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Author: Subject: Failed distillation of HNO3 from KNO3 ??
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[*] posted on 23-3-2023 at 00:53


Be very, very careful with this reaction gone wrong.
5ml of perchloric acid 70% was added to a blob of vacuum grease while hot(100c ish). From a safe distance
Just to see what the fuss was about.
My ears are ringing just thinking about it.
Shrapnel was fast.
Detonation was delayed and initiated by bumping the table




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[*] posted on 23-3-2023 at 07:28


I did a bunch of small scale tests which ended up leaving me even more confused...

These were done in mg quantities in test tubes, all heated over a bunsen burner to drive the reaction and I did multiple test with varying amounts of added water:

NH4NO3 + H2SO4 + Cu = Lots of NO2 and bubbling

"KNO3" + H2SO4 + Cu = Dense white fumes and slight blueing of mixture

"KClO4" + H2SO4 + Cu = Nothing at all

I tested two different batches of KNO3 from two different sellers and got the same result, the sulfuric acid does not react with it at all and I think the white fumes are just SO2.

I did a burn test with the KClO4 and both samples of KNO3 in 2:1 oxidizer to sugar, all 3 burned with a hot flame with a hint of purple as expected but the KClO4 burned noticeably more vigorous. Also both of my KNO3 samples are clumpy powder and the KClO4 is a free flowing powder which seems about right, so I don't actually think anything was mixed up at this point. Im at a loss... I just wanted to make some nitric acid and have fun ):

[Edited on 3-23-2023 by Gammatron]




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[*] posted on 23-3-2023 at 07:44


Your KNO3 is obviously not KNO3. The question is, what it is actually. It is not NH4NO3, it is not KClO4.

Let's sum up the known properties of this material:

* Sparsely soluble in water
* Produces fuming and foaming with H2SO4, fumes are yellow
* Is an oxidizer, burns vigorously with sugar, flame has a hint of purple


IDK.... Maybe Berthollet's salt (KClO3)?

What do the crystals look like? Are they needle-like or scale-like? Try to recrystallize it in hot water and tell us the shape of the crystals.

[Edited on 23-3-2023 by ave369]




Smells like ammonia....
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[*] posted on 23-3-2023 at 07:59


Definitely not KClO3, that immediately reacts to form HClO3 which is unstable and yields bright yellow ClO2. I will do a recrystallization right now



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[*] posted on 23-3-2023 at 08:44


I will suggest a flame test.
If it is not KClO3 or KClO4 then its not a potassium cation.
Then some basic reactions like showen in these videos.
H2SO4 https://youtu.be/HtCN_iDQdio
Cations part 1 https://youtu.be/F7cSlwKfoHw
Cations part 2 https://youtu.be/VAy76V4THlY
Anions https://youtu.be/GXCTABFPabM

Dont forget. Most them youtubers make it look easy by screwing up off camera




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[*] posted on 23-3-2023 at 08:51


I should note that the white fumes did not evolve until after strong heating. At room temp there's no reaction.

I remembered that I had a small sample of KNO3 recrystalized from stump remover and when I added the acid to that with a piece of copper it started reacting without heating. I'm thinking that the KNO3 I got from the fireworks place all got put into storage because I thought I was well stocked with the stuff I got on ebay which is what I've been using all along.

It seems pretty hydrophobic and it won't even begin to dissolve until the water is near boiling. It recrystalized into a fine sand-like consistency. It is fairly dense and settles out quickly after being disturbed.

Doing a flame test causes it to melt and rapidly decompose into white smoke with almost no residue, didn't notice any color change of the flame.

20230323_124147.jpg - 1.8MB



[Edited on 3-23-2023 by Gammatron]




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[*] posted on 23-3-2023 at 10:43


Definitely not KNO3. I swear, if it's KNO3 then I'm a Chinese pilot. KNO3 forms distinctive long needle-like crystals. Like this

Potassium_nitrate_crystals.jpg - 156kB

The thing about decomposition into white smoke with no residue makes me again think about ammonium. Not nitrate, maybe ammonium perchlorate?

Damn, this thread begins to look like a mystery novel...

Try a standard alkali test for ammonium? Add concentrated NaOH and take a whiff. If it smells like ammonia, then it's an ammonium salt.


[Edited on 23-3-2023 by ave369]




Smells like ammonia....
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[*] posted on 23-3-2023 at 10:57


Quote: Originally posted by ave369  
Not nitrate, maybe ammonium perchlorate?
Probably not, given the solubility characteristics. Though not as soluble as sodium perchlorate, it's still appreciably soluble in water, and it sounds like this stuff isn't.



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[*] posted on 23-3-2023 at 11:41


No reaction with hot NaOH or NaOCl, not sure what other chemicals I have that I can test it with. I guess I could try making flash powder with it since it burns so well with sugar.

Of all the cheap and popular oxidizers, this stuff doesn't seem like it could be any of them. I mean maybe the purple hint in the sugar flame was just in my head cause I wanted to imagine it was there but it burned just like KNO3. Even tho I bought it for making HNO3 I am not so upset since it's still useful for pyrotechnics... I just want to know wtf it is lol




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[*] posted on 23-3-2023 at 11:52


So I made some flash powder 5:3:2 - Ox:Al:S and hit a little pinch of it with a hammer and now my ears are ringing... It made a very bright flash and was about as loud as a 9mm, pretty impressive power actually!

But the mystery grows, as the powder cannot be lit with a flame, it just decomposes and melts.

[Edited on 3-23-2023 by Gammatron]




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[*] posted on 23-3-2023 at 12:24


I guess this significantly narrows down the search. Not all flash powders give very loud report on shock. I think that someone from Energetic Materials subforum could identify the oxidizer. The crystal shape made me think of potassium persulfate (I happen to have a sample on my shelf), solubility matches too, but the decomposition confuses me, potassium persulfate does not decompose with little or no residue.

[Edited on 23-3-2023 by ave369]




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[*] posted on 23-3-2023 at 12:32


Should I start a new thread? Since this went from a failed distillation to figuring out a mystery oxidizer



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[*] posted on 23-3-2023 at 12:33


I think yes.



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[*] posted on 23-3-2023 at 13:55


I’m going to close this thread now to prevent cross-posting, being as the answer to why the distillation didn’t work has been resolved. For future readers, the new thread is here: https://www.sciencemadness.org/whisper/viewthread.php?tid=15...



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23-3-2023 at 13:55
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