Question

Which of the following represent the plot of $log\left(\frac{x}{m}\right)vsC$ for Freundlich adsorption isotherm in solution phase?
Here,
$\left(\frac{x}{m}\right)$ is extent of adsorption
$C$ is equilibrium concentration

• A.
• B.
• C.
• D.

Answer 1

The correct option is C

Adsorption in solution phase:
Solids can also adsorb solutes from solution.
For example,
when the solution of acetic acid is shaken with charcoal in it, a part of acetic acid is adsorbed on the charcoal and leads to the decrease in concentration of acetic acid in the solution.

Freundlich’s equation approximately describes the behaviour of adsorption from the solution. But for the solution phase, concentration of the solution is taken in account instead of pressure.

$\frac{x}{m}=k{C}^{\frac{1}{n}}..\left(i\right)$
$C$ is equilibrium concentration
k is constant
n is constant
$\frac{x}{m}$ is extent of adsorption

Taking log both sides
$\log \left(\frac{x}{m}\right)=\log \left(k{C}^{\frac{1}{n}}\right)$
$\log \left(\frac{x}{m}\right)=\frac{1}{n}\log C+\log \left(k\right)$
Comparing with
$y=mx+c$
$m=\frac{1}{n}$
$c=\log \left(k\right)$