Question

A graph is plotted between log (x/m) and log p according to the equation $\frac{x}{m}=k{p}^{1/n}$
Which of the following statements about this graph is not correct?

• A. The figure shows Freundlich adsorption isotherm.
• B. The figure shows Langmuir adsorption isotherm.
• C. The adsorption varies directly with pressure.
• D. The factor 1/n can have values between 0 and 1.

Answer 1

The correct option is B The figure shows Langmuir adsorption isotherm.

Freundlich gave an empirical relationship between the quantity of gas adsorbed by a unit mass of solid adsorbent and pressure at a particular temperature. The relationship can be expressed by the following equation:

$⟹$ $\frac{x}{m}=k\times$$(p{)}^{\frac{1}{n}}$

where x is the mass of the gas adsorbed on mass m of the adsorbent at pressure P, k and n are constants which depend on the nature of the adsorbent and the gas at a particular temperature.

On taking logarithm on both sides of the equation,

$⟹log\left(\frac{x}{m}\right)=log\left(k\right)+\frac{1}{n}log\left(p\right)$

So, the graph can be plotted as shown in the figure.

Hence, the graph shown is Freundlich adsorption isotherm, not Langmuir adsorption isotherm.