Question

Freundlich adsorption isotherm fails at which of the following conditions?

• A. High temperature
• B. Low temperature
• C. High pressure
• D. Low pressure

Hint:

Freundlich isotherm is suitable for low to moderate pressures and heterogeneous surfaces.

Answer 1

The Correct Option is C

Step 1: Recall Freundlich's empirical formula.
Freundlich isotherm: \(\frac{x}{m} = kP^{1/n}\). It predicts adsorption rises continuously with pressure and has no built-in upper limit.

Step 2: Identify the failure point.
At high pressure, the adsorbent surface becomes saturated (monolayer complete) and adsorption levels off. Freundlich's formula cannot account for this saturation, so it fails at high pressures.
\[ \boxed{\text{High pressure}} \]