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Author: Subject: [Alkali Earth Metal] Nitrite
Nidias91
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[*] posted on 18-1-2006 at 18:01
[Alkali Earth Metal] Nitrite


I have found many syntheses for various alcoholic nitrites, and they all have the basic formula of:

Nitrous Acid + Alcohol

Well, I know that Nitrous Acid is made with H2SO4 and a nitrite salt. The one that all of the syntheses I have read is NaNO2. I was just wondering, how would I produce NaNO2 or KNO2 from their respective nitrates?

By the way, this is my first post at ScienceMadness. Make suggestions if you want I guess. All help is appreciated.
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The_Davster
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[*] posted on 18-1-2006 at 18:08


The procedure is the exact same, just do some calculations to ensure the mass of KNO2 used contains the same number of moles of NO2- ions as the mass of NaNO2 called for in the procedure.


EDIT: OOps...I misread what you were asking, but we have a thread dedicated to making nitrites from nitrates and Pb, Magpie has semi-recently posted a very nice description of it with pictures.

[Edited on 19-1-2006 by rogue chemist]




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Nidias91
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[*] posted on 18-1-2006 at 18:29


Sorry if I was vague before, I figured that I would be. I was asking how I would produce NaNO2 or KNO2 from NaNO3 and KNO3 respectively.

I remember something about producing KNO2 from KNO3 by heating KNO3 at several hundred degrees for a few hours.. I'm not really sure though.
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Lambda
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[*] posted on 18-1-2006 at 18:57
Heating KNO3 to several hundred Degrees Celcius (?)


Dear Nidias91, heating KNO3 to a melt of several hundred Degrees Celcius is a big NO !! NO !!. The melt is known to even Detonate !! (Bretherick ???).

In the laboratory, Lead (Pb) is used to reduce the KNO3 or NaNO3 to the corresponding Nitrites. I have the procedure in Dutch, and I wil have to translate it for you from "Chemische Preparaten" by Drs. L. P. Edel (Kluwer).

Please have patients, and give me two days to find the book and do the translation.
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[*] posted on 18-1-2006 at 19:18


Please consult the following thread for more details, and continue the discussion there.

https://sciencemadness.org/talk/viewthread.php?tid=52


Please search in the future to avoid double posts.

[Edited on 19-1-2006 by chemoleo]




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Nidias91
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[*] posted on 18-1-2006 at 19:28


Lambda thank you VERY much. I'm not sure if my email is in my profile so : nidias91 at gmail.com

and chemoleo, i will gladly do that, thank you
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[*] posted on 18-1-2006 at 20:02


There is little danger in heating KNO3 as hot as you please, so long as it is pure. However, it is not a very good method for nitrite production: the equilibrium does not tend very far toward nitrite with simple heating in air.



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Lambda
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[*] posted on 18-1-2006 at 21:08


IIRC "Bretherick" makes mention of KNO3 detonating at ~1100 Degrees Celsius.

Melting KNO3 should not present any kind of problem, just like Polverone has mentioned. But want's the melt has cooled down, only to find out that hardly, if any KNO2 has been formed. Trying to then superheat the melt inorder to push the equation in favor of KNO2, may lead to an explosion, as mentioned in the above hazardous situation.

KNO3, is used in some old "Gun Blueing" recipes in it's melted form, at controlled temperatures.

Reducing KNO3 to KNO2 via a procedure with molten Lead, not only can take place at a much lower heating temperature, but has the advantage of an easily controlled, high yield manner of cheap OTC chemicals synthesis.

KNO2 is relatively expensive to buy, and can be made so cheap !:)
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[*] posted on 19-1-2006 at 02:51


That is much much too hot. I have mentioned temperature ranges before, and the reason why some have had no success. Even at that temperature range, O2 evolution continues for quite some time, though you need to look very carefully to see it at the surface. Loss of nitrogen is very small at these temps, and I doubt that there is any danger from explosions or NO2.

[Edited on 19-1-2006 by S.C. Wack]
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Lambda
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[*] posted on 24-1-2006 at 17:56
Potassium Nitrite - KNO2


Here you are Nidias91, the synthesis of Potassium Nitrite.

Kaliumnitriet - KNO2 (Nederlands = Dutch)

In een ijzeren kroes smelt men 100 gram kaliumnitraat (KNO3) en voegt dan onder roeren met een ijzeren spatel in kleine porties 204 gram lood (Pb) bij de smelt. De oxydatie van het lood verloopt zeer levendig en in een half uur (30 minuten) kan de reactie ten einde zijn. Men giet de nu dikvloeibare massa op een groot blik uit om de massa gemakkelijker klein te kunnen maken. Het reactieprodukt wordt in een mortier zo fijn mogelijk gestoten en enige keren met weinig kokend water uitgetrokken. De verkregen oplossingen worden onmiddellijk heet door een vouwfilter gefiltreerd. In het nog hete filtraat leidt men gedurende korte tijd koolzuur (CO2) om het lood dat in oplossing gegaan is als carbonaat neer te slaan. De oplossing wordt weer gefiltreerd en op een waterbad ingedampt. De oplossing wordt eerst met iets salpeterzuur (HNO3) geneutraliseerd en men laat afkoelen. Het uitgekristalliseerde kaliumnitraat (KNO3) wordt afgezogen, de vrij zuivere oplossing van kaliumnitriet (KNO2) wordt tot droog ingedampt en het verkregen zout wordt op de vrije vlam to smelten gebracht. Het nu watervrije zout wordt weer op een blik uitgegoten, klein gemaakt en nog warm in een goed sluitbare fles gedaan.

Bron:

Chemische Preparaten
Derde Druk
Drs. L. P. Edel
Kluwer - 1965
Deventer - Antwerpen

Bladzijde: 64




Potassium Nitrite - KNO2 (Translated text from Dutch to English)

In an Iron crucible, melt 100 grams of Potassium Nitrate (KNO3), and add wile stirring with an Iron spoon, in small portions 204 grams of Lead (Pb) into the smelt. The oxidation of the Lead goes very lively, and in about a half an hour (30 minutes) the reaction may have finished. Pour the now pasty mass, onto a large Iron sheet metal plate, in order to be able to easily crush it up into small pieces. In a mortar, these small pieces are ground down as fine as possible, and extracted a few times by means of a small amount of boiling Water (H2O). The resulting extract, is immediately filtered through a folded filter while it is still hot. Through the still hot filtrate, and during a short period of time, Carbon Dioxide gas (CO2) is bubbled so that the Lead that was still present in solution may now precipitate as the Carbonate. The solution is again filtered and evaporated by means of a hot Water bath (100 Degrees Celsius). The now resulting solution is neutralized by means of a small amount of Nitric Acid (HNO3) and left to cool down. Crystallized Potassium Nitrate (KNO3) is removed from the solution by means of suction filtration, and the now rather pure solution of Potassium Nitrite (KNO2) is evaporated to dryness, and melted by means of the open flame. The now Water-Free salt is again poured onto an Iron sheet metal plate, crushed up into small pieces, and while it is still warm, put into a well sealed bottle.

Source:

Chemische Preparaten
Third Edition
Drs. L. P. Edel
Kluwer - 1965
Deventer - Antwerp

Page: 64
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[*] posted on 24-1-2006 at 23:52


You use iron tools for mixing and also as surface, where the melt is allowed to cool down. Don't you expect contamination with the iron? I can imagine that the molten nitrate also reacts with iron and that you get iron (III) contamination in the melt, which may be hard to remove.



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neutrino
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[*] posted on 25-1-2006 at 04:06


Assuming the iron surface is clean of oxide and the melt from the reaction solidifies as soon as it touches the cold metal, there shouldn't be any significant contamination. The Fe contamination from the iron tools used in the reaction should precipitate with the lead as the carbonate.
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