What is adsorption isotherm ?

Explanation

Adsorption Isotherm. It Represents the variation of the mass of the gas adsorbed per gram of the adsorbent with pressure at constant temperature.
The graph between extent of adsorption (x/m) and temperature (t), keeping pressure constant is called adsorption isobar.
Freundlich adsorption isotherm. (Variation of extent of adsorption with pressure at constant temperature): The variation of extent of adsorption with pressure can be expressed by adsorption isotherm as shown in figure where x is the mass or adsorbate and m is the mass of adsorbent and x /m gives extent of adsorption . The inspection of the graph reveals the following facts :(i) At low pressure , the graph is almost straight line which indicates that x/m is directly proportional to the pressure . This may be expressed as :
`x/m prop p ` or `x/m = kp`
where k is constant .

(ii) At high pressure, the graph becomes almost a straight line parallel to the X-axis which means that x/ m becomes independent of pressure. This may be expressed as:
`x/m` = cosntant or `x/m = kp^0`
(iii) In the intermediate range of pressure, x/m will depend upon the power of pressure which lies between 0 to 1. This may be expressed as:
`x/m prop p^(1//n) ` or `x/m = kp^(1//n)`
where 1/n can take any value between 0 and 1 depending upon the pressure.