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copperastic
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Hydrogen peroxide titration
Hello, I just froze some H2O2 and poured the remaining liquid off to get concentrated H2O2. I looked up ways to preform a titration with it and they
say that you need sulfuric acid and potassium permanganate. Im wondering if i could use manganese dioxide (from a battery) to do a titration. Also i
am new to chemistry so if its very complex please try to make it understandable to me.
Thanks ,
Copperastic
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blogfast25
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Quote: Originally posted by copperastic  | Hello, I just froze some H2O2 and poured the remaining liquid off to get concentrated H2O2. I looked up ways to preform a titration with it and they
say that you need sulfuric acid and potassium permanganate. Im wondering if i could use manganese dioxide (from a battery) to do a titration. Also i
am new to chemistry so if its very complex please try to make it understandable to me.
Thanks ,
Copperastic |
I'm not sure whether your idea of concentrating H2O2 would actually work.
But apart from that manganese dioxide is a water insoluble solid and cannot be used as a titrant. Furthermore, battery filler contains at least 30 %
graphite (conductor), as well as other impurities like iron oxide, zinc chloride and ammonium chloride.
KMnO<sub>4</sub> is cheap and easily available from eBay, Amazon etc. Choose a good quality grade, so it can be used without standardising
the titrant solution.
[Edited on 17-3-2014 by blogfast25]
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copperastic
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Oh ok i will probably get some real stuff thanks
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HgDinis25
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The melting point of H2O2 is −0.43 °C, whereas the melting point of water is 0ºC. You can't freeze a solution of H2O2 in order to concentrate
it.
Here you have some good ideas on titration and how to measure the concentration of your H2O2:
http://www.sciencemadness.org/talk/viewthread.php?tid=28354#...
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copperastic
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HgDinis25 i froze the water and the liquid was H2O2.
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HgDinis25
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You can't do that. When freezing a solution, you won't get the highest melting point to freeze first. It isn't as linear as that. And imagening you
actualy could, the melting points are almost the same.
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blogfast25
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Careful with such claims: do you have evidence to back this up? This is a science forum: misinformation provided inadvertently or on purpose is a
cardinal sin.
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copperastic
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http://www.youtube.com/watch?v=5S4JMcb6-n8 this is the video were i got the infromation.
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HgDinis25
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With all due respect, never place too much trust in herbs and "everything natural" channels that claim synteshis of chemcials. From my own experience,
half of that is plain wrong.
At the beginning, he said he froze the liquid without carefull controling of the temperature. Forget about it, the all solution would have froze all
together.
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DraconicAcid
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| Quote: Originally posted by HgDinis25 | | The melting point of H2O2 is −0.43 °C, whereas the melting point of water is 0ºC. You can't freeze a solution of H2O2 in order to concentrate
it. |
That depends on the original concentration of the solution, and where the eutectic mixture is. According to the phase diagram on page 15 of this: http://webserver.dmt.upm.es/~isidoro/bk3/c07sol/Solution%20p... , you can cool a solution of hydrogen peroxide that is less than 50% hydrogen
peroxide by weight and water will crystallize out, leaving a more concentrated solution of hydrogen peroxide, as long as you don't cool it much past
-50 oC.
Trying link again:
http://webserver.dmt.upm.es/~isidoro/bk3/c07sol/Solution%20p...
Weird. If you google for "hydrogen peroxide eutectic", it's the first link that comes up as a pdf.
[Edited on 17-3-2014 by DraconicAcid]
[Edited on 17-3-2014 by DraconicAcid]
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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blogfast25
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DA:
That link doesn't appear to work, can you fix it? Or attach the pdf here? One can't have enough phase diagrams.
I wouldn't let that guy near a bottle of water, never mind a bottle of peroxide. No evidence for concentration of the
H<sub>2</sub>O<sub>2</sub> is provided whatsoever.
[Edited on 17-3-2014 by blogfast25]
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HgDinis25
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The pdf isn't working for me neither. It would, however, be an interesting read, because I've never heard of peroxide concentration this way nor
thought it possible.
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blogfast25
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Ah, the pdf seems to have mysteriously materialised somehow. If cars or other machines were made of IT they'd be death traps.
I'm gonna print off the relevant pages (15 - 16) and have a closer look.
But it appears that DA is entirely correct.
[Edited on 17-3-2014 by blogfast25]
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HgDinis25
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| Quote: Originally posted by blogfast25 | Ah, the pdf seems to have mysteriously materialised somehow. If cars or other machines were made of IT they'd be death traps.
I'm gonna print off the relevant page (15) and have a closer look.
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Still not working here. If you could scan the relevant page, please...
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MrHomeScientist
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If you would have searched on the forum a bit before posting, you would have found this recent discussion on various methods to determine hydrogen
peroxide concentration: http://www.sciencemadness.org/talk/viewthread.php?tid=28354
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copperastic
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MrHomeScientist!! I watch your videos!
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HgDinis25
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I've already posted such a link in this topic, read a little above. Careful when criticizing the newbies, afterall he ended up starting a constructive
discusion on peroxide concentration.
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blogfast25
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What the phase diagram shows is that between 0 C and - 52 C and between 0 w% and about 50 w% H2O2, H2O(s) separates out. By definition it means that
the liquidus is enriched in H2O2.
Going back to the OP's question, a rough idea of that enrichment can be obtained from a mass balance in H2O2. Say you started from 100 g 10 w% H2O2
and froze out 40 g of ice, leaving 60 g of liquidus.
Since as you started with 10 g of pure H2O2 (10 w% of 100 g) and none is either made or destroyed during freezing, you now have 10 g of pure H2O2 in
60 g of liquidus or 10 w% x (100/60) = 16.7 w% H2O2.
[Edited on 17-3-2014 by blogfast25]
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HgDinis25
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Well, if that's true (I don't know the veracity of such phase diagram) then we have a good method to concentrate store bought peroxide. I have done
some digging here, and I haven't seen anyone posting about this sort of method. Must try it out.
Anyway, ReactionFactory youtube channel has a good demonstrative video, about peroxide titration using sulfuric acid and permanganate. OP, you can
check it out here: http://www.youtube.com/watch?v=Irs0-YrE7mA&list=UU8rrF2J...
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blogfast25
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Full pdf attached.
Attachment: Solution properties phase diagrams.pdf (329kB)
This file has been downloaded 841 times
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HgDinis25
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http://www.sciencemadness.org/talk/viewthread.php?tid=16726
Another thread I found, containing some information about the freezing method. It seems that the quantity you get isn't that much but it's worth the
try.
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blogfast25
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35 % isn't hard to get or expensive nowadays.
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HgDinis25
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I used to get it by 6 euro a liter. But suppliers are stopping to sell this sort of products because of almost no salles.
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blogfast25
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| Quote: Originally posted by HgDinis25 |
I used to get it by 6 euro a liter. But suppliers are stopping to sell this sort of products because of almost no salles. |
http://www.ebay.co.uk/sch/i.html?_trksid=p2050601.m570.l1313...
Hmmm... too many 35 % listings to count. No sales? I doubt that very much: where there's supply there's demand.
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HgDinis25
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Yes, online it's easy. I was talking localy, where I live.
http://www.ebay.co.uk/itm/Commercial-Grade-Hydrogen-Peroxide...
Online, this is probalby the best offer out there for people here in Europe.
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