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Author Topic: Reactions with hydrogen peroxide, sodium hydroxide and various acids.  (Read 24119 times)

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Mixell

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Hello everybody, I need help completing the following equations and a bit more:

The hydrogen peroxide in use was 33%.

H2O2(aq) +2NaOH(s) --> Na2O2 + 2H2O.
If I'm not mistaken this should be the balanced equation, but for some reason some gas appeared when I mixed the two substances together (presumably H2O(g) because the reaction was exothermic, but I'm not sure...).

CuSO4 + H2O2(aq)---> ?
The solution acquired a dirty green color upon reaction.

2Al(s) + 6NaOH---> 2Na3AlO3(aq) + 3H2(g).
Upon dissolving aluminium (aluminium foil was used) in a ~30% solution of sodium hydroxide(might have been more or less, not quite sure) a black solution (much like oil) was formed (I assume the Na3AlO3 should be colorless).
So can anyone fix my equation or tell me what precipitants could have caused the black color in the solution?
Also, will the anion AlO3 (3-, if its an anion at all) form insoluble materials with cations like Cu (2+), Fe (3+),Mn (2+/4+) and Al (3+).

Also, how potassium permanganate (both in solid and in aquatic solution) will react with sulfuric (97%) and nitric acid (68%).

And finally, will hydrogen peroxide react with various acids (HCl,H2SO4,HNO3)?

Thanks in advance for everybody who can help answer my questions =)
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Borek

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Re: Reactions with hydrogen peroxide, sodium hydroxide and various acids.
« Reply #1 on: December 25, 2010, 12:42:29 AM »

Whenever you work with H2O2 and you see a gas, first suspect is oxygen - product of decomposition.

2H2O2 -> 2H2O + O2
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Mixell

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Re: Reactions with hydrogen peroxide, sodium hydroxide and various acids.
« Reply #2 on: December 25, 2010, 03:16:45 AM »

So as I understand some of the H2O2 reacts with the NaOH and some decomposes into H2O and O2?
Also, I discovered that sodium peroxide reacts with water to create sodium hydroxide and hydrogen peroxide, so any sodium peroxide that will be formed will react with the water in the solution and the overall product of the reaction will be just heat and oxygen gas (contrary to what I found in another topic on this forum..)?
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Borek

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Re: Reactions with hydrogen peroxide, sodium hydroxide and various acids.
« Reply #3 on: December 25, 2010, 12:11:49 PM »

Honestly, I don't see how the sodium peroxide can be produced in this reaction - for the reasons you have just named (reaction with water).
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408

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Re: Reactions with hydrogen peroxide, sodium hydroxide and various acids.
« Reply #4 on: December 25, 2010, 03:18:56 PM »

Actually, if you check the  lit (Brauer IIRC) sodium peroxide is easily prepared from 30% or higher aqueous peroxide and conc. NaOH solutions.  I performed this experiment myself and it works well if kept cold.  If it warms up, then there is oxygen produced.

It is a great oxidizer  ;D
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Borek

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Re: Reactions with hydrogen peroxide, sodium hydroxide and various acids.
« Reply #5 on: December 25, 2010, 11:53:02 PM »

Interesting, didn't know. But that's chemistry, no wonder intuition fails :)
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Mixell

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Re: Reactions with hydrogen peroxide, sodium hydroxide and various acids.
« Reply #6 on: December 26, 2010, 03:48:19 AM »

So how exactly can I produce sodium peroxide from sodium hydroxide and hydrogen peroxide (preferably to get the anhydrous form).
P.S. thank you for the help =)
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Re: Reactions with hydrogen peroxide, sodium hydroxide and various acids.
« Reply #7 on: December 26, 2010, 04:57:55 AM »

http://www.sciencemadness.org/talk/viewthread.php?tid=10

Octahydrate
"Ten grams of carbonate-free sodium hydroxide is dissolved in 25 ml of water in a stoppered Erlenmeyer flask and cooled to 15 degrees. Ten grams of a 30 per cent solution of hydrogen peroxide (corresponding to a mol ratio of NaOH:H2O2 = 2.83:1) is added slowly with constant stirring at a rate such that the temperature does not rise above 18 degrees. Sixty milliliters of 95 per cent alcohol (cooled to 15 degrees) is added; the flask is then stoppered and shaken vigorously. The solution is allowed to stand about 1/2 hour, the supernatant liquid is decanted, and the washing is repeated with two 60 ml portions of cold alcohol. The white crystals are filtered with suction on a hardened filter paper and washed with ether. The compound is transferred quickly to a dessicator containing sulfuric acid (not in vacuo) and kept in a cold chest for 10 hours at a temperature not above 15 degrees. The yield is 18 g (92 per cent based on H2O2). The product may be preserved for a limited amount of time in the ice chest."
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ajkoer

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Re: Reactions with hydrogen peroxide, sodium hydroxide and various acids.
« Reply #8 on: April 16, 2011, 10:30:08 AM »

An earlier edition of Watt's Dictionary of Chemistry notes that adding H2O2 to HCl forms HClO:

                                         HCl + H2O2 = H2O + HClO

 But excess H2O2, reduces the HClO to HCl.

                                          HClO + H2O2 = O2 +  HCl + H2O

Another of Watt's books reports that adding H2O2 to chlorine and water produces HClO:

                                           H2O2 + [Cl2 + H2O] =  2 HClO + H2O

However, my knowledge is that HClO is unstable and concentrated solutions quickly oxidize to HCl and HClO3 (Chloric Acid is a very strong oxidizing acid):
                                            3 HClO = 2 HCl + HClO3

This is the predominant reaction although some of the HClO probably simply decomposes:

                                              2 HClO = O2 + 2 HCl

However, in spite of all the references and facts, "HCl/H2O2" is the name given to this common etching solution and I would not be surprised if your professors simply thinks there is no reaction as otherwise, a lot of people using "HCl/H2O2" would actually not know what they are doing. Likewise, H2SO4/H2O2 AND HNO3/H2O2 are etching solutions for which there is commonly believed to be no reaction.

However, it is also known that H2SO3 (HNO2) is oxidized by H2O2 to H2SO4 (HNO3):

                                           H2O2 + SO2 = H2SO4

                                           H2O2 + HNO2 = HNO3 + H2O

« Last Edit: April 16, 2011, 11:25:24 AM by ajkoer »
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