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Gas molecules may adhere, or adsorb to a surface in different ways. If the attractive forces between the molecules and surface are largely non-bonding interactions such as van der Waals forces or hydrogen bonds, the process is called physisorption, while if chemical bonds are formed between the molecules and the surface it is called chemisorption.

Physisorption is the basis for many important techniques for the separation and purification of gases, as well as methods for the characterization of porous materials, including the determination of surface areas.

Chemisorption is the basis for most types of heterogeneous catalysis, in which chemical reactions occur readily between adsorbed molecules that would not normally occur in the gas phase or in solution.

This module explores the thermodynamics of adsorption through molecular simulation. The principal focus is on physisorption and its applications, though we will see that many of the same models and concepts are applicable to both types of adsorption.