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TheHomeScientist

Chemistry tip: Concentrated hydrogen peroxide cheaply

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I got a query from a reader today, asking if there was an inexpensive local source for small quantities of concentrated hydrogen peroxide. (HST sells 30 mL--about one fluid ounce--for $5.50 + shipping.) I replied that food-grade (very pure) concentrated hydrogen peroxide is available locally in many places, but usually in gallon or larger containers.

 

There is, however, an easy and inexpensive way to get small amounts of concentrated hydrogen peroxide. Simply purchase a pint bottle of drugstore 3% hydrogen peroxide for a buck or so, pour a little bit out (to leave room for expansion) and then put it in the freezer. After an hour or two, you'll find that most of the water has frozen solid, leaving a liquid that's much more concentrated hydrogen peroxide. (The actual concentration may vary depending on conditions, but the concentration you get should be fine for nearly any experiment that specifies concentrated hydrogen peroxide.)

 

Note that this concentrated form of hydrogen peroxide lacks the stabilizers present in commercial products and so will decompose pretty rapidly over time. Make it up immediately before you need it. Also note that concentrated hydrogen peroxide is an extremely strong oxidizer, so read the MSDS for concentrated hydrogen peroxide on the HST site or elsewhere and follow all safety precautions.

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I asked my dh to read this thread. He holds a phd in chemistry (Northwestern University, 1994) and is currently employed in that industry.

 

He thinks that the cost of $5.50 plus shipping is worth the safety for students in home setting where dealing with understanding material safety data sheets are involved ;)

 

On concentrating H2O2:

 

1) According to the phase diagram I found, it should be possible to concentrate H2O2 up to around 50% by freezing a less concentrated H2O2 / water solution. HOWEVER,

 

2) concentrated H2O2 is *DANGEROUS*. More so the more concentrated it is. It readily damages organic matter, including living tissue, and may do so quickly and violently at higher concentrations (e.g. it may cause the material to ignite). At high concentrations, H2O2 is also chemically unstable, and at high enough concentrations it may explode.

 

3) The easiest thing is to buy concentrated (e.g. 30%) H2O2 to begin with. I would anyway strongly recommend that anyone who does not know exactly what they are doing should avoid such concentrated stuff. Their lives, health, and property would be at grave risk.

 

I could give a bit of detail on what to expect when attempting the concentration-by-freezing technique, but I really don’t want to encourage anyone to try it.

 

hope that helps with a different perspective when doing science at home with our students. Some things are worth the 5.50 plus shipping when seen with the risk.

 

-crystal

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Actually, you can get up to > 60% concentration by freezing in multiple passes. The single-pass method I described typically yields roughly 20% to 25% concentration, which is actually less hazardous than purchased concentrated H2O2 (which is usually 28% for ACS reagent grade or 35% for concentrated food grade).

 

As I said in my original post, concentrated H2O2 is an extremely strong oxidizer and has to be handled very carefully regardless of whether you make it yourself or purchase it.

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2) concentrated H2O2 is *DANGEROUS*. More so the more concentrated it is. It readily damages organic matter, including living tissue, and may do so quickly and violently at higher concentrations (e.g. it may cause the material to ignite). At high concentrations, H2O2 is also chemically unstable, and at high enough concentrations it may explode.

 

 

Some things are worth the 5.50 plus shipping when seen with the risk.

 

 

:confused: Buying it would make it safer? I would presume that if someone is old enough to be doing these chemistry experiments that they would be well versed in chemical safety.

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:confused: Buying it would make it safer? I would presume that if someone is old enough to be doing these chemistry experiments that they would be well versed in chemical safety.

 

I think my dh's and my comments are being misunderstood. Thank you for the opportunity to clarify. I speak my dh's language, but understand how easy it is to not get what he says. :lol:

 

The product safety remains the same either way whether you buy or make it and require careful safety procedures. That's not the issue. Like everyone on this thread has said, it's dangerous stuff.

 

In my dh's opinion, the procedure of making it in the freezer is riskier than the procedure of buying the product, and probably will outweigh the benefits of a few dollars if something went wrong in the freezing procedure.

In other words, the procedure of freezing is not something he'd encourage someone to do even if they were a high school student well versed in chemical safety.

 

It's just his opinion and his way of saying spend the money on the pre made product instead of potential doctor visit on this. and then again, he could be wrong and it isn't that dangerous of a single pass procedure. I'm not willing to risk it. So, look more into the procedure and see if it worth it.

 

mileage will vary.

 

-crystal

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In my dh's opinion, the procedure of making it in the freezer is riskier than the procedure of buying the product, and probably will outweigh the benefits of a few dollars if something went wrong in the freezing procedure.

 

What, specifically, is your husband's concern. Saying "this might be dangerous" is all well and good, but what is the basis of that warning? As everyone agrees, concentrated hydrogen peroxide is hazardous, but that's true regardless of whether you produce it yourself or buy it from a vendor. But the danger is in using the stuff. Merely cooling it is not hazardous. In fact, cold hydrogen peroxide is less reactive and therefore less hazardous than warmer hydrogen peroxide.

 

In my opinion, talking about explosions and burning the house down and doctor visits is fear-mongering. Yes, hydrogen peroxide is hazardous if you mishandle it, but the small amounts we're talking about minimize the risk. Obviously, it's up to every parent to judge the risks they consider acceptable, but you haven't established that the procedure I mentioned is in fact any riskier than using purchased hydrogen peroxide.

 

I'm 58 years old, and I first produced concentrated hydrogen peroxide by this method when I was about 12. I've done it many times since, and never had a problem. I would be very surprised if anyone else who took reasonable care would have a problem. But if you (or your husband) can point out any specific additional risks beyond those we've discussed, I will certainly stop recommending this procedure for people who simply want a quick, cheap way to produce a few mL of concentrated hydrogen peroxide.

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Incidentally, if anyone is worried about getting too high a concentration, simply keep an eye on the 3% hydrogen peroxide as it freezes. Wait until about an eighth of the original volume is still liquid. That liquid is hydrogen peroxide that's concentrated enough for most experiments that call for concentrated hydrogen peroxide, but still enough more dilute than the commercial 28% to 35% stuff that it's less reactive.

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In my opinion, talking about explosions and burning the house down and doctor visits is fear-mongering. Yes, hydrogen peroxide is hazardous if you mishandle it, but the small amounts we're talking about minimize the risk. .

 

Robert,

 

I'll ask him later if you are really concerned about modifying your advice so that "reasonable precautions" to "minimize risk" can be more helpful for others to succeed like you say you have.

 

I am not qualified to help on that. I'm just a homeschooling teacher who has to rely on expert help. I had asked him thinking "is this true and safe as this guy makes it sound and can we do it for the chemistry lab at home?" I was hoping it was true and save a bit of money. kwim?

 

This is me explaining why I posted to other homeschooling parents. Sadly due to the nature of internet forums I'm concerned you have made the procedure sound like it as safe and simple and easy for a child to do as is making ice cubes in a yogurt container. as you said, you have "minimized the risk" but not eliminated it. Like you said, it's not like you are saying to boil the stuff.

 

If I remember, I'll ask him later. But he didn't seem to want to encourage people to try the experiment. He is not the fear mongering type ;)

 

Very respectfully here, I am not fear mongering. I am encouraging people to investigate the procedure that is suggested and get more than one source before trying what sounds like "too good to be true" solution from someone who is relatively new on the forum.

 

Speaking of being new, you've mentioned you are writing a book to be released next year. It was among your first posts. But can't really seem to find an introduction post on you.

Thanks for mentioning your age again. I noticed in other posts you had said you were a teen ager about 45 years ago. I thought that was an interesting way to phrase it :) What is your homeschooling journey?

 

 

Thanks.

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Robert,

 

I'll ask him later if you are really concerned about modifying your advice so that "reasonable precautions" to "minimize risk" can be more helpful for others to succeed like you say you have.

 

I am not qualified to help on that. I'm just a homeschooling teacher who has to rely on expert help. I had asked him thinking "is this true and safe as this guy makes it sound and can we do it for the chemistry lab at home?" I was hoping it was true and save a bit of money. kwim?

 

This is me explaining why I posted to other homeschooling parents. Sadly due to the nature of internet forums I'm concerned you have made the procedure sound like it as safe and simple and easy for a child to do as is making ice cubes in a yogurt container. as you said, you have "minimized the risk" but not eliminated it. Like you said, it's not like you are saying to boil the stuff.

 

If I remember, I'll ask him later. But he didn't seem to want to encourage people to try the experiment. He is not the fear mongering type ;)

 

Very respectfully here, I am not fear mongering. I am encouraging people to investigate the procedure that is suggested and get more than one source before trying what sounds like "too good to be true" solution from someone who is relatively new on the forum.

 

Speaking of being new, you've mentioned you are writing a book to be released next year. It was among your first posts. But can't really seem to find an introduction post on you.

Thanks for mentioning your age again. I noticed in other posts you had said you were a teen ager about 45 years ago. I thought that was an interesting way to phrase it :) What is your homeschooling journey?

 

 

Thanks.

 

Yes, I am curious about your husband's reason for making that statement. Making the concentrated hydrogen peroxide as I described should, if anything, actually be safer than using store-bought concentrated hydrogen peroxide. In fact, hydrogen peroxide is often stored at low temperature exactly because it's more stable and less reactive that way.

 

One can never "eliminate risk". All human endeavor involves risk. If "safety first" was really the controlling factor, nothing would ever be done. No roads or bridges would be built, no discoveries would be made, nothing new would be invented. We'd still be hunting and gathering.

 

Minimizing risks means weighing the benefits against the potential costs, and not just the economic costs. Kids need to learn to respect hazardous chemicals, not to fear them. Most households have more dangerous chemicals in the basement and under the kitchen sink than you'll use doing chemistry experiments. Ask your husband, for example, what he considers the relative risks of a few mL of 25% hydrogen peroxide versus those of solid sodium hydroxide (AKA crystal drain cleaner.) Of course, not all drain cleaners are sodium hydroxide. I have one under my sink right now, purchased at Ace Hardware, that's 97% sulfuric acid.

 

That's not to say that there aren't any chemicals that are justifiably feared. Dimethyl mercury, for example, scares me to death, as it does any sane professional chemist. But it's important to keep risks in perspective. Assuming no one is going to drink the stuff and that everyone wears goggles and gloves, about the worst that's likely to happen with homemade H2O2 is that someone who's careless enough to get it on their skin will get a painful chemical burn. And even that won't happen if you don't delay washing the spill off with tap water.

 

I haven't done an intro post because I'm trying to tread very lightly here. I sell chemistry kits to homeschoolers, and I'm trying to stay within the guidelines of this forum. I've been reading this forum for years, but have just recently started to post.

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But can't really seem to find an introduction post on you.

Thanks for mentioning your age again. I noticed in other posts you had said you were a teen ager about 45 years ago. I thought that was an interesting way to phrase it :) What is your homeschooling journey?

 

 

 

Oh no! I've never ever done an introduction post on this forum! I didn't know that it was a requirement.

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Oh no! I've never ever done an introduction post on this forum! I didn't know that it was a requirement.

 

Jean, It's not a requirement. Some people do it. but it's not a requirement.

 

Like Robert has said, he does sell some stuff and is working hard to stay within the guidelines.

I was just hoping to get to know Robert a bit more with a posting name of The Home Scientist and listing his company name. He says he's read the forum for a long time. so he knows how it can be with people wanting more info.

I tried to find his company website to learn more about him, but the url wasn't working to reach it. I thought, oh, why not just ask out loud? I was honestly trying to make conversation, but you're right Jean.. this is not the general board. my apologies.

 

 

Robert, Again, I'm not fearful of science. Nor am I saying one shouldn't use any household items for science. ;)

When my dh gets home I'll ask him to explain why he was was willing to spend money instead of the less expensive route for this item. It could be just small warnings or a small extra tip to make it as safe as you have experienced since your teen years. and then again, I could be all wrong about it.

 

 

 

-crystal

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There is, however, an easy and inexpensive way to get small amounts of concentrated hydrogen peroxide. Simply purchase a pint bottle of drugstore 3% hydrogen peroxide for a buck or so, ...

 

Note that this concentrated form of hydrogen peroxide lacks the stabilizers present in commercial products and so will decompose pretty rapidly over time. Make it up immediately before you need it. Also note that concentrated hydrogen peroxide is an extremely strong oxidizer, so read the MSDS for concentrated hydrogen peroxide on the HST site or elsewhere and follow all safety precautions.

 

(bolding is mine)

 

...I'm concerned you have made the procedure sound like it as safe and simple and easy for a child to do as is making ice cubes in a yogurt container. as you said, you have "minimized the risk" but not eliminated it.

 

I am encouraging people to investigate the procedure that is suggested and get more than one source before trying what sounds like "too good to be true" solution from someone who is relatively new on the forum.

 

Speaking of being new, you've mentioned you are writing a book to be released next year. It was among your first posts. But can't really seem to find an introduction post on you.

 

Hi Crystal,

 

I can see, with his use of the words "easy" and "simply," why you'd be concerned. But he did go on to make a note, in his first post in this thread, about safety issues. He also mentioned where safety info. could be found. I read his OP earlier today as a very helpful tip, along with responsible mention of cautions. It's up to readers to read his OP carefully and do further research and make decisions themselves. I also see that he has gone on to explain things further as you (rightfully) questioned. He strikes me as very willing to help us home educators, since he is an experienced home scientist.

 

I haven't done an intro post because I'm trying to tread very lightly here. I sell chemistry kits to homeschoolers, and I'm trying to stay within the guidelines of this forum.

 

I've noticed that, and I think you've done very well.

 

so he knows how it can be with people wanting more info.

I tried to find his company website to learn more about him, but the url wasn't working to reach it.

 

Maybe he can help you find his website - I know I've read it before.

 

He is the author of this well-regarded book:

 

http://www.amazon.com/Illustrated-Guide-Home-Chemistry-Experiments/dp/0596514921/ref=sr_1_1?ie=UTF8&qid=1321921509&sr=8-1

 

Check out the reviews on amazon. I read the book and thought it was fantastic.

 

Also, do a search of these forums for info. on his book (search for his name or the book title) - it has been favourably talked about LONG before he ever started posting here.

 

hth

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Minimizing risks means weighing the benefits against the potential costs, and not just the economic costs. Kids need to learn to respect hazardous chemicals, not to fear them.

 

Robert,

We definitely agree on that. I've thought all along we were more on the same page than on different pages or opposing sides. I'm sorry this got more involved than you were planning with sharing a tip. Part of that is not being in person while talking in real life. such is the life on forums. You've said you've read for a long time, so you know how people like to discuss things.

 

In his opinion, buying this hazardous chemical is his preferred route to go toward teaching high school aged students part of that respect for hazardous materials. Some things we just buy instead of make on our own. Your example with the drano is the perfect example of that. Why make it? go buy it and use it properly. Again, it's not about the use of the product.

 

Neither he nor I said the house would blow. The problems in the freezer could be as simple as temperature of the freezer affecting the concentration levels. So, some of is "quality control" when making hazardous chemicals.

 

So with those factors, it outweighs the benefit of "cheap". It's just one science teacher's preference for respecting hazardous chemics combined with some minor quality control issues, and disposal of extra content.

 

Each family will have different balance points in that decision. But don't boil the stuff! then we'll have to talk about rebuilding houses :lol:

 

(ETA: ah, after following Colleen's helpful link, I see that it's a philosophical difference between these 2 scientists. ok... to each their own)

 

-crystal

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(bolding is mine)

 

 

 

Hi Crystal,

 

I can see, with his use of the words "easy" and "simply," why you'd be concerned. But he did go on to make a note, in his first post in this thread, about safety issues. He also mentioned that the safety info. could be read on his website *or elsewhere.*

 

Thanks Colleen. I tried to find his website. and the only thing I could find was a home construction business in Winston Salem. I figured that can't be right site.

 

He isn't hiding his identity over here. I just couldn't find the info.

 

Yes, he mentioned MSDS. and yes "easy" and "simple" set off some cautions in me. thank you for understanding that. It's the nature of forums.

 

I even searched around for "elsewhere" on safety with freezing. just couldn't find the information. I found where he was involved with astronomy organizations, but not his chemistry stuff. I felt like the dumbest google searcher out there. I can usually find stuff. I wanted to know more and couldn't find it :banghead::banghead::banghead:

 

Thank you for the link to the book.

:001_smile:

it was one more thing that I just couldn't find today even searching here.

 

more head bang

 

 

-crystal

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Thanks Colleen. I tried to find his website. and the only thing I could find was a home construction business in Winston Salem. I figured that can't be right site.

 

He isn't hiding his identity over here. I just couldn't find the info.

 

 

 

Yikes! I made a mistake in my post. HST isn't his website, so I changed what I wrote.

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I tried to find his company website to learn more about him, but the url wasn't working to reach it.

 

If you mean the link in his signature, I think that's an e-mail address. I searched for the http://www.thehomescientist.com in the e-mail address and came up with a "coming soon!" message. Maybe he's revamping? Anyway, there is lots of info. out there on the internet about him and his books.

 

ETA: more links

 

http://www.ttgnet.com/journal/

 

http://www.oreillynet.com/pub/au/422

 

http://blog.makezine.com/archive/2008/07/robert-bruce-thompson-on.html

 

 

(tons of great videos here)

 

hth

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If you mean the link in his signature, I think that's an e-mail address. I searched for the http://www.thehomescientist.com in the e-mail address and came up with a "coming soon!" message. Maybe he's revamping? Anyway, there is lots of info. out there on the internet about him and his books.

 

 

I hope others who share his preferences in methods can find it for the safety information he referenced in first post.

 

Different approaches are not wrong.

Without the link to his book, I was not aware that DIY is his passion in this field.

With that in mind, those who share that philosophical approach should enjoy his tips without further trouble from someone like me who has a different approach. If I had been able to find his book and information and seen it was a deeply held value to him to make chemical kit etc as DIY, I would have never said anything on the thread as we don't have same philosophy.

 

in terms of the search and site....

He is either revamping it, or it was part of various glitches on the internet today. I hear there were lots of them. One geek I know was talking to another geek about it.

so, maybe tomorrow those will be all resolved.

 

thanks again for the amazon link.

 

-crystal

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in terms of the search and site....

He is either revamping it, or it was part of various glitches on the internet today. I hear there were lots of them. One geek I know was talking to another geek about it.

so, maybe tomorrow those will be all resolved.

 

I edited (post #18)(I guess while you were typing) again to add some links for you. But I hear you on the differing philosophies.

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We are DIYers here. We do buy a lot of scientific supplies but there are times when need something that we had forgotten to order. These tips are very helpful to someone like me.:001_smile: I also like the science behind a tip like this - why freezing the hydrogen peroxide would make it more concentrated. That leads to a lot of scientific discussion in our house.

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YES!!! These were the sites I had read previously! But I couldn't find them by googling just now.

 

at least I feel better knowing others were struggling finding the sites. I guess my geek friends were right.

I'm telling ya, the search I did this morning had Robert in the construction industry. Not author of DIY chemistry. and definitely not to his kits.

 

Thanks Colleen and Quark for more info.

 

-crystal

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I also like the science behind a tip like this - why freezing the hydrogen peroxide would make it more concentrated. That leads to a lot of scientific discussion in our house.

 

:iagree:

 

I got the book about a year or two ago because someone posted saying it had one of the best recommendations on how to keep a lab notebook.

 

I like the back & forth discussions too. It helps me think through things I may not have considered otherwise.

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Robert,

 

Speaking of being new, you've mentioned you are writing a book to be released next year. It was among your first posts. But can't really seem to find an introduction post on you.

 

 

Thanks.

 

 

I never made an intro post either. But I do know who Robert is. He wrote the oft-recommended Illustrated Guide to Home Chemistry Experiments I am using this year with my boys and one other family.

 

So far it's going really well except that we do labs at the other family's house and they never seem to allow enough time in spite of my endlessly repeating that we need nice long 4-5 hour blocks of time. Being rushed at the end takes away a lot of the fun.

 

I have to say, I am more worried about the gallon jug of 30.45% hydrochloric acid we have for labs and the powdered NaOH (which seems to eat weighing paper and has etched our analytic balance) than about concentrating some H2O2. Actually, we used concentrated sulfuric acid on Saturday as well. However, safety and care around chemicals is part of what I am trying to teach my lab students. (Also, respect for the expensive lab glassware!) Oh, and fire... the boys just love and and all labs involving fire, especially to check for the presence of H2 gas.

 

Anyway, as a matter of perspective, I don't see how making is any more dangerous than buying it or the general hazards of chemistry labs, particularly full scale chemistry labs.

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Crystal (cbollin), thank you and your dh for taking the time to post this safety warning :)! For those of us that are not experienced enough, it is good to have other opinions on this, as well.

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