What Does a Catalyst Do in a Chemical Reaction?

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When you use laundry detergent to get rid of a stain on a shirt, you are watching a catalyst in action during a chemical reaction. Detergents have enzymes, which are catalysts that break up dirt and other stains on clothing. Although they help clean people’s favorite outfits, they are not the only examples of powerful catalysts.

TL;DR (Too Long; Didn't Read)

A catalyst accelerates a chemical reaction. The catalyst remains unchanged after the reaction.

The Effect of a Catalyst on a Chemical Reaction

A catalyst affects a chemical reaction by accelerating it. It also offers an alternative way for the reaction to happen that lowers the amount of energy needed. Reactions require activation energy to start, and catalysts can help. However, catalysts survive the reactions unchanged.

Two Ways Catalysts Affect a Chemical Reaction

The two main ways catalysts affect chemical reactions are by creating a way to lower activation energy or by changing how the reaction happens. They can lower the energy of the transition state, so the overall activation energy needed for the reaction decreases, or they can alter the mechanisms of a reaction and thus change the transition state.

Catalysts do their jobs in different ways. One option is for these substances to allow the reactant molecules to break their bonds and form new ones with the catalysts. These bonds are not permanent, so the catalysts can survive the reactions unchanged. Another way catalysts work is by changing the configuration of the reactants and weakening their bonds.

Examples of Catalysts in Chemical Reactions

Two types of catalysts are homogeneous and heterogeneous. Homogeneous catalysts exist in the same phase as the reactants in the chemical reaction. For example, if the reactants are gases, then the catalyst is also a gas. Heterogeneous catalysts are in a different phase than the reactants. For example, the reactants may be solid, but the catalyst is a liquid.

Enzymes are a typical example of a biological catalyst. These proteins can fold in different ways to help reactions by binding reactants. Catalysts can help hydrolyze sucrose or table sugar. Invertase is an enzyme that helps break down sucrose: sucrose + H2O yields glucose + fructose.

Catalytic converters in cars are another common example of how catalysts work. The catalysts inside the converters tend to be precious metals such as platinum or rhodium. Gases enter the converter and come into contact with the catalysts. Then, harmful pollutants react with the metals and become less toxic.


About the Author

Lana Bandoim is a freelance writer and editor. She has a Bachelor of Science degree in biology and chemistry from Butler University. Her work has appeared on Forbes, Yahoo! News, Business Insider, Lifescript, Healthline and many other publications. She has been a judge for the Scholastic Writing Awards from the Alliance for Young Artists & Writers. She has also been nominated for a Best Shortform Science Writing award by the Best Shortform Science Writing Project.