http://www.ck12.org Chapter 3. Chemical Interactions
3.28 Catalysts
- Define catalyst.
- Explain how catalysts work.
- Identify the role of catalysts in living things.
The tunnel through this mountain provides a faster route for cars to get to the other side of the mountain. If a
chemical reaction were like a road to the other side of a mountain, a catalyst would be like a tunnel.
What Is a Catalyst?
Acatalystis a substance that increases the rate of a chemical reaction. The presence of a catalyst is one of several
factors that influence the rate of chemical reactions. (Other factors include the temperature, concentration, and
surface area of reactants.) A catalyst isn’t a reactant in the chemical reaction it speeds up. As a result, it isn’t
changed or used up in the reaction, so it can go on to catalyze many more reactions.
Q:How is a catalyst like a tunnel through a mountain?
A:Like a tunnel through a mountain, a catalyst provides a faster pathway for a chemical reaction to occur.
How Catalysts Work
Catalysts interact with reactants so the reaction can occur by an alternate pathway that has a lower activation energy.
Activation energy is the energy needed to start a reaction. When activation energy is lower, more reactant particles
have enough energy to react so the reaction goes faster. Many catalysts work like the one in theFigure3.43. (You
can see an animated version at the following URL.) The catalyst brings the reactants together by temporarily bonding
with them. This makes it easier and quicker for the reactants to react together. Notice how the catalyst is released by
the product molecule at the end of the reaction.