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Wolfram
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Very nice
Very nice but I assume that you better have a god ventilation doesn´t there come a huge cloud of smoke that fills your kitchen from the reaktion?
[Edited on 5-12-2003 by Wolfram]
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Wolfram
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I found this..
1 Cr2O3 + 2 Na2CO3 + 3 NaNO3 = =>
2 Na2CrO4 + 3 NaNO2 + 2 CO2
[Edited on 5-12-2003 by Wolfram]
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TrollchEmist
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Yes you're right about huge smoke and it's better to do this reaction outside or have a very good ventilation. CO is toxic gas (takes
oxygens place in hemoglobin) so be careful.
-TrollchEmist-
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Microtek
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The problem with this violent reaction is that, while some nitrite probably has been produced, a lot of the NaNO3 has probably reacted something like
this:
4NaNO3 + 5C --> 5CO2 + 2Na2O + 2N2
and then Na2O + CO2 --> Na2CO3
which is alkaline and gives bubbles when acid is added.
One way to check for carbonate is to add a little CaCl2 or Ca(NO3)2 in water to some of your product in water solution. If carbonate is present, you
will see a precipitate ( CaCO3 ) after some stirring.
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TrollchEmist
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I agree with you. Did one synthese with 'propable' NaNO2 and yield was very low.
but there were NaNO2 present(tiny amounts) reaction is too violent with only charcoal.
sorry 
Have to try different methods.
-TrollchEmist-
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guaguanco
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If you have a source of NO2...
http://palimpsest.stanford.edu/don/dt/dt3203.html
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TrollchEmist
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Yeh. This is what I'll try:
One need Pure nitric acid and Cu powder and NaOH or Na2CO3 Reaction is this:
Cu + 4HNO3 --> Cu(NO3)2 +2NO2 + 2H2O
if used concentrated nitric acid. reaction would be:
3Cu + 8HNO3 --> 3Cu(NO3)2 + 2NO + 4H2O
So drop HNO3 on Cu powder and bubble formed NO2 gas trough NaOH or Na2CO3 water solution. I assume that NaNO2 would form.
This looks promising, I'll try it soon and report.( maybe after christmas)
[Edited on 13-12-2003 by TrollchEmist]
-TrollchEmist-
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unionised
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Would someone care to balance the equation
NO2 + Na2CO3 --> CO2 + Na NO2
And do be careful disolving the gas, if it sucks carbonate solution back into the acid you will have problems.
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guaguanco
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| Quote: | Originally posted by unionised
Would someone care to balance the equation
NO2 + Na2CO3 --> CO2 + Na NO2
And do be careful disolving the gas, if it sucks carbonate solution back into the acid you will have problems. |
Good point, it's probably NO that is the required oxide.
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unionised
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Would someone care to balance the equation for NO please?
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Microtek
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Na2CO3 + NO + NO2 --> 2NaNO2 + CO2
I have tried this using 50% HNO3 and starch to produce the N2O3 gas ( the equimolar mix of NO and NO2 acts as if it is N2O3 ). As HNO3 is consumed and
the concentration drops, a greater proportion of NO is produced. If only NO2 is used, there will be produced some nitrate ( but using K2CO3 should
make that easy to remove )
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pyroscikim
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Try sulphur as reducing agent for nitrate salt, as i doubt it reduces nitrites.
just add it slowly to molten nitrate to form nitrite and sulphur dioxide which vents off. the excess sulphur will melt and form a lump which is easily
removed upon cooling. It also ensures that all nitrate reacts.
and isn't this a discussion to make *pure* nitrite?
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KABOOOM(pyrojustforfun)
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Inert gas is needed as autoignition T for S is 232°C
some polynitroaromates hydrolyze in alkali conditions forming nitite salt and the nitrogroup replaces with a -OH or with a -NH<sub>2</sub>
if ammonia is used (plus ammonium nitrite)
of course it is not worthy as a way to produce nitrites but as a byproduct of preparation of some explosives
eg preparation of TATB from pentanitroaniline and ammonia should produce 2 mol ammonium nitrite per PNA. and preparation of styphnic acid from
tetranitroaniline produces 1 mol nitrite per mol of TNA
H<sub>2</sub>NC<sub>6</sub>(NO<sub>2</sub> <sub>5</sub> + 4NH<sub>3</sub> <s> ></s> TATB +
2NH<sub>4</sub>NO<sub>2</sub>
H<sub>2</sub>NC<sub>6</sub>(NO<sub>2</sub><sub>4</sub>H + 3NaOH <s> ></s>
Na<sub>2</sub>(O-)<sub>2</sub>C<sub>6</sub>(NO<sub>2</sub><sub>3</sub>H + NaNO<sub>2</sub> + NH<sub>3</sub> + H<sub>2</sub>O
the nitrogroup which is replaced is the one which doesn't agree with other groups about the position it activates (it's the way I construed
for myself)
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Ramiel
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pyroscikim, I tried your method. It is pretty labor and time intensive.
I don't know if I'm doing it improperly, but as I add the Sulphur, The molten Pot. Nitrate solidifies and cakes up in weird ways -
preventing any furthur reaction.
In addition, I mixed an excess of sulphur to pot nitrate and then ignited it (by reaching it's flashpoint and, in a seperate reaction, by adding
burning coke) with similar complications.
From experimental experience, the low yeilds of NaNO<sub>2</sub> from the carbon-type reaction are fairly acceptable once you take into
account the ease of the reaction.
perhaps some investigation into a wet reaction would pay dividends?
p.s. woof, I'm still a bit light headed from all that SO<sub>2</sub>! it's a bit like being drunk so I apologise if the post is
hard to follow in places. 
In fact, my brain insisted that I take a lie down mid-experiment. Is this bad? 
Caveat Orator
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unionised
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Sulphur reduces sodium nitrite on heating.
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Nick F
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What about :
Getting hold of some CaO - either buy it, or make it from limestone or whatever. There are many options for getting this.
Get some sulphur, and place in a two-holed container. The sulphur is ignited, and dry air is pumped into one hole. The gas coming out of the other
hole is passed over your CaO, forming CaSO3.
This is mixed with your nitrate, and the mixture is fused. After the reaction is over, cool the mixture, dissolve in water, filter off CaSO4,
crystalise, recrystalise, dry. You should have quite pure XNO2.
It's a slight modification of one proccess that passes SO2 over a fused mixture of CaO and XNO3. I just think it'd be easier if you
didn't have to handle high temperatures and toxic gases at the same time.
Actually, you might be better off making the SO2 from sodium metabisulphite (wine/brewing suppliers...) and a strong acid, preferably H2SO4 (conc.)
since this would produce dry SO2. Then you don't need to pump any air. Or you could get it by reducing H2SO4 with zinc. Again, there are many
possibilities. I think I'd prefer the sodium metabisulphite route actually.
SO2 absorption by dry solid CaO might be quite slow, in which case you could bubble the SO2 through a suspension of Ca(OH)2 in water, and dry the
CaSO3 afterwards.
I think I'd use a method like that if I needed to make some.
Edit: if you were feeling adventurous and had a good freezing mixture to hand, you could pass your SO2 into a container of CaO that had been chilled
to about -20*C. The SO2 would condense and soak into your CaO, which might give you a better reaction.
[Edited on 7-1-2004 by Nick F]
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Polverone
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another rejected method
I buy NaNO2, but it's something that I'd like to be able to make should I ever need to. I wondered if tin metal (somewhat expensive, I know)
might be able to reduce NaNO3 to NaNO2. I used lead-free solder that was mostly tin, along with a little silver and other undisclosed components.
Conclusion: it is an effective reducing agent, but sometimes too effective. I overheated the test tube that had my molten NaNO3 and solder in it, and
there was a flashing/glowing ignition in the tube that spewed smoky NO2 out of the tube and melted a hole in the bottom. On another attempt I heated
the two together without an ignition, and the strong evolution of NO2 on acidification showed that nitrite was definitely present. But this method
seems about as tricky as using molten lead to effect the reduction, and tin's more expensive (and easier to start fires with).
I found a very brief reference in some reaction reference manual that heating a neutral solution of KNO3 with zinc dust would reduce it to KNO2. No
details were offered, and my couple of attempts were unsuccessful. However, when I boiled NH4NO3 solution with lead dust some time ago, I did form
some lead nitrite. I could tell from the coloration of the solution and the evolution of NO2 on slight acidification.
Edit: reading a post by Organikum elsewhere makes me wonder if my zinc dust is too pure to effect the reduction of MNO3 to MNO2 in neutral aqueous
solution. The original reference was from the 1880s.
[Edited on 1-7-2004 by Polverone]
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jimwig
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Just for the record.
Melted lead (unknown purity) over wood fire in large kitchen spoon. Added some agricultural grade NaNO3 to molten lead.
Presently a reaction happened- bubbles etc. The spoon contained a water soluble yellowish powder/crystals along with other gunk.
Pb + NaNO3 = NaNO2 + PbO (?)
I have not tried this again but will soon.
I want this to work with charcoal but just agricultural grade charcoal. Activiated is available but precious for other non-substitute type reactions.
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jimwig
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the history of nitrite production is summarized in <A
HREF="http://l2.espacenet.com/espacenet/bnsviewer?CY=gb&LG=en&DB=EPD&PN=US4312722&ID=US+++4312722A1+I+">US4312722</A&g
t; (patent)
[Edited on 2-10-2004 by Polverone]
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