Shown below are adsorption isotherms for a gas 'X' at temperatures T1, T2 and T3 : [figure] p and xm represent pressure and extent of adsorption, respectively. The correct order of temperatures for the given adsorption is :
- T1 = T2 > T3
- T1 > T2 > T3
- T3 > T2 > T1
- T1 = T2 = T3
Answer
(3) T3 > T2 > T1
Solution
Physical adsorption of a gas is exothermic: Gas + Solid Gas/Solid; H < 0.
By Le Chatelier's principle, the extent of adsorption xm decreases as temperature increases.
From the graph, at the same pressure: ( xm )T1 > ( xm )T2 > ( xm )T3
T3 > T2 > T1
Answer: (3)