# What's up with the different grades of H2O2?

**URL:** <https://boards.straightdope.com/t/whats-up-with-the-different-grades-of-h2o2/759725>\
**Category:** Factual Questions\
**Created:** [July 12, 2016, 3:28pm UTC](https://boards.straightdope.com/t/whats-up-with-the-different-grades-of-h2o2/759725 "2016-07-12T15:28:22Z")\
**Posts on this page:** 1\
**Showing post:** 12

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**Author:** ![robby](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/robby/32/11048_2.png) [@robby](https://boards.straightdope.com/u/robby)\
**Post date:** [July 13, 2016, 4:42am UTC](https://boards.straightdope.com/t/whats-up-with-the-different-grades-of-h2o2/759725/12 "2016-07-13T04:42:15Z")

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> [@TriPolar](#):
>
> H2O2 will degrade rapidly without stabilizers added to it. Food grade should be pure H2O2.

Not pure H[sub]2[/sub]O[sub]2[/sub]; water is also present, of course. (To a chemist, the term “pure H[sub]2[/sub]O[sub]2[/sub]” means only that particular chemical species is present, that is 100% H[sub]2[/sub]O[sub]2[/sub].)

“Food grade” hydrogen peroxide is typically sold as 35% H[sub]2[/sub]O[sub]2[/sub], with the remainder consisting of water. A solution of 35% H[sub]2[/sub]O[sub]2[/sub] is still quite concentrated; note that the typical percentage of hydrogen peroxide for antiseptic use is more like 3%.

As others have noted, pure H[sub]2[/sub]O[sub]2[/sub] is exceedingly dangerous. This was discussed in a [thread](http://boards.straightdope.com/sdmb/showthread.php?t=452812) a few years ago, in which I stated:

> [@Why no "pure" hydrogen peroxide?](https://boards.straightdope.com/t/why-no-pure-hydrogen-peroxide/434827/4):
>
> Hydrogen peroxide is a very strong oxidizing agent, and is not very stable. It spontaneously decomposes into water and oxygen, releasing heat in the process. At very high concentrations (\>70%) , the heat released during decomposition can actually vaporize the remaining liquid. Because it spontaneously decomposes, concentrated hydrogen peroxide has to be stored in special vented containers.
> 
> As the concentration increases, it gets progressively more dangerous. High concentrations of hydrogen peroxide spilled on clothing or other combustible materials can cause the material to spontaneously combust. High concentrations spilled on skin causes severe chemical burns.
> 
> If you drank pure hydrogen peroxide, it would kill you, and it wouldn’t be pleasant.

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