reagent
ree-AY-junt
/riˈeɪ.dʒənt/
A substance or compound added to a system to bring about a chemical reaction or to test whether a reaction occurs.
Differs from a reactant in that a reagent is often added specifically to detect, measure, or trigger a change.
The story behind the word. Coined in the late 18th century by combining re- (back/again) with agent (one who acts). A reagent is an 'interacting substance' designed to react back upon another substance to reveal its identity.
Word relationships
- reactant: A reactant is any starting chemical in a reaction; a reagent is chosen intentionally to test or produce a specific outcome.
- catalyst: A catalyst speeds up a reaction without being consumed; a reagent takes direct part in testing or reaction.
- product: The substance formed at the end of a chemical reaction.
Commonly confused with
- agent: An agent is a general active force; a reagent is specifically a chemical used for testing or reaction.
Word family
- reagents (noun): Plural form referring to chemical testing substances.
Collocations
- chemical reagent
- reagent grade
- limiting reagent
- diagnostic reagent
Example sentences
- "The chemical reagent turned bright purple upon contact with trace amounts of starch." Organic Chemistry
- "Store the test reagent in a dark bottle to prevent degradation from exposure to ambient light." Diagnostic Testing
Memory hook
A REAGENT makes chemicals REACT AGAIN so you can test them. Substance used to test or cause a reaction.
When not to use
Do not use for general inert solvent liquids that do not participate in or trigger testing reactions.
Fun facts
- In chemical manufacturing, 'reagent grade' is a standard purity rating certified for demanding laboratory research.
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