semester 2 Nidhi Sanket

1. Submitted By – NIDHI SANKET
M.Sc Chemistry Semester II
Department Of Chemistry
S.P.C. Govt. College, Ajmer
ADSORPTION

2. CONTENTS
• ADSORPTION
• ADSORPTION AND ABSORPTION
• SOME BASIC TERMS WHICH ARE USED IN ADSORPTION
• MECHANISM OF ADSORPTION
• CHARACTERISTICS OF ADSORPTION
• TYPES OF ADSORPTION -
 PHYSISORPTION
CHEMISORPTION
• FACTORS AFFECTING ADSORPTION
• APPLICATIONS OF ADSORPTION

5. SOME BASIC TERMS WHICH ARE USED IN
ADSORPTION
ADSORBENT - Surface of a substance on which adsorbate adsorbs
. For e.g., charcoal, silica gel etc
ADSORBATE - Substance that is adsorbed . For e,g., N2 , O2 , H2

6. SORPTION
• A process in which both
adsorption and absorption take
place simultaneously , it is called
sorption. E.g., when hydrogen is
taken up by the charcoal , it first
condenses on its surface . This is
adsorption . After sometime ,
hydrogen diffuses slowly into the
interior of the charcoal forming a
true solid solution . This is
absorption . So , the charcoal
has absorbed as well as
adsorbed hydrogen gas .
OCCLUSION
• The adsorption of a gas on the
surface of a metal is called
occlusion . According to Graham
who introduced the term occlusion
said that it has a significance
similar to sorption .
• E.g., Hydrogen is adsorbed on
the surface of nickel or palladium .

14. FACTORS AFFECTING ADSORPTION
• Nature of adsorbent (solid) and adsorbate(gas) – In
general,easily liqueliable gases e.g.,CO2 ,NH3 ,Cl2 and
SO2 etc . are adsorbed to a greater extent than the
permanent gases e.g.,H2,O2,N2 etc
Porous and finely powdered solid e.g.,charcoal adsorb
more as compared to hard non porous material .
• Surface area of adsorbent - More the surface
area ,greater is the extent of adsorption .

15. • ACTIVATION OF( SOLID) ADSORBENT
• Increasing adsorbing power of adsorbent - making
surface rough / increasing surface area (powder)
- removing already adsorbed gases .

16. • EFFECT OF PRESSURE
•An increase in the pressure of adsorbate gas increases the extent of adsorption .
•At low temperature , the extent of adsorption increases rapidly with pressure .
•Moderate Pressure , the extent of adsorption is found to be directly proportional
to the pressure .
•At higher pressure , after a certain pressure(closer to saturation pressure) there
is no increase in adsorption .

17. • EFFECT OF TEMPERATURE
• As adsorption is exothermic , so according to Le- Chatelier’s
principle, adsorption increases with decrease in temperature.
• A physisorption isobar shows decrease in extent of
adsorption as temperature rises .
• The isobar of chemisorption show an increase in beginning
and then decreases as temperature rises .

18. Reference
• Advance Physical Chemistry,22nd edition, Gurtu – Gurtu
• Keith J. Laidler, chemical Kinetics, Third edition, Pearson
Education, 2004
• Youtube