Question

A graph is plotted between $log(x/m)$ and $logp$ 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

Answer: (B)

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:
$\Rightarrow \frac{x}{m}=k\times (p)\frac{1}{n}$
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,
$\Rightarrow \log \left(\frac{x}{m}\right)=\log (k)+\frac{1}{n}\log (p)$
So, the graph can be plotted as shown in the figure.
Hence, the graph shown is Freundlich adsorption isotherm, not Langmuir adsorption isotherm.