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Conure
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Dry Si+KMnO4=?
Does anyone know the equation for a dry reaction of Si+KMnO4?
The equation below gives a stoich ratio of 7.5 which gives a weak and incomplete reaction. This indicates that there is too much KMnO4.
3 Si + 4 KMnO4 = 3 SiO2 + 4 MnO2 + 2 K2O
Using a ratio of 3 gives a nice firey reaction and using a ratio 1 gives a slower reaction that can melt through steel.
[Edited on 23-4-2023 by Conure]
Fire is good. Fire is life.
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Admagistr
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Quote: Originally posted by Conure  | Does anyone know the equation for a dry reaction of Si+KMnO4?
The equation below gives a stoich ratio of 7.5 which gives a weak and incomplete reaction. This indicates that there is too much KMnO4.
3 Si + 4 KMnO4 = 3 SiO2 + 4 MnO2 + 2 K2O
Using a ratio of 3 gives a nice firey reaction and using a ratio 1 gives a slower reaction that can melt through steel.
[Edited on 23-4-2023 by Conure] |
May be: 4 KMnO4+5Si=K2SiO3+4 MnSiO3+ K2O
[Edited on 23-4-2023 by Admagistr]
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B(a)P
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Can you test the properties of your reaction products?
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Hey Buddy
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If the reaction products are known, you can determine exactly the highest energy possible by using Jains pyrotechnic valence method. It works by
addressing each element in fuel and oxidizer according to the valence number of its final product, post reaction. Then from that, the optimum mixture
can be exactly calculated, for highest possible energy. It's very accurate. It was developed for use in the petroleum industry to analyze fuel
combustion mixtures but works so well it can be applied to anything. Formulations like ANFO and black powder are replicated exactly. I have run patent
pyrotechnic mixtures through the equation and many times the patent ratios they file for are precisely the calculated percentages.
Mn is the tough one, I'm not exactly sure what its final valence would be or I would just calculate it for you. This is probably one where testing the
old fashioned way is best.
Antimony and KMnO4 64%/36% is used as delay mixture in firing trains. I find Si produces a slag easily if that's desirable.
There's also the shaw thermite tables in the thermite thread. Cant recall if KMnO4 is in the tables as oxidizers, it might be in there.
Regardless, pyro valence technique is described in "Chemistry of Pyrotechnics", John Conkling pretty straight forward. I highly recommend. It makes
mixes easy and works with covalent explosives and binder mixtures too. It starts on page 32 on this pdf.
Attachment: Chemistry_of_Pyrotechnics_Conkling.pdf (3.6MB)
This file has been downloaded 353 times
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Conure
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I dont have any lab equipment so it would have to be very simple tests, if you have any ideas. Btw the end products look like black glass. Perhaps
it's SiO2 mixed with MnO2.
Fire is good. Fire is life.
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metalresearcher
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Si 'metal' can easliy be made from mixing finely divided silica sand with Mg powder :
2Mg + SiO2 => Si + 2MgO
48.6 60
Use a 48:60 == 4:5 stoichiometric mixture.
Igniting with a simple small propane torch works. The reaction proceeds rather slowly but gets very hot. The result can be dissolved in aqueous HCl
which dissolves the MgO, leaving black or dark gray Si behind. That can be used to react with KMnO4. Interesting to try it out.
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Laboratory of Liptakov
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Very interesting methode for preparation Silicon. Thanks for sharing....
Silicagel is relatively pure SiO2, it should by works.
[Edited on 24-4-2023 by Laboratory of Liptakov]
Development of primarily - secondary substances CHP (2015) Lithex (2022) Brightelite (2023) Nitrocelite (2024)
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Admagistr
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| Quote: Originally posted by Laboratory of Liptakov | Very interesting methode for preparation Silicon. Thanks for sharing....
Silicagel is relatively pure SiO2, it should by works.
[Edited on 24-4-2023 by Laboratory of Liptakov] |
The production of silicon from SiO2 by reduction of Mg is a very well-known and old procedure, I have a German book from the period of World War II
and it is already described there...It is not a specialty, but rather the silicon obtained in this way is not very pure,it does not matter for the
mentioned purpose...
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Conure
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This is not a thread about extracting silicon you roly-pollies! 
Fire is good. Fire is life.
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Admagistr
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It's a thread about realizing the reaction you filmed on YT and that includes getting silicon powder...Not everyone is going to buy expensive silicon
powder from a semiconductor manufacture,but people want to get silicon as cheaply as possible and preferably by themselves when they are doing
practical chemistry. So don't insult anyone unnecessarily and don't bring emotions into the discussion on the Forum,which will do no good to
anyone.It's counterproductive and will only provoke the same negative reaction in others...
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MadHatter
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Silicon Powder
I bought silicon powder for $9 per pound from my favorite pyrotechnics supplier.
It's -200 mesh and costs less than most other fuels.
https://www.fireworkscookbook.com
[Edited on 2023/4/25 by MadHatter]
From opening of NCIS New Orleans - It goes a BOOM ! BOOM ! BOOM ! MUHAHAHAHAHAHAHA !
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B(a)P
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| Quote: Originally posted by Conure |
I dont have any lab equipment so it would have to be very simple tests, if you have any ideas. Btw the end products look like black glass. Perhaps
it's SiO2 mixed with MnO2. |
You could react it with hydrochloric acid and estimate how much MnO2 is present by observing the evolved chlorine gas. Try taking a small
sample (sub gram) and grinding it finely, then slowly add HCl to your sample if it bubbles and you see a yellow gas then you know you have a decent
quantity of MnO2 in your product. If you have peroxide you could do a similar test with that (add peroxide to a ground sample of your
product), as MnO2 will decompose peroxide into water and oxygen. Try the peroxide test first if you have it, oxygen is obviously a lot
friendlier than chlorine.
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Admagistr
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If the seller doesn't import it from China and possibly checks the purity,it's a perfect source,at least for members from the USA.A few days ago one
of our new members wrote to me on U2U that he bought fake molybdenum oxide MoO3 on Aliexpress...It doesn't melt even at temperatures close to
1200C.I'll have X-ray spectrometry done,I wonder what it really is...
[Edited on 25-4-2023 by Admagistr]
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Conure
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| Quote: Originally posted by B(a)P | | Quote: Originally posted by Conure |
I dont have any lab equipment so it would have to be very simple tests, if you have any ideas. Btw the end products look like black glass. Perhaps
it's SiO2 mixed with MnO2. |
You could react it with hydrochloric acid and estimate how much MnO2 is present by observing the evolved chlorine gas. Try taking a small
sample (sub gram) and grinding it finely, then slowly add HCl to your sample if it bubbles and you see a yellow gas then you know you have a decent
quantity of MnO2 in your product. If you have peroxide you could do a similar test with that (add peroxide to a ground sample of your
product), as MnO2 will decompose peroxide into water and oxygen. Try the peroxide test first if you have it, oxygen is obviously a lot
friendlier than chlorine. |
The only H2O2 I have access to is 12%, would that be enough?
Fire is good. Fire is life.
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Herr Haber
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I have yet to find any "cons" to Si powder. I mostly used it as primer in colored compositions with Parlon as a binder. I found that most composition
using acetone as a solvent are very dense (without pressing) and hard to ignite.
Si + KClO4 is just as good as a Mg ribbon in contact of the composition.
Many other fuels either dont give you the slag you desire when using Si or react to water, solvents or other components in the mixture.
Metallic fuels such as Al, Mg and apparently MgAl can react depending on the condition. Titanium and Zirconium seem less problematic.
I tried BKNO3 bound in NC on top of a composition. Besides the nice flame I've got nothing special to report. Besides , boron has it's own issues with
oxygen.
The issue with metallic fuels is that even though they have superior heat output their reaction products have a low molecular weight and end up in the
air, not in direct contact with the composition as I (wrongly maybe) imagine molten SiO2 used as a primer adhering to the falling star / crossette /
etc.
May I ask OP, why chose KMnO4 as the oxydizer ?
The spirit of adventure was upon me. Having nitric acid and copper, I had only to learn what the words 'act upon' meant. - Ira Remsen
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Conure
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Because I wanted to see how Si and KMnO4 react... This thread is not about pyrotechnics.
[Edited on 26-4-2023 by Conure]
Fire is good. Fire is life.
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Hey Buddy
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| Quote: Originally posted by Herr Haber |
Si + KClO4 is just as good as a Mg ribbon in contact of the composition.
Many other fuels either dont give you the slag you desire when using Si or react to water, solvents or other components in the mixture.
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This is also what I find. Si/KClO4 is very hot and produces slag. If less slag/hotter conditions are needed, I've found TiH2/KClO4 makes a very hot
incendiary with little slag. Id imagine Ti would be similar. It seems to fire out reaction products that ignite anything combustible around, but it
doesnt gather slag at the reaction zone.
Si/CaSO4 from 30-70% Si is apparently also a decent delay composition.
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Texium
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Thread Moved
26-4-2023 at 10:27 |
woelen
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The OP wants to discuss the specific reaction between KMnO4 and Si, let's try to stay close to this subject.
I myself think that the observed reaction strongly depends on the ratio at which KmNo4 and Si are mixed, and I even think that many different
reactions occur at the same time. Solid-solid reactions seldomly are just a single reaction.
The manganese can end up in many different oxidation states, most likely +4 and 0. Maybe +2 and +3 as well. If a large amount of Si is used, then it
may go down to 0.
In order to find plausible reaction equations, just work with pure oxides and Mn, so use K2O, MnO, Mn2O3, MnO2 and SiO2 as reaction products. K2O will
combine with SiO2 to K2SiO3 (silicate), with MnO2 to K2MnO3 (manganite) and with Mn2O3 to KMnO2 or K3MnO3. The mix will be a complicated one.
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Admagistr
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| Quote: Originally posted by woelen | The OP wants to discuss the specific reaction between KMnO4 and Si, let's try to stay close to this subject.
I myself think that the observed reaction strongly depends on the ratio at which KmNo4 and Si are mixed, and I even think that many different
reactions occur at the same time. Solid-solid reactions seldomly are just a single reaction.
The manganese can end up in many different oxidation states, most likely +4 and 0. Maybe +2 and +3 as well. If a large amount of Si is used, then it
may go down to 0.
In order to find plausible reaction equations, just work with pure oxides and Mn, so use K2O, MnO, Mn2O3, MnO2 and SiO2 as reaction products. K2O will
combine with SiO2 to K2SiO3 (silicate), with MnO2 to K2MnO3 (manganite) and with Mn2O3 to KMnO2 or K3MnO3. The mix will be a complicated one.
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Hi Woelen,what do you personally think of the equation I suggested above:
4 KMnO4+5Si=K2SiO3+4 MnSiO3+ K2O
Could this be one of the reaction branches of this reaction?Surely K2MnSiO4 would also be formed if it is stable under the given conditions,that's why
I preferred to write MnSiO3 and K2O separately in the equation,but in practice there will be a lot of products including various manganese
oxides,manganates,...
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Hey Buddy
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| Quote: Originally posted by woelen |
I myself think that the observed reaction strongly depends on the ratio at which KmNo4 and Si are mixed, and I even think that many different
reactions occur at the same time. Solid-solid reactions seldomly are just a single reaction.
The manganese can end up in many different oxidation states, most likely +4 and 0. Maybe +2 and +3 as well. If a large amount of Si is used, then it
may go down to 0.
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This is correct and it is likely there will be parallel reactions going on with one taking the lead depending on how intense the reaction is. --This
is why it's difficult to speculate the valence of Mn with accuracy. I believe you would have to determine this by measuring products to be exact.
--In terms of a narrowing it down, I can only say with certainty that Si itself becomes SiO2 in oxidation under thermitic conditions. With a final
valence of +4. Other materials that share this state of oxidation in the same thermitic conditions are: S, Ti, and Zr. If you cant find a measured
reaction from Si/KMnO4 in literature, you may find a KMnO4 oxidized reaction with one of those other materials. The pathway would likely be analogous
because their final valences are equal.
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B(a)P
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| Quote: Originally posted by Conure | | Quote: Originally posted by B(a)P | | Quote: Originally posted by Conure |
I dont have any lab equipment so it would have to be very simple tests, if you have any ideas. Btw the end products look like black glass. Perhaps
it's SiO2 mixed with MnO2. |
You could react it with hydrochloric acid and estimate how much MnO2 is present by observing the evolved chlorine gas. Try taking a small
sample (sub gram) and grinding it finely, then slowly add HCl to your sample if it bubbles and you see a yellow gas then you know you have a decent
quantity of MnO2 in your product. If you have peroxide you could do a similar test with that (add peroxide to a ground sample of your
product), as MnO2 will decompose peroxide into water and oxygen. Try the peroxide test first if you have it, oxygen is obviously a lot
friendlier than chlorine. |
The only H2O2 I have access to is 12%, would that be enough? |
Yes MnO2 will decompose 12% peroxide.
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woelen
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| Quote: Originally posted by Admagistr |
Hi Woelen,what do you personally think of the equation I suggested above:
4 KMnO4+5Si=K2SiO3+4 MnSiO3+ K2O
Could this be one of the reaction branches of this reaction?Surely K2MnSiO4 would also be formed if it is stable under the given conditions,that's why
I preferred to write MnSiO3 and K2O separately in the equation,but in practice there will be a lot of products including various manganese
oxides,manganates,... |
This could be one of the possible outcomes of the reaction. Whether you get K2MnSiO4 or K2O + MnSiO3 hardly is relevant in this kind of solid-solid
reactions. How clear is the distinction between K2O+MnSiO3 and K2MnSiO4? There may even be different crystal lattices corresponding to the same
empirical formula, depending on the temperature of formation. Really hard to say in this kind of reactions.
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Admagistr
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| Quote: Originally posted by woelen | | Quote: Originally posted by Admagistr |
Hi Woelen,what do you personally think of the equation I suggested above:
4 KMnO4+5Si=K2SiO3+4 MnSiO3+ K2O
Could this be one of the reaction branches of this reaction?Surely K2MnSiO4 would also be formed if it is stable under the given conditions,that's why
I preferred to write MnSiO3 and K2O separately in the equation,but in practice there will be a lot of products including various manganese
oxides,manganates,... |
This could be one of the possible outcomes of the reaction. Whether you get K2MnSiO4 or K2O + MnSiO3 hardly is relevant in this kind of solid-solid
reactions. How clear is the distinction between K2O+MnSiO3 and K2MnSiO4? There may even be different crystal lattices corresponding to the same
empirical formula, depending on the temperature of formation. Really hard to say in this kind of reactions. |
Thanks for the answer.You are right,it makes no sense to distinguish in a solid phase reaction how the K2O is incorporated into the crystalline
lattice of the silicate and whether it is fully or partially incorporated and what the modification of the resulting compound will be.It has no effect
on the equation to find the best ratio of reactants and the K2O will be present anyway...
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clearly_not_atara
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The most vigorous reaction is most likely:
2Si + 4KMnO4 >> 4MnO2 + 2K2SiO3 + O2
Further reduction of MnO2 likely is rather sluggish. Decomposition of KMnO4 in an acidic rxn mixture at high temperatures is very likely to evolve
some oxygen.
[Edited on 04-20-1969 by clearly_not_atara]
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woelen
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I agree that there is a good chance that some oxygen is formed, but this is a loss of energy. Oxygen is quite energetic and I personally think that
among the most energetic reactions one will find the following:
3 Si + 4 KMnO4 --> 4 MnO2 + 2 K2SiO3 + SiO2
At places, where there is no perfect mixing, and some KMnO4 is present without nearby Si, certainly some O2 will be formed, but this loss of O2 makes
the reaction less energetic. If mixing would be really perfect and no O2 would be formed at all, then the reaction would be even more energetic.
[Edited on 1-5-23 by woelen]
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