noun \kə-ˈta-lə-səs\
plural ca·tal·y·ses\-ˌsēz\

Definition of CATALYSIS

:  a modification and especially increase in the rate of a chemical reaction induced by material unchanged chemically at the end of the reaction


Greek katalysis dissolution, from katalyein to dissolve, from kata- + lyein to dissolve, release — more at lose
First Known Use: 1836

Rhymes with CATALYSIS


noun \kə-ˈtal-ə-səs\   (Medical Dictionary)
plural ca·tal·y·ses \-ˌsēz\

Medical Definition of CATALYSIS

: a change and especially increase in the rate of a chemical reaction induced by a catalyst


noun    (Concise Encyclopedia)

Modification (usually acceleration) of a chemical reaction rate by addition of a catalyst, which combines with the reactants but is ultimately regenerated so that its amount remains unchanged and the chemical equilibrium of the conditions of the reaction is not altered. Catalysts reduce the activation energy barrier between reactants and products. When more than one reaction is possible, a catalyst that accelerates only one reaction pathway selectively enhances the creation of its product. Catalysis is inhibited if the reactant or the catalyst is removed or altered by any of several types of agents (inhibitors). Catalysis in a single phase (e.g., the catalyst is dispersed in a liquid solution or gaseous mixture with the reactants) is homogeneous; that in more than one phase (e.g., the reactants are liquids and the catalyst a solid) is heterogeneous. Chemisorption, a type of heterogeneous catalysis, often involves bonding between the catalyst's solid surface and the reactant, changing the nature of the chemisorbed molecules. To make the accessible surface area as large as possible, such catalysts are finely powdered or highly porous solids. Catalysis is essential to the modern chemical industry. See also enzyme.


Next Word in the Dictionary: catalyst
Previous Word in the Dictionary: catalufa
All Words Near: catalysis

Seen & Heard

What made you want to look up catalysis? Please tell us where you read or heard it (including the quote, if possible).