Catalysts: Definition, Types & Examples

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  • 0:01 How Catalysts Work
  • 1:32 Types of Catalysts
  • 3:58 Examples of Catalysts
  • 5:04 Lesson Summary
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Lesson Transcript
Instructor: Danielle Reid

Danielle has taught middle school science and has a doctorate degree in Environmental Health

You realize before barbecuing that the charcoal pieces just won't light. You add lighter fluid and see a huge flame! That lighter fluid is called a catalyst. Continue reading to learn what catalysts are, the different types, and examples.

How Catalysts Work

Do you remember in Super Mario Kart, where you can use a mushroom to get a speed boost, zooming right past your opponents, leaving them in the dust? If you don't know about Super Mario Kart, how about another example? It's an early Monday morning and you keep pressing that snooze button, refusing to get up. All of a sudden, someone bursts into your room and screams 'Wake up!' Can you relate to this? I know I can. In each case, the speed boost and someone yelling to get up are what we call in chemistry, catalysts.


Catalysts by formal definition are substances designed to increase the rate of a reaction. They do this by lowering the energy used when proceeding from reactants to products in a reaction. Think of it this way, catalysts are super boosts that lower the amount of energy a reaction uses to speed up the chemical process. An example of this is shown in the diagram where product A is made. One point to remember is that catalysts are never destroyed or consumed. They swoop in, do their job and swoop right out, going back home without any damage done to them.

Another great reason to have a catalyst, besides adding super boost, is their benefit towards ensuring efficient reactions are performed. In addition to lowering energy, they are very selective in choosing the route a chemical reaction should detour to. This selectivity not only ensures the reaction is completed, but finished in an efficient manner. The reaction used to make product B, shown in the diagram, provides a great illustration of this concept.

Types of Catalysts

Catalysts come in two distinct flavors: homogenous and heterogeneous. Homogenous catalysts mix with reactants in a uniform way. Heterogeneous catalysts mix with reactants in an opposite way. When they are mixed with substances, they reconfigure the substance in such a way to make the reaction efficient. So what does this all mean? Let's look at this in more depth and provide a few examples.

A homogenous catalyst is like a sergeant. It demands order and all rules must be followed. When it is time for a reaction to occur, the sergeant will make sure everyone is lined up ready for battle. Of course, the battle is the reaction where all substances (i.e reactants) must react in a uniform manner to produce the desired product.

A heterogeneous catalyst is quite the opposite. Think of this catalyst as a clown. Not only does it NOT demand order, but actually prefers to mix things up and be different. Before a reaction occurs, the clown will step in and be a guide. It will help everyone move around to his or her desired location rather than dictate each step like the sergeant. Relating to chemistry, the substances (i.e reactants) will reconfigure into a position that is the best fit, prior to reacting. This is all in an effort to ensure the desired product is made.

Now that we have the hard part out of the way, how about we look at a few examples of each catalyst flavor. You may have heard of the word enzyme before. Well not only is an enzyme a great catalyst (probably one of the most famous ones on the market) but is a homogenous catalyst.

Homogenous & Heterogeneous Catalysts

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