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Peroxide's cool

  1. Feb 21, 2005 #1


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    Been using [tex]H_2 O_2[/tex] to sterilize a wound. I notice that it fizzes.

    1] I presume the bubbles it releases are [tex]O_2[/tex]. i.e. [tex]2 H_2 O_2 > 2H_2 O + O_2[/tex]
    2] I further presume it is the [tex]O_2[/tex] that kills the bacteria.

    And that makes me wonder:
    3] I notice that it only fizzes on my wound - it does not fizz when applied to normal skin (or the container it comes in, or the Q-tip). Although it does fizz when poured into the drain. It seems to zero in on organic material.

    I am guessing this is because:
    - my skin has an oily (i.e. water repellant) coating that the peroxide can't react on/with, or
    - the wound has chemically active components that normal skin will not expose, or
    - the wound has physically reactive components - like the miscroscopic nicks in a champagne glass that serve as bubble nurseries (I forget the name)

    4] Also, why does it not spontaneously revert to water in the bottle? Even over a long time?

  2. jcsd
  3. Feb 21, 2005 #2


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    1.Yes,the reaction u've discribed is incorrect...The correct redox is:

    [tex] H_{2}O_{2}\rightarrow H_{2}O+O [/tex]

    which means the one atom gets reduced and another oxydated...Note that atomic oxygen is the powerful oxydating agent...So not [itex] O_{2} [/itex] kills bateria (it would be ridiculous,why need hydrogen peroxyde,then),but atomic oxygen...

  4. Feb 21, 2005 #3


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  5. Feb 21, 2005 #4


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    Thank you. I don't think I could have gotten a more comprehensive answer if I'd written the question after reading the answer!

    P.S. dexter: you might want to read it too. It specifies pretty much the exact reaction I did:

    H2O2 --> H2O + O2

    (I think your and their answer are ultimately equivalent, you are just concentrating on a discrete intermediate step).
  6. Feb 21, 2005 #5
    no actually your equation isn't balanced making it wrong. It is a two step reaction as oxygen isn't going to stick around in its monatomic form for long but if it was immediately just diatomic then the air would be as good a bacteriocide as hydrogen peroxide.
    Last edited: Feb 21, 2005
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