What is an Adsorption Isotherm? Describe Freundlich Adsorption Isotherm

Adsorption isotherm:

• “The variation in the amount of gas adsorbed by the adsorbent with pressure at constant temperature can be expressed by means of a curve termed as adsorption isotherm.”
• “Freundlich, in 1909, gave an empirical relationship between the quantity of gas adsorbed by unit mass of solid adsorbent and pressure at a particular temperature.”
• The relationship can be expressed by the following equation:

$\frac{x}{m}=k.p^{1/n}\left(n>1\right)$,

• where $x$ is the mass of the gas adsorbed on mass $m$ of the adsorbent at pressure $p\mathit{,}\mathit{}k\mathrm{and}n$ are constants which depend on the nature of the adsorbent and gas at a particular temperature.