Adsorption: Interactive Simulation

This simulation was prepared using Mathematica. Download the free Wolfram player, and then download the simulation CDF file (link given below or click on figure to download). Try to predict the behavior when a parameter changes before using a slider to change that parameter. A screencast below explains how to use this simulation.

Langmuir isotherms are generated for each component in a binary gas-phase mixture of A and B. Vary the heats of adsorption of each component, the temperature, and the ratio of partial pressures with sliders. The molecules compete for adsorption sites but do not interact with each other. Vary the relative number of sites per molecule with a slider to account for larger molecules occupying more surface area than smaller molecules.

Try to answer these questions before determining the answer with the simulation. We suggest that you write down the reasons for your answers.

  1. For mixture of A and B adsorbing on a surface, if the heat of adsorption for molecule B increased while keeping other parameters the same, what happens to the coverage of A molecules?
  2. For mixture of A and B adsorbing on a surface, suppose the heat of adsorption of molecule B is greater than the heat of adsorption of molecule A. What happens to the relative coverage of B to A as the temperature increases?