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Author: Subject: Potassium permangnate gunpowder.
Vikascoder
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[*] posted on 14-3-2012 at 00:10
Potassium permangnate gunpowder.


I read in inorganic chemistry book written by dr O.P Tandon That gunpowder made by using potassium permanganate is more powerful than potassium nitrate . But when i prepare gunpowder in the same way like we make using KNO3 just i substituted KNO3 with KMnO4 then it leaves a residue And is less powerful. So is there any suggestion to improve it.
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weiming1998
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[*] posted on 14-3-2012 at 03:50


One mole of potassium nitrate equates to 79g, while a mole of KMnO4 equates to 158g. If we look at the two decomposition reactions:
2KNO3===>2KNO2+O2
2KMnO4===>K2MnO4+MnO2+O2
A mole of either KNO3 or KMnO4 produces 16 grams of oxygen, but a mole of KMnO4 is twice as much as a mole of KNO3. So, 79 g of KMnO4 will only release 8 grams of oxygen gas.

See the problem here? The residue are the remains of the not properly oxidized charcoal. In order to gain the same non-residue burn as a KNO3 gun powder, you will need to use twice as much KMnO4. So a gunpowder with 75g KNO3, 15g carbon and 10g S will need around 150g of KMnO4 in order to oxidize it completely.

[Edited on 14-3-2012 by weiming1998]
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[*] posted on 14-3-2012 at 06:11


What a big trouble leave KMnO4 gunpowder . I will prefer kno3
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[*] posted on 14-3-2012 at 06:33


Quote: Originally posted by weiming1998  

2KNO3===>2KNO2+O2
2KMnO4===>K2MnO4+MnO2+O2
A mole of either KNO3 or KMnO4 produces 16 grams of oxygen, but a mole of KMnO4 is twice as much as a mole of KNO3. So, 79 g of KMnO4 will only release 8 grams of oxygen gas.


Actually potassium nitrite breaks down at 440.02 °C (temp according to wiki) into what I'm going to guess is 4KNO<sub>2</sub> => 2K<sub>2</sub>O + 2N<sub>2</sub> + O<sub>2</sub>

So the decomp of potassium nitrate as oxidizer is not so cut and dry, some of the nitrite is going to decomp, some isn't. Some of the nitrite is going to decomp post burn, some of the nitrate is going to decomp post burn. I don't know their standard molar enthalapy or their entropy off the top of my head. But I'm going to guess 2KNO<sub>3</sub> => 2KNO<sub>2</sub> + O<sub>2</sub> is favorable over KNO<sub>2</sub> => 2K<sub>2</sub>O + 2N<sub>2</sub> + O<sub>2</sub>




BOLD

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bahamuth
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[*] posted on 14-3-2012 at 16:05


KMNO4 gunpowder is insanely friction sensitive, I have lead pellets embedded in my face as proof...

Also got manganese oxide colored eyes and skin for quite some time after that.

This was from removing a fuse from a lead block dud if anyone wonder where the lead came from...




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[*] posted on 14-3-2012 at 19:49


bahamuth do you know how to make kmno4 gunpowder
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bahamuth
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[*] posted on 15-3-2012 at 00:13


Not really..

Mind you this is nearly 10 years ago and abandoned that way of chemistry after that incident.

But IIRC it burned faster with a higher portion of sulfur but never as fast as regular gunpowder.

I would actually put it in the same category as KClO3/sulfur mixes with regard to friction sensitivity, though the latter sort of detonates while KMnO4 gunpowder just burns.




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[*] posted on 22-3-2012 at 05:11


I made the gunpowder by using potassium chlorate , permanganate,nitrate. I noticed that the most powerful was of chlorate and the tube in which i used to place gunpowder and measure the distance travelled by the metal ball placed in that tube was most travelled by using chlorate , then permanganate then nitrate but in chlorate it was extremely friction sensitive . In permanganate i have to use lot of permanganate to make gunpowder and it was costly compared to both. Nitrate was fine but it needs a long ball milling time as compared to chlorate and permanganate so my final conclusi
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[*] posted on 22-3-2012 at 05:34


Quote: Originally posted by Vikascoder  
I made the gunpowder by using potassium chlorate , permanganate,nitrate. I noticed that the most powerful was of chlorate and the tube in which i used to place gunpowder and measure the distance travelled by the metal ball placed in that tube was most travelled by using chlorate , then permanganate then nitrate but in chlorate it was extremely friction sensitive . In permanganate i have to use lot of permanganate to make gunpowder and it was costly compared to both. Nitrate was fine but it needs a long ball milling time as compared to chlorate and permanganate so my final conclusi


Chlorate is one of the most powerful solid (at STP) oxidizers.It is much more powerful than either permanganates or nitrates and have a much higher oxygen content. Now let's work out how much oxygen is released when you decompose a chlorate. If you used KClO3, then one mole of that is 122g, with an oxygen release of a whopping 48g/mole! Just 40.6g of potassium chlorate is required to release 16g of oxygen gas, unlike 79g for KNO3 and 158g for KMnO4. With twice the oxygen release, you only need half the amount of KClO3 to oxidize the carbon and sulfur completely, compared to standard KNO3 gunpowders.

But that aside, KClO3 gunpowders are extremely dangerous. Apart from their explosive force, the sulfur has the tendency to (very slowly) hydrolyze to trace amounts of H2SO4 according to the equation: 2S+3O2+2H2O===>2H2SO4. Any sulfur you are using to make the gunpowder is most likely to have that impurity. This impurity reacts with the KClO3 to form chloric acid, which will ignite your gunpowder spontaneously! Even if it doesn't ignite it, it can make your gunpowder extremely sensitive, as you noted. Chlorates may be good for metal powder compositions, but don't mix them with sulfur! Use perchlorates, if you have them. They have a even higher oxygen content still and they don't combust when mixed with sulfur.
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