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The Langmuir adsorption isotherm is deduced using the assumption
A
the adsorption sites are equivalent in their ability to adsorb the particles
B
the heat of adsorption varies with coverage
C
the adsorbed molecules interact with each other
D
the adsorption takes place in multilayers
Detailed Solution
The Langmuir adsorption isotherm is based on the following assumptions.
Every adsorption site is equivalent, and the ability of a particle to bind at a site is independent of whether or not the nearby sites are occupied.
This means the adsorbed molecules do not interact with each other, and the heat of adsorption is the same for all sites and does not vary with coverage.
Adsorption takes place only until a single layer is formed; it is monolayer adsorption, not multilayer adsorption.
There is a dynamic equilibrium between adsorption and desorption.
These lead to $\dfrac{x}{m} = \dfrac{aP}{1 + bP}$.
So the correct assumption is that the adsorption sites are equivalent in their ability to adsorb the particles.
Every adsorption site is equivalent, and the ability of a particle to bind at a site is independent of whether or not the nearby sites are occupied.
This means the adsorbed molecules do not interact with each other, and the heat of adsorption is the same for all sites and does not vary with coverage.
Adsorption takes place only until a single layer is formed; it is monolayer adsorption, not multilayer adsorption.
There is a dynamic equilibrium between adsorption and desorption.
These lead to $\dfrac{x}{m} = \dfrac{aP}{1 + bP}$.
So the correct assumption is that the adsorption sites are equivalent in their ability to adsorb the particles.