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blogfast25
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Quote: Originally posted by Chemistry Alchemist  | | i want manganese metal for some time now, is it possible to add HCl to the KMnO4 = KCl + MnCl2 + Cl2 and then with the KCl and MnCl2 solution, add
aluminum to it to precipitate the manganese? is this a good method to use? |
Again, this doesn't really belong in this thread.
To answer your question:
the reduction reaction 3 Mn2+(aq) + 2 Al(s) === > 3 Mn(s) + 2 Al3+(aq) can indeed proceed. Unfortunately manganese is a very reactive metal and any
Mn formed would immediately be oxidised completely by water, first to Mn(OH)2, which would then in turn be oxidised again (by air oxygen) to MnO2. No
manganese metal can be obtained this way. That's in contrast to for instance copper, which can be obtained that way but copper is far more 'noble'
than manganese...
The correct equation for the reaction you were trying to write is in fact:
KMnO4 + 8 HCl === > KCl + MnCl2 + 5/2 Cl2 + 4 H2O
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Chemistry Alchemist
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Potassium Manganate disporporting
I done the casual reaction of KMnO4 + Break fluid, this Produces small amounts of Potassium Manganate when the potassium Permanganate decomposes due
to the heat, i washed the remains in water to clean the Manganese oxides, and left nice deep green solution of manganate, now, i wanted to dry it to
a powder so i poored it into a evaporating dish and left it in the sun, an hour later i came back and the solution had turned clear with a brown
precipitate, what has happened here? is the brown precipitate dissolved manganese salt being oxidized in the air to form the Insoluble oxide and left
a solution of potassium ____? please explain if possible 
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blogfast25
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| Quote: Originally posted by Chemistry Alchemist | | I done the casual reaction of KMnO4 + Break fluid, this Produces small amounts of Potassium Manganate when the potassium Permanganate decomposes due
to the heat, i washed the remains in water to clean the Manganese oxides, and left nice deep green solution of manganate, now, i wanted to dry it to
a powder so i poored it into a evaporating dish and left it in the sun, an hour later i came back and the solution had turned clear with a brown
precipitate, what has happened here? is the brown precipitate dissolved manganese salt being oxidized in the air to form the Insoluble oxide and left
a solution of potassium ____? please explain if possible |
Manganates (Mn [+VI] or MnO<sub>4</sub><sup>2-</sup> are
inherently unstable, cannot be isolated and on attempting to isolate, disproportionate: Mn (VI) === > Mn (IV) + Mn (II), so brown MnO2
precipitates...
[Edited on 23-9-2011 by blogfast25]
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Chemistry Alchemist
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Thanks what would be the potassium salt?
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blogfast25
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K2MnO4. But as a solid this is almost impossible to synthesize. In solution it's emerald green (depending concentration, obviously...)
[Edited on 23-9-2011 by blogfast25]
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Chemistry Alchemist
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but isnt K2MnO4 a green solution?
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rstar
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| Quote: Originally posted by blogfast25 |
disproportionate: Mn (VI) === > Mn (IV) + Mn (II), so brown MnO2 precipitates...
[Edited on 23-9-2011 by blogfast25] |
They disproportionate like:
Mn(VI) = Mn(IV) + Mn(VII)
3MnO<sub>4</sub><sup>2-</sup> + 2H<sub>2</sub>O = MnO<sub>2</sub> +
2MnO<sub>4</sub><sup>-</sup> + 4OH<sup>-</sup>
"A tidy laboratory means a lazy chemist "
- Jöns Jacob Berzelius
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blogfast25
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| Quote: Originally posted by rstar | They disproportionate like:
Mn(VI) = Mn(IV) + Mn(VII)
3MnO<sub>4</sub><sup>2-</sup> + 2H<sub>2</sub>O = MnO<sub>2</sub> +
2MnO<sub>4</sub><sup>-</sup> + 4OH<sup>-</sup> |
I only once made some K2MnO4 solution and didn't see it form any purple KMnO4.
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rstar
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Your solution might be quite basic, in which green K2MnO4 is stable, but as your solution will become acidic it will gradually change to purple KMnO4.
Try adding some acids
"A tidy laboratory means a lazy chemist "
- Jöns Jacob Berzelius
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blogfast25
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| Quote: Originally posted by rstar | Your solution might be quite basic, in which green K2MnO4 is stable, but as your solution will become acidic it will gradually change to purple KMnO4.
Try adding some acids |
My solution was very alkaline: MnO2 + KOH + KClO3 fusion product, leached. But I haven't got any right now...
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Waffles SS
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This is possible to use air oxygen instead of potassium nitrate in first reaction?I want to use 50% potassium Hydroxide solution and MnO2 .
I decide to enter air oxygen in this boiling solution by air pump.Does it possible?
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blogfast25
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| Quote: Originally posted by Waffles SS | This is possible to use air oxygen instead of potassium nitrate in first reaction?I want to use 50% potassium Hydroxide solution and MnO2 .
I decide to enter air oxygen in this boiling solution by air pump.Does it possible? |
I doubt that Mn (IV) can be oxidised to Mn (VI) in solution by air oxygen, In fact I'm pretty sure it isn't possible. It requires fusion at least, in
which case vigourous aireation might do the trick.
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Waffles SS
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Thanks dear blogfast25,
What about pure oxygen or ozone(O3)?
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blogfast25
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Ozone? Where are you gonna get that from?
Nah, good old fusing of MnO2/KOH with KNO3 or KClO3 does it nicely.
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Waffles SS
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I have a ozone generator(its for swimming pool) 
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AndersHoveland
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I have always found it interesting that ozone oxidizes chlorine, but not carbon tetrachloride.
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DerAlte
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@ Waffles SS
| Quote: | This is possible to use air oxygen instead of potassium nitrate in first reaction?I want to use 50% potassium Hydroxide solution and MnO2 .
I decide to enter air oxygen in this boiling solution by air pump.Does it possible? |
Yes but not 50% solution. Commercial methods sparge air through MnO2/KOH mixtures but they use molten KOH at highish temperatures.
See the article I wrote and posted as http://www.sciencemadness.org/scipics/MnOXY.doc
Page 12ff.
Regards
Der Alte
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Eddygp
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Is it possible to synthesize in a relatively easy way calcium manganate? Or any other alkali earth, whose chemistry is probably the same...
there may be bugs in gfind
[ˌɛdidʒiˈpiː] IPA pronunciation for my Username |
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blogfast25
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If manganate (MnO<sub>4</sub><sup>2-</sup> - Mn [VI] - is
what you mean then no. It's not very stable at all. Heating MnO2 with KOH and a strong oxidiser like chlorate or nitrate yields it but it decays
quickly.
[Edited on 30-4-2012 by blogfast25]
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Eddygp
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Yes. Manganese, technetium and rhenium have always been quite interesting metals (at least to me). Oh, also chromium.
there may be bugs in gfind
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Random
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Has anyone tried preparing calcium permanganate? Maybe it's easier to isolate, anyone knows its properties?
By the way, I have found that sodium permanganate is available as about 30% solution, so it should be definitelly possible to make it.
A very small amount is produced with the reaction of mno2 and bleach with sodium hydroxide. So I am thinking, if we would put MnO2 into hypochlorite
cell and electrolyse it, maybe the continuous slow supply of Cl2 and hypochlorite in a basic solution would over time make a bigger amount of
permanganate.
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plante1999
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| Quote: Originally posted by Random | Has anyone tried preparing calcium permanganate? Maybe it's easier to isolate, anyone knows its properties?
By the way, I have found that sodium permanganate is available as about 30% solution, so it should be definitelly possible to make it.
A very small amount is produced with the reaction of mno2 and bleach with sodium hydroxide. So I am thinking, if we would put MnO2 into hypochlorite
cell and electrolyse it, maybe the continuous slow supply of Cl2 and hypochlorite in a basic solution would over time make a bigger amount of
permanganate. |
You need strong mixing of the MnO2 in the satured solution of sodium chloride, and it work, I already make some with the same process.
I never asked for this.
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Random
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| Quote: Originally posted by plante1999 | | Quote: Originally posted by Random | Has anyone tried preparing calcium permanganate? Maybe it's easier to isolate, anyone knows its properties?
By the way, I have found that sodium permanganate is available as about 30% solution, so it should be definitelly possible to make it.
A very small amount is produced with the reaction of mno2 and bleach with sodium hydroxide. So I am thinking, if we would put MnO2 into hypochlorite
cell and electrolyse it, maybe the continuous slow supply of Cl2 and hypochlorite in a basic solution would over time make a bigger amount of
permanganate. |
You need strong mixing of the MnO2 in the satured solution of sodium chloride, and it work, I already make some with the same process.
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Yeah, I thought stirring would be useful there. What concentration was it? Could it be useful solution for example for oxidation of alcohols?
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plante1999
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I don't remember perfectly but yes it could be used to oxidize alcohols. Reaction with alcohol is fast and exothermic.
I never asked for this.
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Arcuritech
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I noticed that most (if not all) of this thread is about alkali metal permanganates. Does anyone have information on the permanganates of transition
metals, poor metals, etc.? I imagine CuMnO4 would be an amazing oxidizer
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