RogueRose
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35% H2O2 still burning after diluting to 3% - what's the deal?
So I needed some H2O2 to clean some things and I only had 35% so I used 12-13 parts DH2O and 1 part H2O2, measured by volume, and placed it in a
bottle, shook it vigerously. I used it a couple times and I noticed some white spots and a decent amount of burning. I then used it maybe 10-15
times without incident and now I just used it and my finger tips are white and burning a lot! It's almost as bad as the 35% in pain and it is just as
bad in the white-ing. I only touched the liquid for a couple seconds before wiping off.
I also had a similar experience when I made a 5% solution so I could mix it with vinegar for peracetic acid and I noticed that it burnt me fairly
badly when just handling the 5%.
Now I have NO problem with 3% (store bought) at all. I could bathe in it if I wanted, lol. I've actually put it in my hair, allowed it to soak in
and dry without incident (this wasn't to lighten hair but for some scalp issue).
I can't figure out what is going on. Can H2O2 of 4 or 5% burn the skin much more than 3%? The only thing I can think of is that the 35% I have is
much stronger than what it is labeled (maybe 50%?), so that would make all my solutions stronger than what I had expected.
The other thing is that i didn't do this by weight, which I know is a mistake. IDK how much more 35% weighs than water, I need to take that into
account next time but I still didn't think it could be so potent.
As a side note, my freezer gets to about -10F and my 35% does not freeze in it so which I think is to be expected or it is close to the freezing
point.
Anyone have any experience with this?
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RawWork
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DH2O? What? Why?
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Sulaiman
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I believe it is the convention;
dH2O = distilled water
ddH2O = double-distilled water
CAUTION : Hobby Chemist, not Professional or even Amateur
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LearnedAmateur
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Try adding some MnO2 catalyst to a bottle containing a specific volume of the original and diluted peroxide. Collect the oxygen in a gas syringe or in
a balloon, which can then be submerged in water to figure out roughly the volume of oxygen given off. Use pV=nRT (n= pV/RT) to calculate the molar
quantity of evolved oxygen, then use those numbers to figure out the liquid concentration. 2 H2O2 -> 2 H2O + O2.
In chemistry, sometimes the solution is the problem.
It’s been a while, but I’m not dead! Updated 7/1/2020. Shout out to Aga, we got along well.
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AJKOER
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The problem may arise from your dilute H2O2 mix acquiring CO2 from the air (per your comment: "I then used it maybe 10-15 times without incident").
This combined with even trace amounts of select transition metal (like cobalt) or, more likely, Fe2+ or Mn2+, from skin/blood/tap water exposure can
make peroxymonocarbonate. The latter with a transition metal can form carbonate radicals, less powerful than the hydroxyl radical, but selective to
certain organics (causing them to breakdown, translation: PAIN).
The presence of NaCl, from sweat, can at times also be catalytic.
Congratulations, your finger is a nice experiment in advanced oxidation processes demonstrating the power of some AOPs.
Reference: See, for example, "Bicarbonate activation of hydrogen peroxide: A new emerging technology for wastewater treatment" by Ali Jawad, Zhuqi
Chen and Guochuan Yin, with a file download activated by this link: www.cjcatal.org/EN/article/downloadArticleFile.do?attachType... .
[Edited on 28-3-2018 by AJKOER]
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Rhodanide
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Yeah, exactly. I was thinking Deuterium-Hydrogen Peroxide DHO2
at first but I then caught my error
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Ozone
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Distilled water. DHO is frequently referred to as "HOD" in NMR-speak.
O3
-Anyone who never made a mistake never tried anything new.
--Albert Einstein
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RogueRose
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sorry about the DH2O confusion, it was distilled water. I've seen it abbrevieated it as I did most of the time on this site as well as a few others,
so I thought this was standard.
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clearly_not_atara
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I've had fingertips turn white from store-bought peroxide, and also had them not turn white. I presume it was the state of my fingers, not the
peroxide. Did you use the peroxide shortly after washing your hands? Removing the sebum will probably make the peroxide reach living tissue faster.
Peroxide/water mixtures show rapid freezing point depression, about 2 C at 3% H2O2. You could test the freezing point of the "35%" peroxide you
started with, probably without noticeable degradation, to determine if it is more concentrated. The first eutectic occurs at about 44% H2O2 with a mp
of about -52 C. The density of 30% H2O2 is 1.11 per Wikipedia and I'm guessing 35% isn't much higher, so if you did overestimate due to density it
wasn't by that much.
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