Experimental Chemistry - 2022-04-10
Potassium nitrite is produced by reducing potassium nitrate with calcium formate and its behavior is investigated in five different reactions.
Wow I didn’t even know this method existed! Easy and convenient. Especially when you compare it to the reduction with molten lead. It’s unlikely that we are ever going to test your method because there’s no need to make it but it was a pleasure to watch 😁
Thank you.
The preparation is convenient until it comes to scraping the stuff out of the vessel...
I know only one supplyer from Poland where KNO2 could be bought by private persons... And when a chem is out of stock, it will never be available there again. But what am I talking about - we both know this supplyer well... ;-)
Then there is only NaNO2 left - which is also offered by Biomus. These are the only offers from inside the whole EU without a custom control on shipping - as long as PL stays in the EU...
And it is not possible to replace KNO2 by NaNO2 in every case, i.e. for the detection of cobalt as potassium hexanitrocobalte or copper as potassium copper lead hexanitrite (I think I should make a video about that...).
For German supplyers it's forbidden to sell nitrites via internet und shipping to private persons, while buying them in a local shop, possessing and using them is allowed (the paradox of the ChemVerbV...). And your local shop is my nearest, too - althought it's over 500 km away from me...
I think in other parts of the world it wouldn't be much easier to purchase it...
Also ordering it in PL from outside the EU could be a problem because of the customs...
So the method might help someone who has no other chance to get his hands on this stuff... And Ca(NO3)2 as an educt should also be easier available than KNO3 to start from...
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interesting video - I've seen an old patent that claims good results when graphite is used as a reducing agent in place of formate (and also claims you increase the purity by repeating the process), but I've never actually tried it, and naturally, being 120-odd years old, it doesn't state any quantities
this method certainly a lot less hazardous than using molten metal, that's for sure!
In principle, one can reduce with carbon or sulfur, but then there is a lot of soluble carbonate/sulphate in the product, which has to be crystallized out with an even greater loss.
The advantage of the calcium formate method is that after the end of the reaction, which proceeds fast and almost quantitavely, most of the carbonate is in the form of insoluble and therefore filterable calcium carbonate. The filtered raw product solution therefore already has a comparatively high nitrite content before recrystallization.
In addition, the reaction mixture of nitrate and carbon or sulfur is legally classified as a black powder-like mixture in some countries and is prohibited as such.
You don't get into this legal gray area with formate...
@Experimental Chemistry the patent's author got around this by using calcium hydroxide as one of the reagents, forming insoluble carbonate
but as I said, I've not tried it myself, so I can't vouch for its success
@lefthandedspanner Calcium carbonate and alkali hydroxide (caustification) are formed from calcium hydroxide and alkali carbonate.
The problem is therefore only shifted from the soluble alkali carbonate to the soluble alkali hydroxide, which in turn would also have to be removed from the mixture with the nitrite. Unfortunately, nothing is gained for the purification with the patent.
Non-problematic production of a salt that is usually difficult to obtain or in which the self-synthesis has so far been accompanied by very harmful by-products (lead oxides)...
Do you know any other properties than those shown?
Post them in the comments!
Ya reaction of nitrite with acidified ferrous sulphate to give brown solution.
@Akhil the Chemist Yes, I know, but in my nice transparent rack there is only space for five test tubes - and those five typical reactions are my favorite ones... 😎
Time for me to set up a Patreon account, perhaps I can buy bigger and better presentation material then... 😉
thats very interesting and doable
adding ethanol into HCl then adding nitrite would show an impressive run-off reaction
H2SO4 + FeSO4 is also used to test for nitrites as it forms a brown precipitate
Thanks very much!
The reaction with ferrous ions is indeed well known, has been proposed here several times, and deserves a place in the list of typical reactions. Unfortunately, my transparent test tube rack only has 5 places - so I had to make a choice... ;-)
Reaction with ethanol: yes, it's known, but I'm not a fan of alkyl nitrites - I'm always a bit afraid of sudden severe headaches (I'm a migraine patient). If anything, you would definitely have to do the experiment outside or under a fume hood...
@Experimental Chemistry migraine huh, cyanide could maybe work for that. if you dont want pure cyanide you could always try elderberry juice or bitter almonds, both contain cyanide in small amounts
i see vasodilators would be very unfortunate for you- migraines are vasodilation based iirc
@WeebRemover 4500 No cyanide, thank you...
I use triptane and novaminsulfon.
@Experimental Chemistry or ignite the EtNO2
@Costi Sorry, generally too dangerous for me as a migraine patient...
Nice Video! Did you ever try to reduce the nitrate with potassium sulfite? Are sulfites stronger reducing agents than formates?
No, they aren't.
But the main advantage of the formate method lies in the unsolubility of the oxidized reducing agent: calcium carbonate can easily be filtered off and completely devided from the nitrite in this way. From potassium sulfite the sufate would be formed which is watersoluble like the nitrite. There are already enough impurites in the product, nobody will need one more... 😉
And if anybody would't mind to have potasssium sulfate in the product, why should he use the sulfite? Sulfur would be the stronger reducing agent: putting the stoechiometric amount in small (!) portions in molten nitrate until the last one burned up would be the easier and more effective way (if it is permitted by law in your country).
@Experimental Chemistry Thank you for the detailed answer. My idea was to directly melt the potassium sulfite with the calcium nitrate. The produced sulfate would bind to the calcium from the nitrate, falling out as calcium sulfate, which is insoluable, leaving the potassium nitrite behind. But I guess you are correct, that this process introduces more impurities.
@Haxmoasta This won't function, because the meltingpoint of the educt mixture lies above the decomposition temperature of KNO2...
Using lead, formate, sulfur or carbon are the only successful methods - or spaghetti like Chemplayer did... - in contrast to S and C should this be legal, too, because spaghetti is no component of blackpowder... 😉
@Experimental Chemistry with S and C you get a lot of impurities . I have tried .
@Akhil the Chemist I know - therefore I recommend formate in this video.. 😉
Reaction of nitrite with Fe(2+) ions affords the brown [FeNO(H2O)5](2+) complex. It's a rare example of Fe +1 complex (the other positive charge is in the NO(+).)
That's correct. 👍 But I only have space for 5 test tubes in that transparent stand, so I had to make a choice which typical reactions I should show.
Id be intreseted about the purity of the product. Titration with acidified permanganate works well, but keep the solutions hot, otherwise the reaction is too slow. Certainly seems a lot more feasable than Pb, C, S or spaghetti noodle reduction.
I've tried the reverse manganometric determination before, but it didn't work well, despite heating.
In a spot titration with amidosulfonic acid on iodide-starch paper, I came to a purity of about 80% - but without recrystallizing beforehand, as in the video. After recrystallization, the purity should be significantly higher.
On the other hand, the yield is then so low that it would almost be used up again in the determination.
direct titration with ceric sulphate is supposed to work pretty well, giving a nice clean reaction without the side-reactions you get with permanganate
@lefthandedspanner Sounds interesting.
Do you have detailed test instructions for this?
Which indicator? ferroin? - Unfortunately I don't have it (yet) (very expensive and hard to find).
As I said: the spot titration with amidosulfonic acid on iodine-starch paper showed a purity of about 80% for the impure product - the recrystallized product should therefore probably be at least 95% pure. More than adequate for our purposes.
@Experimental Chemistry the method uses an excess of acidic 0.1 M ceric sulphate, back-titrated with ferrous sulphate, with ferroin as an indicator
APC Pure in the UK sells ceric sulphate at £26 for 25 g, and they ship internationally; the bulk cost is not cheap, but a little goes a long way
@lefthandedspanner Cerium IV sulfate is not a problem. I made it myself from cerium dioxide and NaHSO4 and adjusted the titer with potassium iodide/thiosulphate - but there is also a very cheap one from a supplier in Poland (6 euros for 10 g).
From the UK there would be an additional 19% import sales tax plus 6 euros DHL customs service flat rate - not worth it.
Anyway, I don't order any chemicals from outside the EU: even I only buy legal substances, of course, but I still don't want to be questioned by curious customs...
I only found ferroin as a ready-to-use indicator solution from a Latvian supplier: 50 ml for 16 euros. I have a few other things on my wish list there as well. A few Patreons and maybe I can place an order there... ;-)
Absolutly amazing video! :D
Thank you! 🙂
How about simply decomposing KNO3 (eventually using a vacuum pump to remove the oxygen so Le Chatelier principle would work favorably to nitrite and also to prevent reoxidation to nitatre)?
But how should I know when it's completely done, ending not too early - or not too late, when it further decomposes to K2O?
And how should we get rid off these contamination products as easily as filtering off CaCO3?
The reduction is fast and you can see when it's done: when it smokes no longer... ;-)
And no vacuum pump needed.
Why difficult when it can be done easily?
Furthermore 75 % formic acid is legally, easily and cheaply to obtain...
What are your thoughts on importance of K/Na Nitrite as Precursors ?
Precursors for what?
@Experimental Chemistry Alkyl Nitrites ?
@SERIES EXPERIMENTS Here where I live it is legal to make and posess alkylnitrites, but not to use or sell them as a dru g.
I would't synthesize them anyway - I am suffering from migraine and don't want to get a bad headache... But that's no tragedy, because I would't have any use for alkylnitrites.
Alkali nitrites are not to be bought here, because it's forbidden for german suppliers to sell them online and to send them by shipping because they are poisonous. But it's legal to buy them from our neighbour countries, synthesizing it on your own and posess it.
I use nitrites for other syntheses, i. e. azo dye. I think I will make a video about it in summer.
@Experimental Chemistry ohh ! Soon I will be attempting to synthesize Sudan I dye ! A very basic and easy organic synthesis for my audience.
@SERIES EXPERIMENTS O.k., good luck!👍
I'll prepare Magneson I (Azoviolet), which is a non-carcinogenic azo-dye and a useful indicator.
This was SOOOO much easier to achieve with kno3, from stump remover, and sulfur, not even weighed, but more sulfur than kno3 (sulfur for getting rid of leaf mites). Lit on fire, then after collecting the white dried liquid. Looked like dry toothpaste
If the impurities, especially the formed sulphate, don't disturb in the further use, why not... 😉
FYI: your method is forbidden in my country as a s. c. "pyrotechnical setup"...
And stump removers from the EU don't contain any KNO3...
@Experimental Chemistry OMG!! NO WAY!! i suppose the usa is free after all, compared to some anyways, i do appreciate new and good chemistry methods. In my experience, the sulphates arent so acquired when doing the pyromethod. It is sulfurous, the smoke, ljkely SO2, But not much yellow remains. The nitrite is also a decent gu powder oxidizer, albeit less active. Seems to be a better organic oxidizer than pyrotype. Thanks for responding.
Btw, sensodyne toothpaste contains 5%kno3, but man oh man how expensive!
@All Love Burning S or C in molten nitrate will always carry sulphate resp. carbonate into the product...
I don't use sensodyne, but I think the ingredients will be different here, too, and it's nearly impossible to extract a nitrate from this mixture... It's also not necessary, because it's legal to possess it here - only purchasing it could be a problem: after ordering it online in our country, the police often comes to your door for watching after what are you doing with it... So it's better to order it straight from our neighbours in the EU...
@All Love pyrolysis methods typically have very low yields for nitrite, we have been getting about 20% yields with nitrate/flour reactions
Cool nice hats off for u for preparing fair amounts of nitrite.
You have got the choice: good amounts with many impurities or a relatively pure substance in a small yield - it is nearly impossible to have both with a salt that's so highly soluble...
Perhaps the yield could be enlarged a little bit by sucking off all the adhering nitrite solution from the cristallized impurities by vacuum filtration instead of decanting. On the other hand it might not be the best idea to suck much air through, because the nitrite can easily be reoxidized to nitrate, which would be a contraproductive step then...
@Experimental Chemistry for synthesis purpose ( for preparaing azo dyes etc) a small impurity of nitrate would not affect our synthesis.
@Akhil the Chemist The azo dye was just an example for what I use nitrites (instead of making alkyl nitrites from it for which I have no use and only cause me headaches...). I think in fact I will use my bought sodium nitrite for making magneson, because I will need a little more nitrite than I made now of the potassium salt.
But my video might help some viewers who have no access to nitrites. I know only two suppliers in the EU who sell nitrites to private persons, and only one of them offers also potassium nitrite - but the chems that once run out off his stock will never be replaced again there...
@Experimental Chemistry what was the final percentage yield ?
@Akhil the Chemist Only 20 % - compared to the theoretically possible yield... 😞
... but it's near to 99 % pure then - I tested it with a titration in an earlier run... Without crystallizing out the impurites you'll just get about 60-80 % pure stuff, much potassium carbonate and some leftover nitrate in there...Such a mixture is unusable for analytics - only for qualitative usage/quick'n'dirty syntheses where alkaline carbonate don't matter... Perhaps for making alkyl nitrites by using double amounts and letting CO2 just bubble out on adding even more HCl, too... 😉
But for example making nitrosyl sulfonate with the impure stuff gave me a failure, while repeated with pure nitrite succeeded. Perhaps I' ll make a video about this nice synthesis, too...
nitrite into HCL gives largely nitrosyl chloride
That's true, with hydrogen chloride gas and, as an intermediate, also with concentrated hydrochloric acid, but not with semi-concentrated hydrochloric acid, which was used in the video.
The more water is involved, the faster nitrosyl chloride decomposes back into hydrogen chloride and nitrogen oxides.
When I called hydrochloric acid a strong acid, I was referring to the actual strength of the acid, not the concentration. I have to admit that this could of course have been more precisely formulated.
couldn't you skip the first step and add Na/K nitrate solution to Ca formate solution made from Ca Carbonate (chalk) and your formic acid?
Yes, of course you could, but
1. Calcium nitrate is a little easier to get hold of than potassium nitrate where I live.
2. Either way, there are two work steps, regardless of whether you first produce calcium formate and then mix it with potassium nitrate, or whether you mix calcium nitrate with potassium carbonate and then win the formate with formic acid.
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The copper complex is formed with 6 nitrites? I believed there were 4. What is your source? because I didn't find it on the internet, not even in English...
I found that on MEL chemistry (YT).
There are just 4 ligands in cations like tetrammincopper, but 6 when nitrite forms an complex anion with divalent Cu.
would this work for the sodium salt?
Probably you may have more loss because the decomposition temperatur of the sodium salt is nearer by the reaction temperatur between nitate and formate than in case of the potassium salt.
Could you use sodium formate and potassium nitrate
Potassium nitrate of course, but only calcium formate works this way, because you have to get rid off the carbonate afterwards, which was previously formed from the formate - and only calcium carbonate is unsoluble in water and can therefore be filtered off easily.
@Experimental Chemistry ya, that makes sense. The higher the temperature of the water then less soluble the calcium will be. I forgot about that
@dAn archy Ahm, no... CaCO3 is nearly unsoluble in water - no matter if it's hot or cold. It only dissolves to CaHCO3 on access of CO2 (watch our video about water hardness), which isn't the case here. I guess you confused a few things... ;-)
The formation to CaCO3 is necessary here to get rid off the carbonate by filtration, otherwise it contaminates the endproduct...
That's the reason why sodium formate shouldn't be used.
@Experimental Chemistry oh ok. I'm still learning. All I watch is chemistry videos
@dAn archy No problem. That's what we are here for. Please always ask, if you have a question. 🙂
Experimental Chemistry - 2022-12-21
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