Question

Adsorption of a gas on a surface follows Freundlich adsorption isotherm. Plot of, $log\frac{x}{m}$ versus log p gives a straight line with slope equal to 0.5, then :

[$\frac{x}{m}$ is the mass of the gas adsorbed per gram of adsorbent]

• A. adsorption is proportional to the pressure.
• B. adsorption is proportional to the square of pressure.
• C. adsorption is independent of pressure.
• D. adsorption is proportional to the square root of pressure.

Answer 1

The correct option is D adsorption is proportional to the square root of pressure.

Adsorption of a gas on a surface follows Freundlich adsorption isotherm. Plot of , log $\frac{x}{m}$ versus log P gives a straight line with slope equal to 0.5, then adsorption is proportional to the square root of pressure.

$\frac{x}{m}=k{P}^{1/n}$

$log\frac{x}{m}=logk+1/nlogP$

Slope $=1/n=0.5$

$\frac{x}{m}=k{P}^{0.5}$

$\frac{x}{m}\propto P^{0.5}$
Hence, the option (D) is correct answer.