Adsorption

Question 1

What is Adsorption?

Answer 1

• Accumulation of substances at an interface, without undergoing any chemical reaction
• Material adsorbed forms a surface or interfacial layer

Question 2

Describe Adsorption of Gas onto a Solid and discuss the types of binding

Answer 2

• Reversible
• Rapid equilibrium achieved
• Types of binding:
  
  • Ion-dipole
  • Dipole-dipole
  • Van der Waals

Question 3

Define Adsorbent (Substrate)

Answer 3

The solid that provides the surface for adsorption - high surface area

Question 4

Define Adsorbate

Answer 4

The gas or liquid molecules that are adsorbing

Question 5

Define Surface Coverage θ

Answer 5

• Completely or partially covered
• θ = number of adsorption sites occupied/number adsorption sites available
• Between 0 and 1

Question 6

What are the Factors Influencing Adsorption?

Answer 6

• Pressure of Gas
• Temperature
• Capacity of the adsorbent
  
  • Surface area of solid
  • Number of available sites on solid
• Chemical nature of adsorbent and solute/adsorbate (affinity)
• Temperature
• pH
• Concentration of solute

Question 7

What is the Adsorption Isotherm?

Answer 7

• Relationship between amount physically adsorbed and pressure or concentration
• Assume a monomolecular layer adsorbed

Question 8

Describe Interface between solid and gas

Answer 8

• Adsorbed molecules restricted in position
• Adsorption decreases as temperature increases