What is an adsorption isotherm? Describe Freundlich adsorption isotherm.

Adsorption Isotherm- The variation in the amount of a gas adsorbed by the adsorbent with pressure at constant temperature can be expressed by the curve . This curve is known as Adsorption Isotherm.

Freundlich 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.  x/m = k P1/n      Where x is the mass of gas adsorbed on mass m of the adsorbent pressure P. k and n are constants depend on nature of adsorbent.This relationship is expressed in the form of curves where the mass of the gas adsorbed per gram of adsorbent is plotted against pressure.