StevenRS
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Hydrogen Peroxide Explorations
I searched for a thread devoted to H2O2 and it's uses, and I didn't find one, so here goes.
H2O2 has so many uses, from O2 production to a general oxidizer, and it does some strange stuff at times. There is already a thread on concentrating
it, and if this needs to be moved there, then by all means do so.
To start it off, three questions. When I add Sodium Hydroxide to H2O2, I get a momentary white precipitate (NaOH?) and then it dissolves with some
bubbling. I might be neutralizing a stabilizer, and then catalyzing decomposition.
Also, when I add copper sulfate, it makes a brown precip., and I dont know what it is, maybe a complex or oxide?
H2O2 + H2SO4, I get a great, instant copper polish, and upon long exposure to copper, no detectable erosion or colored salt formation occurs, and I am
clueless.
I am a bit new, but I want to learn, so any help is appreciated.
Edit by Chemoleo: Although there are threads on concentrating H2O2, and some applications with certain amines, none deal
with the many possible reactions of H2O2. Let's make this a dedicated thread for this purpose.
[Edited on 14-2-2008 by chemoleo]
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guy
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so many threads on H2O2 search harder
1. hydrogen peroxide decomposes in basic conditions...you're probably not getting precipitate, just fine bubbles
2. copper hydroxide catalyzes decomposition of H2O2 and forms the more stable CuO (brown-black).
3. H2O2 is a very strong oxidizer in acidic media. However, cleaning copper only has to do with H2SO4 dissolving the CuO.
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woelen
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Point (2), the reaction of copper(II) ions with alkaline peroxide solutions, is more complicated than simple formation of CuO. Copper (II) is capable
of forming peroxides and it definitely is possible to make a compound CuO2, which is said to have a reddish appearance. I even have a prep. for copper
peroxide (if you wish, I can lookup the reference for it tonight, when I am at home again). It, however, is not very stable. On storage it slowly
decomposes and after several weeks of storage at room temperature it looses its excess oxygen and normal copper(II)oxide remains behind.
Hydrogen peroxide indeed is a somewhat strange chemical. A really funny thing is that it is capable of oxidizing ferrocyanide to ferricyanide, but it
also is capable of reducing ferricyanide to ferrocyanide. Try adding H2O2 to a solution of potassium ferrocyanide in dilute acid. The solution at once
becomes bright yellow, the iron is oxidized from state +2 to +3. On the other hand, if you add H2O2 to an alkaline solution of potassium ferricyanide,
then this is reduced and oxygen is formed.
Hydrogen peroxide also reduces a permanganate solution (either to MnO2 or Mn(2+)) and it forms strongly colored complexes with a large number of metal
salts in high oxidation states (Ti, V, Cr, Fe, Mo, W, Nb).
With concentrated HCl (30%) and concentrated H2O2 (30%), mixed with each other, I have the impression that I get an oscillating reaction. The mix can
bubble quite strongly, then it calms down, starts bubbling strongly, calms down, etc. During the calm periods, mostly chlorine gas is formed, during
the strong bubbling periods, mainly oxygen is formed. Apparently, H2O2 is sometimes oxidizing the HCl, sometimes it reduces Cl2. When someone else
could look in more detail to this reaction and could comment on this, that would be nice.
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Ephoton
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I would like to ask a question. I was reading through some of this site when I fell over S.C wack's post on looking into the library for info on the
electro production of ozone from sulfuric acid. now ive just gone through quite a large portion of esp@cenet and found little to no info. might be the
way I search but then again it might not. I remember seeing this synth in an old inorganic chem book I have about 600Km from here so looking it up for
the moment is out of the question. I never got around to trying this. does any one have any info on it. I searched here and only found wacked's post
on the search ozone that was relavent. does not help having a user with the title ozone (probably some bolean thingy from the depths of my descreet
math book that will fix that) ozone sulfuric search brought up nothing at all.
I post this here as I dont want to make a new thread for this question but would rather put it in an peroxide thread. after all ozone plus water makes
peroxide.
very interesting how wack says you can get 45% peroxide by just heating lower concentrations to 70 C for extended periods of time. not much use for me
as 50 % is OTC here.
I would think that H2O2 and HCl would make HOCl which is unstable creating Cl2 on decomposition at first. maby 2HOCl --> H2O + Cl2 + O
nascant O + H2O ---> H2O2 then finaly H2O2 + HOCl ---> H2O + HCl + O2
notincing that you need twice the HOCl to produce Cl2 and as it is unstable the more energy the reaction gets in it the less HOCl there is so the
reaction then favours O2. this would be my guess.
[Edited on 12-2-2008 by Ephoton]
e3500 console login: root
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chemrox
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You're probably right. I tried making pirhana glass cleaner mixing HCl and H2O2. Major gaffe! Hadf to exit the premises while the fans took care of
the vapors.
"When you let the dumbasses vote you end up with populism followed by autocracy and getting back is a bitch." Plato (sort of)
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BromicAcid
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Adding sodium hydroxide to hydrogen peroxide (given that they are of a certain strength) results in the precipitation of sodium peroxide hydrate. I
believe there is a thread on making it, using low temps and such but nothing at all unrealistic about it. If you try to dehydrate it though it
decomposes.
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woelen
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Another nice property of hydrogen peroxide is that it shows red chemiluminiscense in some of its reactions.
One particularly good example is simply pouring 30% H2O2 over crushed swimming pool chlorine tablets. Best results are obtained with granules of
Na-DCCA, but TCCA and Ca(ClO)2 also work. The effect must be watched in a dimly lit or even dark room. Use 30% H2O2, the 3% stuff is not sufficiently
strong and then the effect hardly is noticeable. Also, bleach is not sufficiently strong. You really need the strong hydrogen peroxide and the solid
"chlorine" granules
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StevenRS
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In the commercial baquacil brand H2O2, I cannot find an MSDS for it, what else is in it (stabilizers, etc.)?
I thought it might be phosphoric acid, but i have read 2 different stabilizers are usually used.
It would be nice to be able to remove/neutralize them, as they poison catalysts.
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Ephoton
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yummy woelen mix up a heap of hypo and peroxide in vials around the bedroom
as mood light for one of those special moments  hope ya partner doesnt cough
there
guts up and run screaming from the room. very interesting though I will try this I love
stuff that glows.
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16MillionEyes
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| Quote: | [quote
Also, when I add copper sulfate, it makes a brown precip., and I dont know what it is, maybe a complex or oxide? |
You know, a few months back when I first carried out the reaction I was very puzzled. When I first thought of mixing H2O2 and Cu(II) sulfate I
personally didn't think much of it, I reasoned that since copper is in its 2+ oxidation state the peroxide wouldn't be able to oxidize anything there
( Cu(III) certainly not even considered). Also, the solution contained sodium acetate which was one of the reasons I decided to just mix it in a "see
what happens" type of mood. However, when I added it, something did happen and I got a brown precipitate and from this I searched around for clues.
I didn't think anything was actually oxidized but I did considered reduction. I looked up some standard electric potentials for H2O2 in solutions with
water and Cu(II) and found derived this:
Cat 2(Cu2+(aq) + e- --> Cu+ (aq)) ▲E = 0.253V
Ano H2O2(aq) +2H2O --> O2(g) + 2H3O+ + 2e- ▲E = -0.682
----------------------------------------------------------------------------
2Cu2(aq)+ + H202(aq) + 2H2O(l) --> 2Cu+ + O2 +2H3O+ ▲E=0.835 (E = Ecat - Eano)
In other words (granted I didn't make a mistake) the reaction is favorable and goes to the right (you may calculate Keq from here as well but I
didn't). Also, the evolution of gas (typical Cu(II) catalytic decomposition however in this case perhaps the intermediate precipitates) agrees with
this reaction as well.
A bit excited I tried it again but this time with no sodium acetate and just pure Cu(II) sulfate. This time however, the precipitate was sparse and
didn't last very long but evolution of gas was present (in this case just regular catalysis I presume(d)); a few hours later nothing remained but the
blue solution. Since that day I haven't done anything else with respect to this reaction as I have other things to take care of.
Anyhow, I'm still to try this reaction again but with the copper(II) sulfate/acetate solution, hopefully I'll get the very copious brown precipitate
as the first time. What it really is and how the acetate may play a role on the more noticeable precipitate I don't know. I even considered
Cu(I)acetate but I couldn't really find information on this compound although I do know it exists and if I recall correctly is insoluble in water. In
any case, this is a very interesting reaction and if anyone knows more about this (enlighten me!) please let me know.
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chemrox
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I was going to PM Woelen with this question but decided to show my ignorance and ask in the thread. I mixed pirhana solution (H2O2/H2SO4) with some
nearly spent chromic acid and made ozone in the process.
Now I'm truly puzzled. H2O2 and CrVI, CrIII or CrII do not yield O3. Adding h2o2 to K2Cr2O7 made CrII (pretty) at first, lots of heat, then CrVI
with evolution of O2 not O3. That solution poured into water went to CrIII (green).
When I studied this kind of thing it was all about the symmetry groups. I wouldn't know where to start now.
[Edited on 17-2-2008 by chemrox]
[Edited on 17-2-2008 by chemrox]
"When you let the dumbasses vote you end up with populism followed by autocracy and getting back is a bitch." Plato (sort of)
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StevenRS
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I couldn't find this, but I bet this is out there. Would this happen?
SO<sub>2</sub> + H<sub>2</sub>O<sub>2</sub> --> H<sub>2</sub>SO<sub>4</sub>
Or would I end up with an equilibrium between sulfuric acid, peroxysulfuric acid, and dissolved SO<sub>2</sub>?
I use drain cleaner grade usually, but sometimes I need higher purity, and I could just boil the water off from this reaction to get 90+ sulfuric. Of
topic, does anyone know some amazing way to get all the crud out of drain cleaner acid?
[Edited on 26-4-2008 by StevenRS]
[Edited on 26-4-2008 by StevenRS]
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Formatik
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| Quote: | Originally posted by chemrox
I was going to PM Woelen with this question but decided to show my ignorance and ask in the thread. I mixed pirhana solution (H2O2/H2SO4) with some
nearly spent chromic acid and made ozone in the process.
Now I'm truly puzzled. H2O2 and CrVI, CrIII or CrII do not yield O3. Adding h2o2 to K2Cr2O7 made CrII (pretty) at first, lots of heat, then CrVI
with evolution of O2 not O3. That solution poured into water went to CrIII (green). |
Mentioned in Gmelin's Handbook of Inorganic Chemistry is K2Cr2O7 and concd. H2SO4 when warmed together form ozone (one of several chemical ways to
O3), so maybe it's possible to get it from those also.
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DJF90
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There is a thread on cleaning up drain cleaner acid, and it shouldn't be too hard to find. Sulphur dioxide does dissolve in hydrogen peroxide solution
to form sulphuric acid, and that is also covered in another thread. UTFSE
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