Sciencemadness Discussion Board

Nitric Acid

liquidlightning - 26-7-2012 at 18:10

Having some problems making nitric acid. My setup is this:
Vacuum flask with HCl and NaNO2, all heated to about 55C. The side arm leads to a flask of water in an ice bath, which has a hose leading to a flask of bicarb for nitric oxide/excess nitrogen dioxide.

Even after about 1 hour of bubbling nitrogen dioxide through the water, the acid produced is still very dilute. Am I doing something wrong?

EDIT: Forgot to say, I have an air pump bubbling through the vacuum flask through a glass tube in the stopper. The air oxidizes the nitric oxide to nitrogen dioxide.

[Edited on 27-7-2012 by liquidlightning]

ScienceHideout - 26-7-2012 at 18:44

If I am not mistaken, your reaction probably produces nitrous acid.

Use a nitrate rather than a nitrite to get a good yield :-)

bbartlog - 26-7-2012 at 19:09

I don't understand your setup. Isn't HCl more volatile than nitric acid? Won't you just get mixed HCl/water coming over first? I mean, maybe some NO is produced as well but it does not look like a promising setup to me. Where did you get the idea?

Nitric acid

cal - 26-7-2012 at 19:33

Use 700 grams sodium nitrate to 500 ml distilled water, heat till boils. Cool and add 280 ml concentrated sulfuric acid 20 ml at a time every 15 minutes until all acid is added. Let cool as this is a exothermic reaction, then filter salt and decant. Place in a freezer over night. Filter remaining salt and then distill the nitric acid for concentrated Nitric acid. I use this method to make all my Nitric Acid as it is the easiest way with very little fumes.:cool:

liquidlightning - 26-7-2012 at 20:16

I don't distill the mixture. It produces nitrous acid, which is very thermally unstable and decomposes to nitrogen dioxide and nitric oxide.

jamit - 26-7-2012 at 23:32

Quote: Originally posted by cal  
Use 700 grams sodium nitrate to 500 ml distilled water, heat till boils. Cool and add 280 ml concentrated sulfuric acid 20 ml at a time every 15 minutes until all acid is added. Let cool as this is a exothermic reaction, then filter salt and decant. Place in a freezer over night. Filter remaining salt and then distill the nitric acid for concentrated Nitric acid. I use this method to make all my Nitric Acid as it is the easiest way with very little fumes.:cool:


@Cal

What concentration of nitric acid do you get from your method? Azeotropic 68%??

liquidlightning - 27-7-2012 at 01:32

That reaction should yield fuming nitric, if some excess sulfuric is used to prevent water from azeotroping.

jamit - 27-7-2012 at 04:26

Quote: Originally posted by liquidlightning  
That reaction should yield fuming nitric, if some excess sulfuric is used to prevent water from azeotroping.


Are you sure? Or is that your guess? Have you done this experiment?
How do you explain the 500 ml of water?

liquidlightning - 27-7-2012 at 11:00

Ah, I seem to have missed the water. Why is the water added? Doesn't this reaction work perfectly fine using just conc. sulfuric and nitrate?

Farmerjohn - 4-9-2012 at 18:45

What do yall think of these methods?

http://www.youtube.com/watch?v=2yE7v4wkuZU

ItalianChemist - 5-9-2012 at 07:39

Quote: Originally posted by Farmerjohn  
What do yall think of these methods?

http://www.youtube.com/watch?v=2yE7v4wkuZU

Using the first two methods you can only obtain weak and not concentrate acid, using the last one you will obtain a great final product!
The reaction works using NaNO3 and not NaNO2, with NaNO2 you will obtain nitrous acid!
And instead of HCl use concentrate H2SO4, which is less volatile than HNO3!

SM2 - 5-9-2012 at 08:40

If I'm not mistaken, as long as you saturate your nitric with excess N02/N204, it will be fuming. Cal's method has a certain elegance, and some real advantages.

cyanureeves - 5-9-2012 at 14:39

i have done cal's method. it was made a video on you tube by metalic mario and it does produce nitric although heavily mixed with sulfuric acid of course. the nitric does dissolve sterling fairly easy and especially if you heat the nitric mixture and i always thought this would be better for making gun cotton. i think liquidlightning is missing a piece of copper and aluminum to speed the reaction but will only capture red nitric fumes mostly but it will still make nitric acid although weak.

[Edited on 5-9-2012 by cyanureeves]

vmelkon - 6-9-2012 at 07:55

Quote: Originally posted by cyanureeves  
i have done cal's method. it was made a video on you tube by metalic mario and it does produce nitric although heavily mixed with sulfuric acid of course.


It wouldn't be heavily polluted with H2SO4 because H2SO4 doesn't evaporate much. I have distilled battery acid and the water that comes off, I collected it and then poured on NaHCO3 and there was no fizzing at all. It should be the same for the H2SO4 + HNO3 + Na2SO4 mixture.

AJKOER - 6-9-2012 at 13:01

Excuse me if I feel that creating dilute Nitric acid from a nitrate salt is not very creative.

Instead, prepare it from heating aqueous ammonia and an excess of K2FeO4, for example, which could directly produce a nitrate:

8 K2FeO4 + 3 NH3 + (n+2)H2O --> 3 KNO3 + 4 Fe2O3.nH2O + 13 KOH

The optimal pH is reported between 7.5 to 11 with a temperature between 10C to 35C for nitrate production (see page 10, Equation 3 at https://kb.osu.edu/dspace/bitstream/handle/1811/36335/OH_WRC... ).

Another, more interesting route is the action of H2O2 on ammonia in the presence of a catalyst (any of NaOH, Na2CO3, Zn dust, Pt or Pd-H2). To quote Formatik (see http://www.sciencemadness.org/talk/viewthread.php?tid=6650 ):

"H2O2 forms (even in very dilute solutions) nitrite very rapidly, if the H2O2 solution is mixed with a few drops of NH4OH and a little NaOH or Na2CO3, and this then boiled in a retort to a very small volume. They suggest this nitrite formation as a demonstration experiment because it is very quick to do, and then after acidification of the colorless liquid with H2SO4, the HNO2 can be nicely be proven to be present."

With the nitrite, per Wiki ( http://en.wikipedia.org/wiki/HNO2 ): "When cold, dilute solutions of nitrite ion, NO2− are carefully acidified, a light blue solution of nitrous acid is produced. Free nitrous acid is unstable and decomposes rapidly.
In anything other than very dilute, cold solutions, nitrous acid rapidly decomposes into nitrogen dioxide, nitric oxide, and water:
2 HNO2 → NO2 + NO + H2O
Nitrogen dioxide disproportionates into nitric acid and nitrous acid in aqueous solution:[2]
2 NO2 + H2O → HNO3 + HNO2
In warm or concentrated solutions, the overall reaction amounts to production of nitric acid, water, and nitric oxide:
3 HNO2 → HNO3 + 2 NO + H2O"

Poppy - 6-9-2012 at 13:11

Stop making nitric acid. Some activists purposedly enganged to stop fertilezer companies from making nitric acid as it will inevitably deplete the nitrogen reservoir of the earth in a matter of years.

AJKOER - 6-9-2012 at 14:45

Quote: Originally posted by Poppy  
Stop making nitric acid. Some activists purposedly enganged to stop fertilezer companies from making nitric acid as it will inevitably deplete the nitrogen reservoir of the earth in a matter of years.


The use of synthetic methods for the production of nitrates were developed at the end of World War I. Basically, oxidation of NH3 from N2 and H2 in the presence of a catalyst.

Nitrogen reservoir? Air is the source of the N2 and if one explodes one nitrates, it is recycled, so who said being green was dull? So, if you overdue your nitrates and accidentally blowup the neighborhood, you could always sue Green 'Peace' for improper labeling, or promoting improper recycling.

[Edited on 6-9-2012 by AJKOER]

Lambda-Eyde - 6-9-2012 at 14:50

Quote: Originally posted by Poppy  
Stop making nitric acid. Some activists purposedly enganged to stop fertilezer companies from making nitric acid as it will inevitably deplete the nitrogen reservoir of the earth in a matter of years.

You aren't serious now, right? Or are you thinking of phosphorus?
Quote: Originally posted by AJKOER  
The use of synthetic methods for the production of nitrates were developed at the end of World War I. Basically, oxidation of NH3 from N2 and H2 in the presence of a catalyst.

A little correction here; the Birkeland–Eyde process was actually developed before WWI.

[Edited on 6-9-2012 by Lambda-Eyde]

AJKOER - 6-9-2012 at 15:10

Quote: Originally posted by Lambda-Eyde  
Eyde_process]Birkeland–Eyde process[/url] was actually developed before WWI.



Per Wiki ( http://en.wikipedia.org/wiki/Birkeland%E2%80%93Eyde_process ): "Therefore, in the 1910s and 1920s, it was gradually replaced in Norway by a combination of the Haber process and the Ostwald process....The ammonia from the Haber process is then converted into nitric acid (HNO3) in the Ostwald process."

Actually, my memory recalled so old work noting that a single country was the source of saltpeter and the implications of a supply interruption.

cyanureeves - 6-9-2012 at 15:17

uh sorry about all that stuff i wrote. i have never done anything with nitrite only nitrate. amazing how just one less oxygen atom can make a man write all kinds of false crap.