Sciencemadness Discussion Board

Nitrite to nitrate!!

SAM4CH - 4-8-2006 at 13:15

Is it possible to oxidize nitrite to nitrate by chemical reaction? it is possible in biochemical reaction using Nitrobacter!!
What about electrolysis aqueous solution of nitrite using platinum or PbO2 anode!?

guy - 4-8-2006 at 13:17

How about H2O2 or even oxygen?

kclo4 - 4-8-2006 at 13:41

why would you want to turn nitrite into nitrate?

i think nitrite is much more usefull and harder to get,

but electrolysis will work, so would adding an acid like HCl or possibly HNO3 , the reason is HNO2 would form, decompose into HNO3 and NO? then the HNO3 would react with the KCl formed, making KNO3 and HCl again, but you would still get KCl in there so then you would have to crystalize one of the 2 out to get it pure :)

Solomon - 26-6-2013 at 17:13

Potassium nitrate becomes potassium nitrite when heated if that is at all relevant.

Bot0nist - 26-6-2013 at 17:35

See the first line of my signature...

Making nitrite from nitrate is not nearly as simple as heating... There is a long thread on this.

To have your nitrite go to nitrate, just make a solution of it in water, and wait, as it is slowly oxzidised. Maybe bubble air or O2 through to speed it up. Probably can buy KNO3 at a local vendor. KNO2 can be harder to find OTC...

violet sin - 26-6-2013 at 17:42

KClO4- you can buy nitrite for curing salmon roe in some ACE hardware stores ~13$/2#'s IIRC.

Solomon- ya you heat it(nitrate) and oxygen is released, but to put it back in isn't that easy. In the sci mad library is a book( forgot which) that explained the return to nitrate. I don't think you would get a high purity though and I'm fairly certain >400'C was required for that.

I'm away from home and using an ITouch for internet access or I'd search for the book. Bout all I can do on this thing is read and type at a VERY SLOW rate so sorry fro the lack of citation.

woelen - 27-6-2013 at 05:51

Nitrite is easily oxidized to nitrate by common oxidants like KMnO4 and K2Cr2O7. But as others said, making nitrate this way is exceedingly non-economical. Nitrite is harder to get and separating the nitrate from the metal salt solutions is an additional complicating step.

The other way around is quite difficult. Aqueous solutions of nitrate are not at all easily reduced to nitrite. Of course you can make HNO3 from nitrate and reduce that, but in that case you don't get a nice clean reaction. Reaction of HNO3 as oxidizer is not clean at all, it produces a mix of products (NO, NO2, HNO2, or even N2).

[Edited on 27-6-13 by woelen]

Fantasma4500 - 27-6-2013 at 14:08

i was exactly thinking about Cr2O7 in which can be made decently pure and perhaps even 99.9% pure (i dont like working with this stuff, the toxicity is coming close to cyanide, and perhaps even beyond in effectiveness / unluckyness)

ive seen KNO2 and KNO3 sold for same purpose on ebay de, as pökesalz.. im very sure that the KNO2 was cheaper..

1kg KNO2 > 1.6 euro
1 kg KNO3 > 28 euro :O

yes theres not alot of good offers on kno3 up ATM but still..

i suppose putting a hose with holes poked in all over the bottom of it, then leading air through that in a bucked of KNO2 should turn it into KNO3, just dont know how long time you would need to do this, you could perhaps make nitrite tests for it over time

AndersHoveland - 27-6-2013 at 14:08

Nitrite is very easily oxidized. In fact, you can oxidize it to nitrate just by passing air into a solution of it.

This is the reason it is important to store sodium nitrite in air tight containers.

Sodium nitrite forms nice opaque cubic crystals, easy to identify. Sodium nitrate supposedly forms rhombohedral crystals, but I would not be surprised if they appeared more needle-like.
Quote: Originally posted by woelen  
Aqueous solutions of nitrate are not at all easily reduced to nitrite.

True. However, nitric acid, even when dilute, can be reduced with nitric oxide.

And it is still easier to reduce nitrate than it is to reduce aqueous solutions of perchlorate.


[Edited on 27-6-2013 by AndersHoveland]

Pok - 28-6-2013 at 03:03

Quote: Originally posted by Antiswat  
ive seen KNO2 and KNO3 sold for same purpose on ebay de, as pökesalz.. im very sure that the KNO2 was cheaper..

Pökelsalz is ordinary table salt (sodium chloride) with only a tiny amount of sodium nitrite (0.4-0.5%). This is required by law. So nitrites are not that easy to get.

The KNO3 is often sold as pökelsalz in the chemicals section on ebay. The price is so high because of "bomb chemists" who need this stuff and will pay every price. Usually, it's very cheap (for people with a licence, e.g. butchers or farmers (fertilizer)).

I don't think that nitrites are so easily oxidized that O2 from the air will be sufficient to do this job reasonably fast. If you let your nitrite stand for years, yes. But not by bubbling air through a nitrite solution. I think H2O2 is the best solution.

[Edited on 28-6-2013 by Pok]

AndersHoveland - 28-6-2013 at 10:36

Aqueous chlorine also easily oxidizes nitrite to nitrate.

NaNO2 + Cl2 + H2O --> NaNO3 + 2 HCl(aq)


It should be noted, however, that if the acid concentration starts becoming very high (20-30% conc. HCl) an equilibrium will start to be established, and the HCl will partially reduce the nitrate.

AJKOER - 3-7-2013 at 13:25

Quote: Originally posted by AndersHoveland  
Aqueous chlorine also easily oxidizes nitrite to nitrate.

NaNO2 + Cl2 + H2O --> NaNO3 + 2 HCl(aq)


It should be noted, however, that if the acid concentration starts becoming very high (20-30% conc. HCl) an equilibrium will start to be established, and the HCl will partially reduce the nitrate.


Here is a reference on the oxidation of nitrite to nitrate in an aqueous environment ( see Equation [1] at page 1350 link: http://www.mendeley.com/catalog/kinetics-mechanism-nitrite-o... ).

The reaction with Chlorine water would, I presume, proceed as follows:

Cl2 + H2O <--> HCl + HOCl
HOCl + NaNO2 --> NaNO3 + HCl

Of more interest to some (and advanced chemistry) is what happens in highly ionic environments, as per Equation [2] per the above source:

NaNO2 + HOCl --Highly Ionic Environments--> NaOH + ClNO2

where the ClNO2 is noted as an intermediary compound. See also a different source in a biochemical setting (page 12061 at http://www.pnas.org/content/99/19/12061.full.pdf )

Other sources note the important of both ionic strength and surface area (like porous SiO2) in atmospheric chemistry (see http://www.pnas.org/content/early/2009/07/17/0904195106.full... ).

My take on how the chemistry/products of Equation [1] and [2] could interconnect:

2 HOCl + 2 HNO2 --> 2 HNO3 + 2 HCl
2 HNO3 = N2O5 + H2O
[NO2+][NO3-] + HCl --> ClNO2 + HNO3 (see eq [6] per last source)

Net so far:

2 HOCl + 2 HNO2 --> HCl + H2O + ClNO2 + HNO3

Now, per this good source, page 666 http://site.iugaza.edu.ps/bqeshta/files/2010/02/94398_16.pdf on the hydrolysis of nitryl chloride:

H2O + ClNO2 --> HCl + HNO3

So final net reaction:

2 HOCl + 2 HNO2 --> 2 HCl + 2 HNO3

or:

HOCl + HNO2 --> HCl + HNO3

as stated previously. So, removing/limiting H2O under the proper conditions, may create some NO2Cl as an intermediate product.
------------------------------------------------------

[EDIT] On the exposure of nitrite salts to air, per this source (http://copper.atomistry.com/cupric_nitrite.html ) with respect to Cupric nitrite, for example , to quote:

"The nitrite is only known in solution, prepared by addition of lead nitrite to cupric-sulphate solution. Exposure of its dilute solution to air causes slow formation of nitrate. On evaporation of a concentrated solution over sulphuric acid, there is partial decomposition in accordance with the equation

3 Cu(NO2)2 = Cu(NO3)2 + 2 CuO + 4 NO.

It forms a number of complex nitrites with other metals."

However, even absence air in an aqueous solution may cause decomposition in time as for example with Lead nitrite (http://lead.atomistry.com/lead_nitrites.html ), to quote:

"Lead nitrite solution slowly decomposes thus:

3Pb(NO2)2 + 2H2O = Pb(NO3)2 + 2Pb(OH)2 + 4NO,

a decomposition similar to that which nitrous acid itself undergoes;"

Apparently, however, even stable nitrites like for example NaNO2 to quote (http://sodium.atomistry.com/sodium_nitrite.html ):

"In aqueous solution at 100° C. and between 50 and 55 atmospheres of pressure, sodium nitrite is not oxidized by prolonged contact with oxygen, even in presence of a catalyst."

upon acidifying, and at times with an appropriate metal catalyst, are prone to oxidization. For example, in the case of NaNO2 to quote:

"At 60° C. in an atmosphere of carbon dioxide free from air, a 5 per cent, solution of sodium nitrite is decomposed by metallic copper, with evolution of nitrous fumes, but there is not sufficient evidence to enable the course of the reaction to be indicated by means of an equation. "

Interestingly, the latter comment implies that with NaNO2, CO2, Cu and O2, one could make HNO3.


[Edited on 4-7-2013 by AJKOER]

testimento - 3-7-2013 at 22:13

Could exposing the nitrite to ozone help? One could make ammonium nitrate from ammonia with it, so it should be pretty convenient. Or then just sell the nitrite on ebay, buy a bag or urea, break it to ammonia with lye and make AN and use lye again to get sodium nitrate and ammonia gas..

[Edited on 4-7-2013 by testimento]

woelen - 3-7-2013 at 22:59

Why all this difficult stuff? You can simply buy NaNO3 on eBay!

http://www.ebay.nl/sch/i.html?_trksid=p3907.m570.l1313&_...

I have used Dutch eBay for the search, but if you are in the UK or the USA you also have much lower shipping costs.

testimento - 3-7-2013 at 23:50

My friend ordered nitrates from a legitimate company. Once.

He sat in custody for 4 weeks because of that.

Fantasma4500 - 4-7-2013 at 10:26

Quote: Originally posted by Pok  
Quote: Originally posted by Antiswat  
ive seen KNO2 and KNO3 sold for same purpose on ebay de, as pökesalz.. im very sure that the KNO2 was cheaper..

Pökelsalz is ordinary table salt (sodium chloride) with only a tiny amount of sodium nitrite (0.4-0.5%). This is required by law. So nitrites are not that easy to get.

The KNO3 is often sold as pökelsalz in the chemicals section on ebay. The price is so high because of "bomb chemists" who need this stuff and will pay every price. Usually, it's very cheap (for people with a licence, e.g. butchers or farmers (fertilizer)).

I don't think that nitrites are so easily oxidized that O2 from the air will be sufficient to do this job reasonably fast. If you let your nitrite stand for years, yes. But not by bubbling air through a nitrite solution. I think H2O2 is the best solution.

[Edited on 28-6-2013 by Pok]


hmh.. i did see 2 kg of KNO3 of this pökelsalz, i supposed it was for different kinds of food where nitrates or nitrites are used

they dont state anything else but KNO3 and the respective E number so i doubt theres any impurities theyre aware of (NaCl +50%)

Random - 4-7-2013 at 10:32

Trading for the same amount of nitrate with someone has the highest yield.

DubaiAmateurRocketry - 4-7-2013 at 11:12

Well, nitronium nitrate.

http://en.wikipedia.org/wiki/Dinitrogen_pentoxide

Perchlorate oxidized to perchlorate

http://en.wikipedia.org/wiki/Dichlorine_heptoxide