When a triatomic gas is adsorbed as atoms on the surface of a solid, the Langmuir adsorption isotherm becomes:

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DSSSB PGT Chemistry (Female) Official Paper (Held On: 06 Jul, 2018 Shift 1)

Answer 1

CONCEPT:

Langmuir Adsorption Isotherm

θ = _KP / (1 + _KP)

The Langmuir adsorption isotherm assumes that adsorption occurs at specific homogeneous sites on the surface of a solid.
When a gas is adsorbed, the fractional surface coverage (θ) is related to the pressure (P) of the gas and a proportionality constant (K).
The general form of the Langmuir adsorption isotherm is:

EXPLANATION:

θ = Kp^1/3 / (1 + Kp^1/3)

When a triatomic gas is adsorbed as atoms on the surface of a solid, it dissociates into three atoms per molecule.
This dissociation alters the relationship between surface coverage and gas pressure. Specifically, the adsorption of the dissociated atoms is proportional to the cube root of the pressure (P^1/3). This changes the Langmuir equation to:
This modified Langmuir adsorption isotherm reflects the dependence of adsorption on the cube root of the gas pressure due to the triatomic nature of the gas and its dissociation into three atoms.
Therefore, the correct Langmuir adsorption equation for a triatomic gas is:
- θ = Kp^1/3 / (1 + Kp^1/3)

Therefore, the correct Langmuir adsorption isotherm for a dissociating triatomic gas is θ = Kp^1/3 / (1 + Kp^1/3), which corresponds to Option 3.