Peroxide
Definition and meaning of Peroxide in chemistry.
A peroxide is a compound that contains two oxygen atoms bonded directly to each other. This oxygen-to-oxygen link is called a peroxide bond. Each oxygen atom in this bond carries an unusual oxidation state of -1, instead of the more common -2.
In more detail
The oxygen-to-oxygen bond in a peroxide is weak compared to most chemical bonds. Because of this, peroxides break apart easily, sometimes with a burst of energy. When they break down, peroxides often release oxygen gas or form reactive fragments called free radicals.
This makes peroxides strong oxidizing agents, meaning they are good at pulling electrons away from other substances. Peroxides can be organic, with carbon groups attached to the oxygen-oxygen bond, or inorganic, like metal peroxides. Industries use peroxides as bleaches, disinfectants, and starter chemicals for making plastics.
A small amount of peroxide can kick off a chain reaction that turns liquid monomers into solid polymer chains. Because peroxides break down when exposed to light, they are usually stored in dark or brown bottles to keep them stable longer. Not every oxygen-containing compound is a peroxide.
Water (H2O) has oxygen bonded to hydrogen, not to another oxygen atom, so it is not a peroxide at all. Some organic peroxides, like benzoyl peroxide, are common ingredients in acne treatments, where they kill skin bacteria by releasing reactive oxygen. Concentrated peroxides can also be dangerously explosive, so chemists store and transport them with extra care.
Even old bottles of certain ether solvents can slowly form dangerous peroxide buildup just from sitting on a shelf exposed to air.
Key facts
| Field | Inorganic Chemistry |
|---|---|
| Functional group | O-O single bond |
| General formula | R-O-O-R |
| Oxidation state | -1 for each oxygen atom |
| Storage | Kept in dark or brown bottles to slow breakdown from light |
| Common example | Hydrogen peroxide, H2O2 |
Hydrogen peroxide (H2O2) is the most familiar peroxide. It is sold in brown bottles as a disinfectant for small cuts. It is also used to lighten or bleach hair, since it breaks down natural pigment through oxidation.
Frequently asked questions
Why are liquid peroxides commonly stored in dark or opaque brown bottles?
Peroxides, especially solutions like hydrogen peroxide, break down into water and oxygen gas when exposed to light, so dark bottles help them stay stable longer.
Is water a type of peroxide?
No. Water has an oxygen atom bonded to two hydrogen atoms, not to another oxygen atom, so it does not have the oxygen-oxygen bond that defines a peroxide.
Why are peroxides useful in making plastics?
Peroxides break down easily into reactive free radicals. A small dose of peroxide can start a chain reaction that links many small monomer molecules into one long polymer chain.
Related terms
Sources & references
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