Langmuir Isotherm

Question 1

Define the three main assumption of Langmuir

Answer 1

Three major assumptions:
• Adsorbent surface is 2D array of energetically homogenous sites = all sites equivalent
• Only one molecule is adsorbed on any one site and adsorption saturation occurs at monolayer coverage
• No interactions between adsorbed molecules

Question 2

When is equilibrium reached?

Answer 2

rate of adsorption = rate of desorption

Question 3

How can the heats of adsorption be determined from isotherm data?

Answer 3

• Heat of adsorption determined by van’t hoff isochore

* Isochore = constant surface coverage