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Author: Subject: H2o2 from sodium persulfate
symboom
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H2o2 from sodium persulfate

making hydrogen peroxide from potassium persulfate
so when it says dont mix with water does it form hydrogen peroxide when mixed with water

Na2S2O8 + 2H2O > 2NaHSO4 + H2O2?
or calcium persulfate and water > H2O2 precipitate calcium sulfate not sure if that works and if persulfate decompose and how fast into h2o2 in water

and if i add not normal water but 3% h2o2 because it already has a stabilizer

one does say hydrolysis of persulfate that is formed
but not saying with what to form h2o2
my guess calcium hydroxide or a little sodium hydroxide since strong bases decompose h2o2
Ca(OH)<solution in 3% h2o2> + sodium persulfate>not sure how the reaction would go

sodium persulfate
Conditions/substances to avoid mixing persulfates with are: moisture, heat, flame, ignition sources, shock, friction, reducing agents, organic material, sodium peroxide, water, aluminum and powdered metals.

Solubility in water 55.6 g/100 ml (20°C) this don't make since
it does not say it decomposes
another source says Decomposes slowly in moist air.

[Edited on 25-4-2011 by symboom]
Mixell
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Well, because its a strong oxidizer, I assume a solution of it would be quite caustic, so thats probably the reason?
ScienceSquirrel
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The reactions of persulphate salts and the reactive species at a given pH are exhaustively described at length in the literature so why not do a Google as a start.
From the Internet you can move on to the available literature.
ScienceSquirrel
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You seem like an idle sod that will do nothing for themself.
I am not going to feed you anymore and I am tempted to shove the spoon up your arsehole
symboom
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all i could find was info about using persulfate and its reactions with organics really did not need the comment I've searched

[Edited on 26-4-2011 by symboom]
ScienceSquirrel
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Sorry about the insult but going to www.netscape.co.uk and typing in 'persulfate chemistry' yields 57,300 results.
On the first few pages there are several references that deal with your questions so in my opinion you have not looked very far at all!
symboom
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wow my searching sucks your right i just searched persulfate then hydrogen peroxide how it is made they did not go into detail (example hydrolysis of formed pyrosulfate which does not tell me much) on exactly got patent site that told me i had to pay to read it. and bunch of msds sheets and a chemical database telling me what it is. but ill try that search terms thank you.

finally found a book THE MANUFACTURE OF CHEMICALS
BY ELECTROLYSIS which helps

The persulphate solution is then heated in an autoclave at
130-140° C. under a pressure of 100 lb. per sq. inch, and
decomposition ensues according to the equation :—
(NH4)2S2O8 + 2H2O = (NH4)2SO4 + H2SO4 + H2O2 .
The temperature is then lowered to 65°., and by sufficiently
lowering the pressure a solution of hydrogen peroxide
distils.

ok now the temperature makes since Melting Point of sodium persulfate 180*C (decomposes)
and potassium persulfate <100 °C decomp.
no that i now know in water it decomposes to h2o2 and sulfuric acid

so this is what i think i get from this persulfates only react with water under pressure i think react sodium carbonate to neutralize the sulfuric acid.
so if i put in an old pressure cooker (that's what an autoclave looks like to me a pressure cooker sounds like it does the same thing and then lined with a materiel resistant to sulfuric acid and hydrogen peroxide mix or a condenser in a pressure cooker i was planing to use 3% hydrogen peroxide because it already has a stabilizer
then well im just thinking outloud

so silver nitrate and potassium persulfate makes silver peroxide
no sure the reaction is all i could find is silver peroxide is precipitate

maybe some thing to that extent to produce h2o2 from the peroxide without heating and dealing with sulfuric acid

[Edited on 26-4-2011 by symboom]
Nitro-esteban
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Does sodium peroxidisulphate react the same way as ammonium peroxidisulphate? I would expect it to react like this:
Na2S2O8 + 2H2O = 2NaHSO4 + H2O2.
woelen

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My personal experience with peroxodisulfate is that it does not react to form H2O2 at all. Actually, it even reacts with H2O2, resulting in formation of oxygen and sulfate, where H2O2 acts are reductor and S2O8(2-) as oxidizer.

Why do I say this?
1) Peroxides show a very sensitive reaction with acidified dichromate. A deep blue peroxo complex, CrO5, is formed, which is detectable at very low concentrations. Nothing like that is formed from dilute dichromate, peroxodisulfate and some acid.
2) Nickel(II) hydroxide does not react with H2O2, it just remains pale green. This compound, however, does react with S2O8(2-), giving a black solid. When H2O2 is added, then this black solid at once is reduced to pale green Ni(OH)2 again and the H2O2 is acting as reductor, producing oxygen.

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weiming1998
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 Quote: Originally posted by woelen My personal experience with peroxodisulfate is that it does not react to form H2O2 at all. Actually, it even reacts with H2O2, resulting in formation of oxygen and sulfate, where H2O2 acts are reductor and S2O8(2-) as oxidizer. Why do I say this? 1) Peroxides show a very sensitive reaction with acidified dichromate. A deep blue peroxo complex, CrO5, is formed, which is detectable at very low concentrations. Nothing like that is formed from dilute dichromate, peroxodisulfate and some acid. 2) Nickel(II) hydroxide does not react with H2O2, it just remains pale green. This compound, however, does react with S2O8(2-), giving a black solid. When H2O2 is added, then this black solid at once is reduced to pale green Ni(OH)2 again and the H2O2 is acting as reductor, producing oxygen.

But a mixture of sodium persulfate and sulfuric acid reacts slowly with solid potassium permanganate, producing bubbles of oxygen and brown, insoluble MnO2. That suggests that a small amount of H2O2 is formed by hydrolysis of the persulfate under strongly acidic conditions.

Or that the persulfate ion directly reduces KMnO4 to MnO2.
woelen

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This is something which may be interesting to investigate further. Try adding a solution of KMnO4 to a solution of Na2S2O8 (or the ammonium salt) in dilute sulphuric acid. If there really is H2O2 in this solution, then the KMnO4 will be completely decolorized, no brown MnO2 will be formed, but (nearly) colorless Mn(2+) ions.

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j_sum1

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Useful resource on persulfates / peroxide

Firstly, I followed woelen's suggested investigation above -- adding acidified permanganate solution to a solution of Na2S2O8. The solution does not decolorise, although it does so in hydrogen peroxide. I conclude that there is no significant presence of peroxide in a straight solution of persulfate (pH=5.9)

Researching, I found the useful paper attached. Hydrogen peroxide may be present if the pH is low enough. However, the system is complex and there are numerous oxidising species present.

Various sources report production of H2O2 from reacting persulfates with steam.
$$2H_{2}O+S_{2}O_{8}^{2–}—>2HSO_{4}^{–}+H_{2}O_{2}$$
I have not yet found a procedure. I may have to experiment for myself.

Attachment: FMC_Peroxygen_Talk_2010-10_Persulfate_Oxidation_and_Reduction_Reactions.pdf (308kB)