First 139 words of the document:
When a solid catalyst is used to increase the rate of a reaction between gases or liquids, the
reaction occurs on the surface of the solid.
The reactants form bonds with atoms on the surface of the catalyst they are adsorbed
onto the surface.
As a result, bonds in the reactant molecule are weakened and break.
New bonds form between the reactants, held close together on the surface, to form the
This in turn weakens the bonds to the catalyst surface and the product molecules are
Reactants get adsorbed onto catalyst surface
Bonds are weakened
New bonds form
Second bond forms, and product diffuses away
from catalyst surface, leaving it free to adsorb