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AP Chemistry
Catalysts
Things to know:
A catalyst . . .
- Is a substance that increases the rate of the reaction without being consumed.
- Speeds up both the forward and reverse reactions by:
o Making the activation energies lower
o Making the rate constant higher
- Does not yield more product, but yields product more quickly.
- Provides a different mechanism for the reaction to occur (lowering the energy
pathway.
- Consists of two types:
o Homogeneous catalyst – exists in solution with the reaction mixture
o Heterogeneous catalyst
 speeds up a reaction that occurs in a separate phase
 most often a solid interacting with gaseous or liquid reactants
 needs large surface area to be effective
 Example: Metal-catalyzed hydrogenation of hydrocarbons. (fig 15-24
book)