# Concentrating Hydrogen Peroxide

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I've seen a lot of information about concentrating both the 3% versions of hydrogen peroxide, and the 30%. I've seen the idea of boiling it (bad idea, due to vapor detonation), and I've seen freezing it (which seems somewhat less explosive) - however can someone explain to me the fine points of freezing hydrogen peroxide, and then removing the concentrated product. If I had the 3% solution, what temperature would it freeze at, and how would I remove the concentrated product, and what concentration would it be. If I use the 30% version (I would prefer this infinitely, as it would give me more peroxide, and I have no problem getting 30% Hydrogen peroxide) - again, the same questions as with the 3% variety.

As a disclaimer, please note that concentrated hydrogen peroxide is corrosive (especially to eyes) and is a very strong oxidizer - it should only be handled with appropriate safety equipment, and under the supervision of someone who is familiar with it's properties.

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"it should only be handled with appropriate safety equipment, and under the supervision of someone who is familiar with it's properties."

So, not by you then.

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... actually, no that is not correct - I work in a school lab with my teacher, who is intimately familiar with it's properties - not to mention I have full gloves, goggle, apron, jump shower and vent hood at my house so even if I wasn't at school, I would still have appropriate equipment

Perhaps we should have complete information before we go making snide responses, eh?

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I've never really tried to concentrate H202—most substances tend to react with it and make it decompose... sorry, I don't know the answer, but don't hesitate to share your results afterwards!

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... actually, no that is not correct - I work in a school lab with my teacher, who is intimately familiar with it's properties - not to mention I have full gloves, goggle, apron, jump shower and vent hood at my house so even if I wasn't at school, I would still have appropriate equipment

Perhaps we should have complete information before we go making snide responses, eh?

It's true that you have nice protective stuff, but none of those mentioned help in case of an explosion.

You're dealing with a potential detonation here, as you mentioned yourself - not just some spilled acid which can ruin your clothes.

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I'm not sure of freezing, however, I do know that adding heat, will only increase the rate of decomposition, will it not, so technically, in boiling it down, it won't concentrate the solution due to the peroxides decomposition, which is rather unstable, at high temperatures, as many have already pointed out. There's good reason why people don't simply boil the peroxide, down to jet fuel concentrations. Because not only is it futile, but you run the risk of injuring yourself and those around you.

Edited by Theophrastus

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It's true that you have nice protective stuff, but none of those mentioned help in case of an explosion.

You're dealing with a potential detonation here, as you mentioned yourself - not just some spilled acid which can ruin your clothes.

Right, but as I said, I won't be heating the solution, as that would lead to an explosion.... as far as I am aware, the peroxide won't detonate unless heated...

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H2O2 has a boiling point of just over 150 deg c. The decomposition occurs more rapidly in alkali, so acid is often added as a stabilizer. Heat does increase decomposition but not as much as you would be evaporating off.

H2O2 can detonate above 70% so unless you boil off more than half your 30% Soln and asuming no H2O2 decomposed during this process (wich it would have) it should be fine. Also you dont have to heat the soln to boiling point you can just increase the heat (70-80) to evaporate off the water.

Alternately you can solidify the water out. H202 has a Freezing point of about half a deg less than H2O therefore as soon as you get any ice crystals forming you filter them out. The remianing soln will be more concentrated. (this process can then be repeated a few times)

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... actually, no that is not correct - I work in a school lab with my teacher, who is intimately familiar with it's properties - not to mention I have full gloves, goggle, apron, jump shower and vent hood at my house so even if I wasn't at school, I would still have appropriate equipment

Perhaps we should have complete information before we go making snide responses, eh?

Since you are asking about its properties I think it's fair to say that you are not familiar with them. Since you also think that you need to heat the stuff to get it to detonate (you don't) and that an apron etc. will do you any good (it won't) then I think my remark is fair comment.

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Since you are asking about its properties I think it's fair to say that you are not familiar with them. Since you also think that you need to heat the stuff to get it to detonate (you don't) and that an apron etc. will do you any good (it won't) then I think my remark is fair comment.

Fair enough - but you're still forgetting that I'm going to be working with my teacher, who is a professional, and would provide the required equipment -

You are right about one thing - I was asking about it's properties, so I would have some idea of how to do this....

Additionally, no MSDS on 90% H2O2 lists it as an explosive - it says

"Product is non-combustible. On decomposition releases

oxygen which may intensify fire. An explosion hazard when mixed with organics at high concentrations." That's why I thought it wouldn't explode by itself unless heated - I knew it could explode when mixed with flammable / combustible material, but if you have other experience, then thank you for the information -

As for your remark, it could have been more polite - wisdom is not a substitute for manners, nor is it an excuse to be rude.

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Mix some manganese dioxide powder into it and then freeze it. That should be fairly safe.

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Additionally, no MSDS on 90% H2O2 lists it as an explosive - it says

"Product is non-combustible. On decomposition releases

oxygen which may intensify fire. An explosion hazard when mixed with organics at high concentrations." That's why I thought it wouldn't explode by itself unless heated - I knew it could explode when mixed with flammable / combustible material, but if you have other experience, then thank you for the information -

AFAIK, it's not a true "explosive" so much as it vigorously and violently decomposes when catalyzed. If you were to put 90% H2O2 in an erlenmeyer containing even traces of copper, silver, manganese, etc. ions, you would readily make a rocket engine of several hundred degree steam and oxygen gas. chances are the erlenmeyer would shatter and scalding steam, peroxide, and glass would go be ejected in all directions, such as into your face.

I don't believe you're working in a school lab at all. I think this is BS to cover your arse.

High concentration H2O2 is made by reduced-pressure fractional distillation in dedicated glass apparatus, IIRC.

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AFAIK, it's not a true "explosive" so much as it vigorously and violently decomposes when catalyzed. If you were to put 90% H2O2 in an erlenmeyer containing even traces of copper, silver, manganese, etc. ions, you would readily make a rocket engine of several hundred degree steam and oxygen gas. chances are the erlenmeyer would shatter and scalding steam, peroxide, and glass would go be ejected in all directions, such as into your face.

I don't believe you're working in a school lab at all. I think this is BS to cover your arse.

High concentration H2O2 is made by reduced-pressure fractional distillation in dedicated glass apparatus, IIRC.

Whether or not you believe me is irrelevant - you're belief or disbelief does not make it true or untrue - however I assure you, I work in a school lab -

Merged post follows:

Consecutive posts merged

I forgot to say - from what everyone tells me, it seems that actually concentrating H2O2 isn't really feasible without specialized equipment, so I think it's safe to say it would be foolish to attempt it - my school is good, but they don't have vacuum distillation apparatus that can handle H2O2 - that and from what you guys say, it's explosive, so I think it would be best to wait on this one -

Anyways, thanks for all of the advice guys -

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Your belief in your teacher's wisdom wouldn't stop the stuff decomposin so I'm glad you have decided against this experiment.

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"it should only be handled with appropriate safety equipment, and under the supervision of someone who is familiar with it's properties."

So, not by you then.

REPLY: John Cuthber is right

Why are you asking the questions you do. It`s an explosive you know. A very unstable and therefore dangerous one.

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Considering it's been more than five months since they asked, your response will probably not be heeded.

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Stick to the subject, please. If you feel uneasy about the intentions of the person making the original post, click the X in the corner of the window.

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you joined these forums just to necromance that?

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"it should only be handled with appropriate safety equipment, and under the supervision of someone who is familiar with it's properties."

So, not by you then.

why is everyone here like this? instead of answering the question they just say "dont do it"

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because if someone goes an burns themselves or loses a finger there is a chance that they will try to blame us for supplying the info to do it. we do not particularly like getting sued.

plus, it always pays to be safe. we are not going to tell some numpty that clearly doesn't know which shoe goes on which foot how to make dangerous substances.

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Disclaimer:

Do not attempt to concentrate any h202 without (a) proper safely materials (eye protection!!) (b)a clear idea of the potential hazards and dangers and how you would react to any of these ©A clear and accurate understanding of the chemistry of the reaction, and (d) The supervision of a responsible adult who will be responsible for your safety and or one who is willing to be sued when you cripple yourself.

To make matters clear, lets begin at the top. Hydrogen peroxide in low concentrations such as those sold at the drug store are not dangerous. It is sold with stabilizing agents that make it difficult to concentrate further. When H2O2 decomposes it looses an oxygen that comes off as a gas. This ability to produce oxygen gives h2o2 its explosive nature. This reaction is also exothermic meaning it give off heat. In small concentrations this change is difficult to measure. At higher concentrations so much heat is given of that it can vaporize the h2o2, creating steam. This reaction is used in some engines.

The fact that stabilizers are present does not mean that the h202 is not dangerous, but that it is only difficult to use. always be aware of the concentrations of your h202 and the safety implications that apply to such concentrations.

Safety concerns come into play when the concentration increases to an extent to make the h2o2 highly corrosive (about 25%), unstable as a lot of heat and oxygen can be produced very quickly, and the combination of extreme heat and oxygen can lead to an explosion if any fuel is present.

To concentrate the h202 the traditional method is to boil it. This is dangerous because it decomposes the h202 rapidly, and makes more oxygen, which could explode.

It was posted before that one if one froze the h202 one would need to filter of the ice as soon as it formed. One only needs to filter of the h202 before all the water is frozen to get more concentrated h202. This method is also fairly ineffective, because of the molecular similarity between the h2o2 and h2o molecules and their similar melting points cause the h202 to become trapped in the water.

Further concentration of h2o2 is made difficult because of common stabilizing agents that prohibit any effective use of concentrated h202

The fact that stabilizers are present does not mean that the h202 is not dangerous, but that it is only difficult to use. always be aware of the concentrations of your h202 and the safety implications that apply to such concentrations.

This said do not attempt to concentrate any h202 without (a) proper safely materials (eye protection!!) (b)a clear idea of the potential hazards and dangers and how you would react to any of these ©A clear and accurate understanding of the chemistry of the reaction, and (d) The supervision of a responsible adult who will be responsible for your safety and or one who is willing to be sued when you cripple yourself.

Merged post follows:

Consecutive posts merged

Disclaimer:

Do not attempt to concentrate any h202 without (a) proper safely materials (eye protection!!) (b)a clear idea of the potential hazards and dangers and how you would react to any of these ©A clear and accurate understanding of the chemistry of the reaction, and (d) The supervision of a responsible adult who will be responsible for your safety and or one who is willing to be sued when you cripple yourself.

To make matters clear, lets begin at the top. Hydrogen peroxide in low concentrations such as those sold at the drug store are not dangerous. It is sold with stabilizing agents that make it difficult to concentrate further. When H2O2 decomposes it looses an oxygen that comes off as a gas. This ability to produce oxygen gives h2o2 its explosive nature. This reaction is also exothermic meaning it give off heat. In small concentrations this change is difficult to measure. At higher concentrations so much heat is given of that it can vaporize the h2o2, creating steam. This reaction is used in some engines.

The fact that stabilizers are present does not mean that the h202 is not dangerous, but that it is only difficult to use. always be aware of the concentrations of your h202 and the safety implications that apply to such concentrations.

Safety concerns come into play when the concentration increases to an extent to make the h2o2 highly corrosive (about 25%), unstable as a lot of heat and oxygen can be produced very quickly, and the combination of extreme heat and oxygen can lead to an explosion if any fuel is present.

To concentrate the h202 the traditional method is to boil it. This is dangerous because it decomposes the h202 rapidly, and makes more oxygen, which could explode.

It was posted before that one if one froze the h202 one would need to filter of the ice as soon as it formed. One only needs to filter of the h202 before all the water is frozen to get more concentrated h202. This method is also fairly ineffective, because of the molecular similarity between the h2o2 and h2o molecules and their similar melting points cause the h202 to become trapped in the water.

Further concentration of h2o2 is made difficult because of common stabilizing agents that prohibit any effective use of concentrated h202

The fact that stabilizers are present does not mean that the h202 is not dangerous, but that it is only difficult to use. always be aware of the concentrations of your h202 and the safety implications that apply to such concentrations.

This said do not attempt to concentrate any h202 without (a) proper safely materials (eye protection!!) (b)a clear idea of the potential hazards and dangers and how you would react to any of these ©A clear and accurate understanding of the chemistry of the reaction, and (d) The supervision of a responsible adult who will be responsible for your safety and or one who is willing to be sued when you cripple yourself.

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I've seen a lot of information about concentrating both the 3% versions of hydrogen peroxide, and the 30%. I've seen the idea of boiling it (bad idea, due to vapor detonation), and I've seen freezing it (which seems somewhat less explosive) - however can someone explain to me the fine points of freezing hydrogen peroxide, and then removing the concentrated product. If I had the 3% solution, what temperature would it freeze at, and how would I remove the concentrated product, and what concentration would it be. If I use the 30% version (I would prefer this infinitely, as it would give me more peroxide, and I have no problem getting 30% Hydrogen peroxide) - again, the same questions as with the 3% variety.

As a disclaimer, please note that concentrated hydrogen peroxide is corrosive (especially to eyes) and is a very strong oxidizer - it should only be handled with appropriate safety equipment, and under the supervision of someone who is familiar with it's properties.

I've distilled hydrogen peroxide many times before (to above 90%)... All you really need is a vacuum pump capable of reaching a few torr in pressure (mine reaches down to 3torr). and a vacuum flask. If you really want no hydrogen peroxide to leave the boiling flask (like if you wanted to distill 3% to 90% you will need a vergrex column about four to five feet tall coming out of the boiling flask. and a water trap/ condenser to condense the h20(g) before it gets sucked into the vacuum pump. And keep the boiling flask in a large water bath so the room temp water warms the boiling flask (because boiling is endothermic of course). Here is a video of one experiment that I did with some of my 90%

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because if someone goes an burns themselves or loses a finger there is a chance that they will try to blame us for supplying the info to do it. we do not particularly like getting sued.

plus, it always pays to be safe. we are not going to tell some numpty that clearly doesn't know which shoe goes on which foot how to make dangerous substances.

but this contributes to the inaccessibility of science

while safety is important it should not make scientists only answer to questions be "you are not a scientist so you are to dumb to...."

perhaps tell him to pursue a collage degree in chem where he might get to do this experiment under a professor's supervision

Whether or not you believe me is irrelevant - you're belief or disbelief does not make it true or untrue - however I assure you, I work in a school lab -

Merged post follows:

Consecutive posts merged

I forgot to say - from what everyone tells me, it seems that actually concentrating H2O2 isn't really feasible without specialized equipment, so I think it's safe to say it would be foolish to attempt it - my school is good, but they don't have vacuum distillation apparatus that can handle H2O2 - that and from what you guys say, it's explosive, so I think it would be best to wait on this one -

Anyways, thanks for all of the advice guys -

so you just decided to get a 0 on the assignment?

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On 4/21/2009 at 1:33 PM, John Cuthber said:

"it should only be handled with appropriate safety equipment, and under the supervision of someone who is familiar with it's properties."

So, not by you then.

I hate people like this. With this attitude, everything we learn will never be passed on and die in a single generation.

Freezing Method:

• very tedious
• cool the 3% Hydrogen Peroxide solution just to the point where ice crystals start to form and filter them off, repeat until desired concentration

Boiling Method:

• not viable due to a high degradation of H2O2 caused by the high temperatures
• however, it can be done so long as you do NOT FULLY BOIL the solution and keep the solution free of dust, agitation, and anything that will increase the rate of degradation
• there should very little if any bubbles coming off, the point here is to just increase the solutions rate of evaporation

Rotovap:

• best yielding method, requires a rather expensive Rotary evaporator and is not suitable for amateur chemists.

BEST METHOD - Vacuum Distilation:

• does require some glassware but the apparatus can be built for ~$50 on ebay • if you are an amateur chemist you most likely will just need to spend$10 on a cheap pump and power supply (will already have the distillation apparatus)
• almost as good a yield as the rotovap
• Pull the best vacuum you can with your equipment or right before the solution is about to boil
• Apply a minimum amount of heat to the distillation flask containing 3% H2O2 (to prevent degradation)
• The concentration of final H2O2 product can be estimated by the volume of water that distilled over
Edited by drew6017

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Two chemist walk into a bar. The first one orders h2o. The second one orders h2o2. The second one dies. LOL

Commercial grade will cut out all the work.

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