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What is a Catalyst?

By J.Gunsch
Updated: May 21, 2024

A catalyst is any substance that works to accelerate a chemical reaction. It can be organic, synthetic or metal. The process by which this substance speeds up or slows a reaction is called catalysis.

For any process to occur, energy, known as activation energy is required. Without the help of a catalyst, the amount of energy needed to spark a particular reaction is high. When one is present, the activation energy is lowered, making the reaction happen more efficiently. The substance generally works by either changing the structure of a molecule or by bonding to reactant molecules causing them to combine, react, and release a product or energy. For example, a catalyst is required for oxygen and hydrogen gases to combine and form water.

Without the help of a catalyst, chemical reactions might never occur or take a significantly longer period of time to react. When the chemical reaction occurs, the catalyst itself is not changed and is not part of the end result. Most times, it can be reused over and over in subsequent reactions.

Sometimes instead of accelerating a reaction, a catalyst works to slow a reaction that would normally not occur or occur very slowly. This type of substance is a negative catalyst, which is also referred to as an inhibitor. Inhibitors are important in medicine, where they are critical in treating mental illnesses, high blood pressure, cancer, and myriad other health problems.

A catalyst is used in two types of conditions, either chemical or biochemical. The most common in biochemical reactions are enzymes. Enzymes are highly specialized proteins that accelerate specific chemical reactions. They make life possible. For example, an enzyme found in saliva breaks up food for digestion on contact. With out this, it would take weeks for humans to digest our food.

Catalysts are also important in the laboratory as well as in manufacturing and industry. One of the most famous is the catalytic converter, which helps to prevent automobile emissions and make fuel consumption more efficient. Fertilizers are also catalysts that speed up plant growth.

All The Science is dedicated to providing accurate and trustworthy information. We carefully select reputable sources and employ a rigorous fact-checking process to maintain the highest standards. To learn more about our commitment to accuracy, read our editorial process.
Discussion Comments
By anon998076 — On Apr 07, 2017

True definitions and well explained.

By browncoat — On Nov 10, 2012
@pleonasm - It's interesting how the language changes. I didn't realize a catalyst was an actual scientific term, I'd always heard it in fantasy type novels, where they are talking about a person or object that's going to set events in motion or change the game somehow. Which is kind of the same definition, I suppose.
By KoiwiGal — On Nov 10, 2012

@anon109023 - That's pretty much the reason why catalysts are used. They speed up reactions between chemicals and they sometimes can help a reaction to happen that might not otherwise happen.

For example, they need to use nickel as a catalyst when they are making margarine because it helps to make the vegetable fats react with hydrogen and solidify in that particular way. Nickel isn't in margarine though and it's only there to make the reaction happen or happen faster.

They also use enzymes in a lot of food production as they can speed up processing in various ways, or they can make food react in a particular way that's desirable.

By pleonasm — On Nov 09, 2012

@anon2251 - Technically, a fertilizer isn't a catalyst in the scientific sense, because it doesn't make a chemical reaction faster (unless you are talking about a specific chemical fertilizer and a specific chemical reaction).

It is, however, a catalyst in the popular sense, in that it can accelerate plant growth.

But I'm not quite sure how to answer how you "get it back". If you are talking about fertilizer in gardens, generally you don't get it back. The nutrients go into the plants and then are either harvested, or put back into the soil, depending on what you do with the plants.

By anon273469 — On Jun 07, 2012

Can anyone tell me what pre-treater catalyst is?

By TMarsella — On Feb 23, 2011

Suggested answer to anon 47109 for a 5 word definition of "catalyst."

Definition: Performance generated by outside addition.

By anon127040 — On Nov 14, 2010

mercuric chloride is a catalyst, and as written, most catalysts are reusable, so why isn't this one in particular reusable?

By anon117624 — On Oct 11, 2010

what is a synthetic catalyst? which one is better, synthetic catalyst or natural catalyst?

By anon109023 — On Sep 05, 2010

i can't find why a catalyst is used in industries other than the speed of a reaction. if anyone knows the answer, please help.

By Lightbuld6 — On Aug 16, 2010

lol i hacked this account

By hananali — On Apr 28, 2010

How does catalyst affect the chemical reaction from thermodynamic and kinetic point of view?

By anon70553 — On Mar 15, 2010

an example of a catalyst is electricity or heat.

By anon64873 — On Feb 09, 2010

i need to do a project on catalysis and i can't find a question to base it on. the project is basically a long systematic answer (proof) to the main question in the beginning (aim). i just can't seem to think of a question to do my project on. any ideas please?

By anon59347 — On Jan 07, 2010

catalysts for chemical reactions: seven-letter word.

By anon47109 — On Oct 01, 2009

what is a simple, like five-word definition of a catalyst?

By anon45229 — On Sep 14, 2009

i need help if any one who wants to help me understand it. Answer me please.

By anon29407 — On Apr 01, 2009

think of a catalyst as someone encouraging a person to do something negative. eg. start a fight

By anon25277 — On Jan 26, 2009

describe the uses of catalysts in biochemical systems and industries.

By anon19564 — On Oct 14, 2008

what are the other samples of catalyst?

By anon2251 — On Jul 04, 2007

If a fertilizer is a catalyst, how do you get it back after a reaction?

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