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numos
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Storage of Manganese heptoxide
With me recently finding out about the compound Mn2O7, I've been tempted to do several interesting things with it. However has
anyone ever tried to store it, not a few hours, but long term storage, months/years? Is it even possible?
I've put a small sample in an ampule (see images), as that seemed logical, to prevent contact with air/contaminants which may cause dangerous
reactions. I'm keeping the ampule in a small brick box I made outside. I wish to leave it there for a few months and see how it holds out.
My worries: it will spontaneously explode, and the thing is quasi an incendiary device, as if it were to break, it would react with anything
organic... a lot of things are organic 
Also, this is not designed to be practical, Mn2O7 should be prepared right before use... if that. This is more along the lines
of chemical duribility, will it hold out w/o being ruined.
 
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Töilet Plünger
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I wouldn't even THINK about doing this. The chance of disaster is far too high. But brick is the best choice behind smothering it in concrete.
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Chemosynthesis
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I second the above. It has a CAS number, so you could email a manufacturer if you really want to.
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forgottenpassword
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Very nice. How did you prepare/purify it?
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woelen
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What most worries me is that you have ampouled this 
How did you do that? The risk is insane, if the stuff becomes too warm, it explodes and for ampouling this you most likely had to apply a propane
torch flame or something similarly hot to melt the top of the ampoule. I would not have dared trying to ampoule this stuff.
I expect the ampoule to crack after a few days. This stuff is said to slowly decompose, giving MnO2 and O2. Due to pressure buildup I expect the
ampoule to be destroyed soon. If this crack is violent, then the whole lot may explode, it may also be that the crack is not violent but that the
material leaks out slowly. If you have organic material nearby (e.g. insects, hidden in the nice humid and dark little hole where you put the ampoule)
in that case, the material will explode anyway.
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Zyklon-A
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Well if it indeed is safe in the brick "box", then it wouldn't matter if it exploded, ampuleing would be scary, I remember when I ampuled some Mg
shavings. There was some dust that clung to the neck of the ampule. As I melted it, every once in a while, a dust particle started to burn with a
white flash, once a relatively large shaving started to burn, I was scared the whole thing would combust, but it didn't. Manganese Heptoxide would be
much more scary...
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woelen
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Ampouling magnesium would be no problem to me. Magnesium needs oxygen to react and in the small ampoule the magnesium can only burn for an instant,
then all oxygen is used up. I ampouled a flammable and very volatile liquid like acetyl chloride, but this was not really dangerous, albeit
inconvenient. Mn2O7 on the other hand, does not need any external supply of air or anything else, it can explode without apparent reason. Ampouling
this feels to me as if you are ampouling pure nitrolycerin or some other very unstable explosive, and then even worse!
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Fantasma4500
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wait.. you .. molted the top together?!?!?
i was just about to say that it seems that you did it safely, but man.. heating something like Mn2O7 or having a heating source nearby.. risky..
consider yourself and organic next time you have Mn2O7 within reach
however sadly alibabba seems to have failed me for once.. ive seen acetone peroxide, MEKP... FOOD GRADE COPPER AND CD's.. but manganese heptoxide.. no
dice :/
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forgottenpassword
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According to this post: http://www.sciencemadness.org/talk/viewthread.php?tid=24125&... it is very difficult/impossible to detonate. There are videos on youtube of people
reacting it with various chemicals. This one gives a good idea as to its reactivity: http://www.youtube.com/watch?v=shb-kCpidNE
Evidently it is highly reactive, but perhaps the dangers have been exaggerated. A quick search on google scholar showed that there are several reports
of explosions under certain conditions, however.
[Edited on 4-4-2014 by forgottenpassword]
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unionised
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It's never been a good idea to ampoule something which is likely to evolve gas.
At best, in time, you will have a vial full of MnO2 and high pressure oxygen.
Glass pressure vessels tend to fail spectacularly.
I have ampouled ether- just to prove that it can be done.
That was fairly stupid- but the risks were well known and as well controlled as they were ever going to be.
If I still had that ampoule, it would be no more dangerous than ether "properly" stored in a tin. However a glass vial of Mn2O7 is an accident waiting
to happen.
What are you going to do with it?
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numos
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Quote: Originally posted by woelen  | What most worries me is that you have ampouled this
How did you do that? The risk is insane, if the stuff becomes too warm, it explodes and for ampouling this you most likely had to apply a propane
torch flame or something similarly hot to melt the top of the ampoule. I would not have dared trying to ampoule this stuff.
I expect the ampoule to crack after a few days. This stuff is said to slowly decompose, giving MnO2 and O2. Due to pressure buildup I expect the
ampoule to be destroyed soon. If this crack is violent, then the whole lot may explode, it may also be that the crack is not violent but that the
material leaks out slowly. If you have organic material nearby (e.g. insects, hidden in the nice humid and dark little hole where you put the ampoule)
in that case, the material will explode anyway. |
I did use a propane torch... The explosive point is at 50-55oC, so it was vital to keep it under that temp. I used a relatively small amount of it,
(see image) an I kept the ampule in a three prong clamp, submerged in an ice bath. So the Mn2O7 stayed cool, and the clamp held it (giving me two free
hands) and also acted as a heatsink preventing the heat from migrating down.
The decomposition you mention is what I tried to prevent, is there an actual reason? Exposure to air, water, light, ...sound? I know water destroys
it, but the ampule is sealed...
Also the brick box, (I'll post a pic later when I get home), is in my driveway, even if the ampule did break, there is nothing within a 4m vicinity
that burn or spread the fire, it's where I do all my thermite reactions.
I prepared with conc. sulfuric acid and potassium permanganate crystals, an excess of potassium permanganate was used to create a [saturated? not sure
if that's the right word] solution, then using a pipette removed the liquid leaving the remaining crystals behind.
Not sure how to purify it... distillation is definitely out of the question, Mn2O7 is supposed to be a red oily liquid, and
turns green in the presence of sulfuric acid (according to Wikipedia), plus I'm not sure why that purity is even necessary, the green stuff is enough
for most [all?] reactions, and I imagine that the red is significantly more dangerous.
| Quote: Originally posted by Antiswat |
however sadly alibabba seems to have failed me for once.. ive seen acetone peroxide, MEKP... FOOD GRADE COPPER AND CD's.. but manganese heptoxide.. no
dice :/ |
That is unfortunate, probably evidence that it cannot be safely stored, much less shipped.
| Quote: Originally posted by forgottenpassword |
Evidently it is highly reactive, but perhaps the dangers have been exaggerated. A quick search on google scholar showed that there are several reports
of explosions under certain conditions, however.
[Edited on 4-4-2014 by forgottenpassword] |
I agree, it does seem overly exaggerated, however one explosion is all it takes to destroy a life. Still it seems very difficult to detonate, I read
that striking it (I forget where I read this, sorry ) can cause it to detonate,
and I've tried smashing one drop with a hammer, it wouldn't detonate.
I've done all the things I wanted to do with it, this is purely a test to see how well it holds out and if it can be stored.
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The_Davster
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You do not store Mn2O7. It decomposes to ozone and MnO2 after a few days.
Is this even pure stuff? or is it sulfuric and permanganate mixed and ampouled? I hope the latter, because the former would be insane....I have
ampouled primaries, and this strikes me as a worse idea....
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kristofvagyok
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Mn2O7 is not a good option if you want to put it in a tight container like an ampoule. From time to time it will decompose releasing a lot oxygen what
will cause a high internal pressure.
I have prepared some Mn2O7 a few month ago and tried and oxidation with it what almost ignited.... But here is a few experimental result:
It ignites with contact on chloroform, but it is well soluble in carbon tetrachloride giving a pink/purple solution what could be easily used/stored.
If properly sealed it will not decompose as fast if it is in pure form as a liquid.
Another important thing is, that sulfuric acid is NOT soluble in CCl4, so you can get an acid free solution of the heptoxide.
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-Pictures from chemistry, check it out(:
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DraconicAcid
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| Quote: Originally posted by kristofvagyok | | But here is a few experimental result: It ignites with contact on chloroform, but it is well soluble in carbon tetrachloride giving a pink/purple
solution what could be easily used/stored. |
It will also burn dichloromethane.
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Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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quantumcorespacealchemyst
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neutralization of Mn2O7 with NaOH
does Mn2O7 neutralize with NaOH?
I have brown precipitate after slowly adding an excess of NaOH to a solution of Sulfuric acid and KMnO4 which earlier had Mn2O7 in it.
On neutralization, the solution darkened from light yellow to brownish and on standing, the brown precipitate rises to the top of the flask. the
solution also had a little Terbium sulfate, not enough to be the precipitate it seems.
I don't know if it will decompose slowly on standing at slightly under room temperature.
It might be Manganese dioxide though.
[Edited on 26-2-2015 by quantumcorespacealchemyst]
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quantumcorespacealchemyst
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ah, http://woelen.homescience.net/science/chem/solutions/mn.html... thank you woelen
" lower. Aqueous manganese (III) ions have a nice pink/brown color, as is shown on the picture below. When such a solution is added to a solution of
sodium hydroxide, then a brown hydrous precipitate of Mn(OH)3 or MnO(OH) is produced."
or it could be the brown precipitate in "Oxidation state +4" MnO2. seems mostly like the III species.
[Edited on 26-2-2015 by quantumcorespacealchemyst]
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subsecret
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Not a bad experiment to be repeated if you work behind plexiglass with leather welding gloves and very heavy sleeves. Use a face shield the whole
time, but especially when carrying it outside to the brick box. Even better would be to seal the ampoule outside and immediately put it under the
flower pot. An inverted flower pot would be a good way to keep it confined if you want to see what happens. By all means, design a way to break the
ampoule while it is in the pot. Perhaps heat from the bottom while standing a ways back.
@kristofvagyok: Depending on the concentration of the Mn2O7 solution, it may or may not ignite other organic materials. It would be cool to drop this
solution on paper and wait for the CCl4 to evaporate. I think the reaction may be too slow to ignite the paper unless you had a very concentrated
solution which deposited more on the paper.
[Edited on 26-2-2015 by Awesomeness]
Fear is what you get when caution wasn't enough.
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franklyn
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As you enjoy living dangerously , given that ionic compounds are miscible as a melt , I have wondered if
Manganese Heptoxide might solvate Copper Acetylide. It may actually solidify as a co-crystal or form Permanganyl Acetylide. Having zero oxygen balance
, high density , and endothermic character , such a formula will exhibit high detonation velocity and brisance. Placing a drop of Mn2O7 near a small
amount of CuC2 and tipping the substrate to roll the drop into contact seems a good approach to test this idea best tried as cool as practical ~ 10
ºC.
Mn2O7 + CuC2 => {2 MnO3(+) , O(-2)} + {Cu(+2) , C2(-2)} => CuO + (MnO3)2C2
=> 2 MnO + 2 CO2
CuC2
http://www.youtube.com/watch?v=QY9UtFDtClw
Related threads _
http://www.sciencemadness.org/talk/viewthread.php?tid=61173
http://www.sciencemadness.org/talk/viewthread.php?tid=5557
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MrHomeScientist
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Because it wouldn't be a quantumcorespacealchemyst 'experiment' without a random rare or toxic element thrown in for no reason.
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blogfast25
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| Quote: Originally posted by franklyn |
As you enjoy living dangerously , given that ionic compounds are miscible as a melt , I have wondered if
Manganese Heptoxide might solvate Copper Acetylide. |
Manganese heptoxide is unlikely to be ionic in any meaningful sense of the word.
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fluorescence
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Some years ago a Ph.D. Student at our University worked a long time on stabilizing that stuff.
It ended with a test whether he could slowely drive off everything liquid and get a crystalline form.
That thing exploded and since it was on a heatplate it had so much energy that the whole heat plate
was shot through the bench in the fume hood. There was a hole later.... so I wouldn't really want to ampoule that.
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franklyn
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@ blogfast25
I just go by what I read. Reaction (2) indicates it starts with ionic pairs, though after It may exhibit polar covalence.
(2) , MnO3(+) + MnO4(-) => Mn2O7
http://www.nature.com/srep/2013/130911/srep02636/full/srep02...
in pdf
http://yfzhang.sjtu.edu.cn/en/publications/2013/10.pdf
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xfusion44
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What about storage in the freezer? Melting point is at 5.9°C Would that make it less reactive and slow down decomposition?
[Edited on 27-2-2015 by xfusion44]
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Molecular Manipulations
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Probably, but it's a gamble I wouldn't risk. I would not be happy to open my fridge to find a huge mess of broken bottles, and ruined reagents just
for one pissy ampule of a practically uselessly unstable oxidizer.
I can't think of a single good reason to store it, when it can be made so easily on spot, if it's ever needed in the first place.
-The manipulator
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DraconicAcid
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| Quote: Originally posted by franklyn |
As you enjoy living dangerously , given that ionic compounds are miscible as a melt , I have wondered if Manganese Heptoxide might solvate Copper
Acetylide. |
Do you think copper acetylide would be less reactive towards oxidizers than dichloromethane? You'd have a flame on contact.
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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