chemoleo
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Electrolysis of Nitrates
Had this conversation with someone recently, on the electrolysis of salts in general.
Well, for instance, the electrolyis of chlorates gives perchlorates, sulphates give peroxo sulphate, but how about nitrate?
Obviously there is no higher oxidation state than 5, so what could happen? I am tempted to think nothing, but the electrolysis of water itself, to H2
and O2.
I.e. I take a saturated solution of NaNO3, and electrolyse this.
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BromicAcid
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Well, there are pernitrates but they are somewhat unstable.
O
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N-O-O-
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O
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Saerynide
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Why do text books and teachers all say that nitrates, sulphates and chlorates cant be oxidized by electrolysis when things actually happen to them
when you do so?  Im all confused now 
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hodges
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Electrolysis of KNO3
I once electrolysed a solution of KNO3 in a cell with two carbon rods separated by a membrane. After a while (once the solution had a pH > about
13.5), I got a distinct smell of NH3 at the cathode.
I've also heard that it is possible to get nitrates (with small yield) by electrolysing ammonium salts. If anyone wants to try this, I would NOT
recommend using the chloride .
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The_Davster
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| Quote: | Originally posted by Saerynide
Why do text books and teachers all say that nitrates, sulphates and chlorates cant be oxidized by electrolysis when things actually happen to them
when you do so? Im all confused now |
Teachers lie.
Every year of chem I have taken I always find out that of what I took last year about 10% of it was a lie
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darkflame89
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Won't the electrolysis of nitrate salts gives nitric acid at the anode???
Ignis ubique latet, naturam amplectitur omnem.
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hodges
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| Quote: | Originally posted by darkflame89
Won't the electrolysis of nitrate salts gives nitric acid at the anode???
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Yes, but its hard to get much concentration (pH less than 0.5 say, which would only be 0.3M). Apparently some mixing goes on through the membrane.
Possibly would work with a special membrane. You might be able to distill the HNO3, but presumably if someone has a distilling apparatus they can
probably already make HNO3 using the nitrate and sulfuric acid.
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axehandle
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Membrane.
Has anyone got any idea how such a membrane could be constructed or bought?
I've got 50kg of ammonium nitrate and about 60 kg of potassium nitrate, and an unlimited supply of electricity. It's nice to live only 50
kilometers from a nuclear plant.
[Edited on 2004-3-30 by axehandle]
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darkflame89
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Got this recent idea, dunno if it works.
React MgO with NH4NO3 to get the ammonia and the Mg(NO3)2
Then, take the Mg(NO3)2 and heat it to get the NO2 gas. You then dissolve it in water to get nitric acid.
Then you could probably concentrate it by electrolysis.
Ignis ubique latet, naturam amplectitur omnem.
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Esplosivo
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If NO2 is dissolved in water it gives a mixture of nitrous and nitric acids, not only nitric acid.
darkflame89, what do you mean by concentrating by electrolysis?!
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rikkitikkitavi
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MgO doesnt hydrolyse easily to Mg(OH)2
Neither is it easy to react
Mg(OH)2 + 2 NH4NO3 => Mg(NO3)2 + 2 NH3 (g) due to the low solubility of Mg(OH)2.
Try with CaO instead.
Nitric acid can not be concentrated by electrolysis since it decomposes into water, NH3, NH4+ , NOx, e t c,
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darkflame89
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But i can hardly find CaO in Singapore, unless i can convert CaCO3 to CaO
Ignis ubique latet, naturam amplectitur omnem.
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KABOOOM(pyrojustforfun)
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NO3 radical
from <a href="http://bcis.pacificu.edu/~polverone/copae.html">The Chemistry of Powder and Explosives</a>:
<blockquote>quote:<hr>Ohman (532. Elektrochem., 42, 862 (1936); Svensk Kemisk Tid., SO, 84 (1938)) in Sweden has developed an ingenious
electrolytic
process for the production of nitric esters direct from ethylene.
The discharge of the nitrate ion (NO<sub>3</sub><sup>-</sup> at the anode liberates the
free nitrate radical (NO<sub>3</sub> which in part combines directly
with
ethylene to form nitroglycol.
H<sub>2</sub>C=CH<sub>2</sub> + 2NO<sub>3</sub> <s> ></s>
O<sub>2</sub>NO-CH<sub>2</sub>-CH<sub>2</sub>-ONO<sub>2</sub>
Another portion of the free nitrate radical apparently reacts with
itself and with water as indicated below, and the oxygen which
becomes available enters into the reaction with the consequent
formation of dinitrodiglycol.
2NO<sub>3</sub> <s> ></s> N<sub>2</sub>O<sub>5</sub> + [O]
N<sub>2</sub>O<sub>5</sub> + H<sub>2</sub>O <s> ></s>
2HNO<sub>3</sub>
H<sub>2</sub>C=CH<sub>2</sub> + [O] + 2NO<sub>3</sub> <s> ></s>
O<sub>2</sub>NO-CH<sub>2</sub>-CH<sub>2</sub>-O-CH<sub>2</sub>-CH<sub>2</sub>-ONO<sub&g
t;2</sub>
A platinum gauze anode is used. It is immersed in an acetone
solution of calcium nitrate which is kept continuously saturated
with ethylene which is bubbled through in such manner that it
sweeps over the surface of the platinum gauze. An aluminum
cathode is used, in a catholyte consisting of a nitric acid solution
of calcium nitrate, and the cathode compartment is filled to a
higher level since the liquid moves into the anode compartment
as the electrolysis progresses. After the electrolysis, the cathode
liquid is fortified with nitric acid for use again. The anode liquid
is neutralized with slaked lime, and distilled in vacuum for the
recovery of the acetone, and the residue, after the removal of
calcium nitrate, washing, and drying, consists of a mixture of
nitroglycol and dinitrodiglycol and is known as Oxinite. Dynamites
made from Oxinite differ but little from those made from
nitroglycerin.<hr></blockquote>
now instead of using ethylene why not combine it with a kolbe reaction?!!
eg electrolysis of NaNO3 and sodium acetate to get methyl nitrate at anode and hydrogen at cathode major byproduct of anode would be ethane but also
traces of methanol and oxygen
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MadHatter
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CaO
CaO has a higher solubility than MgO. Even given that, it takes quite some time for it to
react with NH4NO3. Reacting MgO would probably push the limits of your patience.
From opening of NCIS New Orleans - It goes a BOOM ! BOOM ! BOOM ! MUHAHAHAHAHAHAHA !
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rikkitikkitavi
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Actually, CaO reacts immediately with water to
Ca(OH)2 . The reaction can be slow or fast, depending on particle size (surface).
MgO , if not heated up to 1500 C or so, reacts much more slowly, taking up to days to hydrolyze. If heated to about 1500 C (dead burned) crystal
structure changes and it is almost inert (magnesia)
however, I will take back that Mg(OH)2 doesnet react with NH4NO3(not that it matters much six months later).
Mg(OH)2 does react with ammoniumsalts.
/rickard
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chemoleo
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Electrolysis of nitric acid
For some reason, I discovered this document on the electrolysis of nitric acid, which I never noticed before. I hope noone else posted it somewhere, I
don't even know how I obtained it.
Anyway - it's actually quite interesting, and confirms hodges observation - the electrolysis of HNO3 causes reduction of the
nitrogen, not oxidation. That is, it depends on the cathodes being used, Pt electrodes and a diaphragm produce nitric oxide, copper cathodes ammonia,
and polished zinc 46 % hydroxylamine (next to ammonia!!)
So essentially, without electrode separation, the electrolysis of HNO3 with Zn cathode should produce ammonium nitrate and hydroxylamine nitrate!
I thought this is too interesting to leave this unmentioned.
Attachment is as .doc, & large, might change this later. But have a look for now 
[Edited on 25-3-2005 by chemoleo]
[Edited on 16-12-2007 by chemoleo]
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Contrabasso
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Ntric acid by electrolysis
Just read somewhere else about a proposal to synthesise nitric acid from nitrates in solution. Also I found a book in the site library that suggests
it is both possible and practical.
Has anyone done it?
Could I electrolyse KNO3 and get HNO3 + K...
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not_important
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It's a form of electrodialysis, using cation and anion selective membranes.
http://www.agc.co.jp/english/chemicals/ion-maku/selemion/sel...
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Pulverulescent
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| Quote: | Originally posted by Contrabasso
Has anyone done it?
Could I electrolyse KNO3 and get HNO3 + K... |
Look in Hale's "Manufacture of Chemicals by Electrolysis" for the old "Nodon Process"!
It claimed to produce HN03 from alkali-nitrates in peat, but the mechanism is a bit unclear.
P
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chemoleo
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Merged your new thread, contrabasso, with this one. It should answer some questions.
As indicated, your nitrate salt will get reduced unless you employ selective anion membranes.
Never Stop to Begin, and Never Begin to Stop...
Tolerance is good. But not with the intolerant! (Wilhelm Busch)
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Pulverulescent
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Contrabasso, all things considered, IMO, producing HN03 from KN03 electrolytically looks so fraught with difficulties it makes distillation from H2S04
look like child's play.
P
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JohnWW
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Elerctrolysuis o nitrates, at a suffuiciently high voltage, would produce either pernitrates, NO4-, or else nitrogen peroxide, NO3 or N2O6.
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