorption isotherm curve. It represents the degree of nonlinearity in the adsorption process.

In general, the value of 1/n is between 0 and 1 for both physical adsorption and chemisorption. This indicates that the adsorption process is nonlinear and the adsorbent surface is heterogeneous. A value of 1/n closer to 1 suggests a more favorable adsorption process.

The value of 1/n can vary depending on the nature of the solute, adsorbent, and the specific conditions of the adsorption process. It is typically determined experimentally by fitting the Freundlich equation to the experimental data.

In summary, the correct answer is option 'C' - the value of 1/n is between 0 and 1 in all cases in the Freundlich Adsorption Isotherm.

Freundlich isotherm only approximately explains the behaviour of adsorption. The value of 1/n can be between 0 and 1, therefore the equation holds good only over a limited range of pressure. When 1/n = 0, x/m is constant, the adsorption is independent of pressure