Sciencemadness Discussion Board - Hydrogen peroxide titration

Hydrogen peroxide titration

copperastic - 17-3-2014 at 11:26

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

blogfast25 - 17-3-2014 at 11:34

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.

KMnO4 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]

copperastic - 17-3-2014 at 11:36

Oh ok i will probably get some real stuff thanks

HgDinis25 - 17-3-2014 at 11:37

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#...

copperastic - 17-3-2014 at 11:41

HgDinis25 i froze the water and the liquid was H2O2.

HgDinis25 - 17-3-2014 at 11:45

Quote: Originally posted by copperastic

HgDinis25 i froze the water and the liquid was H2O2.

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.

blogfast25 - 17-3-2014 at 11:50

Quote: Originally posted by copperastic

HgDinis25 i froze the water and the liquid was H2O2.

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.

copperastic - 17-3-2014 at 11:55

http://www.youtube.com/watch?v=5S4JMcb6-n8 this is the video were i got the infromation.

HgDinis25 - 17-3-2014 at 12:01

Quote: Originally posted by copperastic

http://www.youtube.com/watch?v=5S4JMcb6-n8 this is the video were i got the infromation.

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.

DraconicAcid - 17-3-2014 at 12:02

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]

blogfast25 - 17-3-2014 at 12:10

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 H2O2 is provided whatsoever.

[Edited on 17-3-2014 by blogfast25]

HgDinis25 - 17-3-2014 at 12:16

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.

blogfast25 - 17-3-2014 at 12:28

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]

HgDinis25 - 17-3-2014 at 12:31

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.

Still not working here. If you could scan the relevant page, please...

MrHomeScientist - 17-3-2014 at 12:57

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

copperastic - 17-3-2014 at 13:00

MrHomeScientist!! I watch your videos!

HgDinis25 - 17-3-2014 at 13:00

Quote: Originally posted by MrHomeScientist

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

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.

blogfast25 - 17-3-2014 at 13:13

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]

HgDinis25 - 17-3-2014 at 13:16

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...

blogfast25 - 17-3-2014 at 13:17

Quote: Originally posted by HgDinis25

Still not working here. If you could scan the relevant page, please...

Full pdf attached.

Attachment: Solution properties phase diagrams.pdf (329kB)
This file has been downloaded 682 times

HgDinis25 - 17-3-2014 at 13:31

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.

blogfast25 - 17-3-2014 at 14:03

35 % isn't hard to get or expensive nowadays.

HgDinis25 - 17-3-2014 at 14:06

Quote: Originally posted by blogfast25

35 % isn't hard to get or expensive nowadays.

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.

blogfast25 - 17-3-2014 at 14:19

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.

HgDinis25 - 17-3-2014 at 14:21

Quote: Originally posted by blogfast25

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.

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.

ElizabethGreene - 27-3-2014 at 18:53

It is not titration, but you can get an indication of the strength of
the H₂O₂ solution using Manganese
Dioxide, even the impure stuff from dry cell batteries. You're just
trying to determine if the freezing increased the concentration,
right?

To do so, add a specific quantity of your reference solution to a
test tube. Make a small "cigarette" of the manganese dioxide in
paper and gingerly push-pin it to a one-hole rubber stopper.
Connect the stopper to a hose and the hose into the underside of
an inverted water-filled graduated cylinder. When everything is
tight and snug, rap the test tube until the cigarette falls in the
reference solution.

Record the results, clean up, and repeat the experiment with the
"concentrated" solution. Repeat a few more times to establish a
margin of error.

As long as the temperature and atmospheric pressure remain
relatively constant, the runs have consistent quantities of
Manganese Dioxide and you use an excess compared to the
Peroxide then you should get some decent comparative results.

You could Maths the volume of 0₂ produced to get a
more quantitative estimate of the concentration, but remember to
attach a healthy margin of error to that. The limitations here are
numerous, off the top of my head: the reaction produces heat.
Oxygen is soluble in the water in the gas trap. The Gas trap will
contained other dissolved gases, errors will occur in repositioning
the gas tube in the trap, etc.)

I was able to purchase Potassium Permanganate from a Well
Drilling company locally for twice the eBay Price. 2 lbs for
$30.00. It is used to regenerate filters that remove iron from well
water.

Cheers,
Greene

MrHomeScientist - 28-3-2014 at 06:35

Just now getting around to responding to these...

copperastic: Awesome! I'm glad you like my videos

HgDinis25: Doh! I see now that you already posted a link to the thread I mentioned. Your link even goes directly to my own post!

I do apologize if I come off as being harsh sometimes. I shouldn't let outside issues affect my science!