Catalyst
High School
Definition
A substance that speeds up a chemical reaction without being used up itself, by lowering the activation energy. Because it is not consumed, a small amount of catalyst can be used repeatedly, as enzymes do in living cells.
Worked examples
\(2\)H\(_2\)O\(_2 \xrightarrow{\)MnO\(_2} 2\)H\(_2\)O\( + \)O\(_2\)
Manganese dioxide speeds up hydrogen peroxide breakdown but is recovered unchanged afterward.
Enzymes like amylase break down thousands of starch molecules per second, then remain ready to catalyze more reactions.
Biological catalysts work repeatedly because they aren't consumed in the reactions they speed up.
Common mistakes
- The catalyst is used up during the reaction → The catalyst is recovered unchanged at the end Catalysts lower activation energy but are not consumed, so the same molecules can be reused.
- Adding a catalyst increases the amount of product formed → A catalyst speeds up the reaction but does not change the equilibrium yield Catalysts make reactions faster, not more complete—they affect rate, not final amounts.
- Catalysts provide energy to the reaction → Catalysts lower the activation energy barrier They create an alternate pathway requiring less energy, rather than supplying energy themselves.
Where you'll use it next
You'll use catalysts when studying reaction rates and equilibrium in chemistry, enzyme function in biology, and industrial processes like the Haber process for ammonia synthesis.
Found in 1 StudyPug lesson
Unlocking the Power of Catalysts in Chemical Reactions
12th Grade12thChemistry 12
Dive into the fascinating world of catalysts and discover how these unsung heroes of chemistry accelerate reactions without being consumed. Learn their impact on industrial processes and biological functions.
See also
Activation energyRate of reactionChemical reactionReaction RatesLe Chatelier's principleDynamic equilibrium
Reviewed by Pat Cheng, M.Ed. — StudyPug Curriculum Lead · Last updated June 6, 2026