Sciencemadness Discussion Board

KNO3 electralysis to nitric acid

symboom - 25-4-2011 at 23:27

first if i separate cells with a salt bridge of potassium nitrate
potassium hydroxide at the cathode and dilute nitric acid at the anode should form right?

also not sure if it will work but if ammonium chloride is separated anode from cathode by a salt bridge of itself hcl gas at the anode then gets absorbed into the water and ammonium form at the cathode and dissolves as so as its formed to i know if they are not separated ncl3 is formed have not found any thing if electrodes are separated by a salt bridge

woelen - 26-4-2011 at 00:44

With the electrolysis of KNO3 you are mostly right. At the cathode, however, there will be side reactions. The main reaction indeed is formation of KOH (and H2, escaping as gas), but the nitrate also will be reduced. This is not a clean reduction, a whole mess of reduced species will appear, among them being nitrite and ammonia.
This is not a practical method of making nitric acid. The use of the salt bridge will introduce large resistance between anode and cathode and this will reduce the useful current a lot. Besides that, long before you have a decent concentration of H(+) in the anode-part of the cell, the salt bridge will have to be replaced many times (ions are migrating through this, hydroxide and nitrite from the cathode cell move towards the anode and H(+) from the anode moves towards the cathode.

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NCl3 is formed anyway, regardless of having a saltbridge or not, when NH4Cl is electrolysed. At the anode, no HCl is formed, but Cl2 and at the cathode, H2 and ammonia is formed. The Cl2 reacts with ammonium ion and this can lead to formation of NCl3. You won't have a strong explosion from just a few minutes electrolysing a solution of NH4Cl, but doing so for a longer time may indeed lead to dangerous situations.

gnitseretni - 26-4-2011 at 06:06

Jesus F Christ, Symboom! At the very least TRY to write proper! :mad:

woelen - 26-4-2011 at 06:36

No need to call up Jesus. He probably doesn't read this thread and has more important things to do :P

But I agree with the message of gnitseretni. Some decent punctuation and the use of capital letters at appropriate places already helps a lot.

hissingnoise - 26-4-2011 at 06:58

Quote:
At the very least TRY to write proper!

I can never remember which is the pot and which is the kettle . . .:D

m1tanker78 - 26-4-2011 at 07:04

Quote: Originally posted by hissingnoise  
Quote:
At the very least TRY to write proper!

I can never remember which is the pot and which is the kettle . . .:D



(LOL) :)

Now, back to the topic. Symboom, what are you using for a power supply?

Tom

hissingnoise - 26-4-2011 at 07:14

Nitric acid cannot be obtained by electrolysing alkali nitrates, as woelen has already made clear . . .


condennnsa - 26-4-2011 at 07:20

yes it can
In this patent they melt KNO3 in aluminum vessel and electrolyze to K metal and NO2.

Attachment: US0517001_nitric_acid_and_metals_from_nitrates.pdf (151kB)
This file has been downloaded 440 times

ScienceSquirrel - 26-4-2011 at 07:25

You are never going to make nitric acid by electrolysis.
If you want fairly dilute acid ( 38% ) then I suggest you buy a litre of hydroponics pH down.
http://cgi.ebay.co.uk/CANNA-PH-DOWN-VEGETATIVE-PERIOD-1L-/27...
It is strong enough for quite a few reactions, making metal nitrates from oxides or carbonates, etc.

ScienceSquirrel - 26-4-2011 at 07:30

Quote: Originally posted by condennnsa  
yes it can
In this patent they melt KNO3 in aluminum vessel and electrolyze to K metal and NO2.


It is a patent from 1894!
Quite a few patents are really only dreams or staking a claim just in case there is something worthwhile there.
Making nitric acid at that time was really quite difficult so staking a claim to anything worthwhile was a good idea.

symboom - 26-4-2011 at 13:36

5 volt regulated power supply amps 1-20
well i did find some thing else ammonium nitrate reacts with magnesium hydroxide and calcium hydroxide
============
magnesium nitrate
330 °C (603 K) decomp.
---
calcium nitrate
Melting point
561 °C (anhydrous)
42.7 °C (tetrahydrate)

Boiling point
decomposes (anhydrous)
132 °C (tetrahydrate)

2 Mg(NO3)2 → 2 MgO + 4 NO2 + O2
2 Ca(NO3)2 → 2 CaO + 4 NO2 + O2

The absorption of these nitrogen oxides in water is one possible route way to synthesize nitric acid. Although it is inefficient, it does not require the use of another strong acid.
======
Copper nitrate can be used to generate nitric acid by heating it until decomposition and passing the fumes directly into water. This method is similar to the last step in the Ostwald process. The equations are as follows:

2 Cu(NO3)2 → 2 CuO + 4 NO2 + O2


256 °C (anhydrous, decomp)

Boiling point
170 °C (trihydrate, decomposes)


i have copper sulfate for sulfuric acid
so i could mix potassium nitrate and copper sulfate in a little water to form hno3
potassium sulfate and copper nitrate>
then then copper nitrate decomposing to no2 and o2
then lead into water to form hno3

Sedit - 26-4-2011 at 13:49

I have attempted this a few different ways in the past, mainly as a source of nitrites, but in the end the only thing I kept noticing was the strong smell of Ammonia being generated. I would not put much faith in electrolysis of nitrates to produce any acid of sufficient purity or strength. You will need to distill it and if one where to do that they may as well use Sulfuric and nitrates instead of producing the junk that will come about from this synthesis.

symboom - 26-4-2011 at 14:00

that is what i was thinking as so as i though if i just heat up nitrates but i need some glassware that wont shatter under the heat but my idea was to decompose nitrogen dioxide from as so magnesium nitrate in aluminum(which as i read passivated by nitric acid) tea kettle and condense them in to h2o2 since the water here is contaminated with iron.

[Edited on 26-4-2011 by symboom]

entropy51 - 26-4-2011 at 14:13

Quote: Originally posted by symboom  
that is what i was thinking as so as i though if i just heat up nitrates but i need some glassware that wont shatter under the heat but my idea was to decompose nitrogen dioxide from as so magnesium nitrate in aluminum(which as i read passivated by nitric acid) tea kettle and condense them in to h2o2 since the water here is contaminated with iron.

[Edited on 26-4-2011 by symboom]
Google "retort". You can find them for about $30.

If you just simply cannot bring yourself to distill sulfuric drain cleaner and some nitrate fertilizer, maybe this would work for you:
Quote: Originally posted by entropy51  
Back around the middle of the last century(!), I made respectably strong HNO3 by heating NaNO3 fertilizer, CuSO4 and grocery store alum as a dry distillation in a retort. I had found that prep in some 19th century chemistry book, it was not my invention. I haven't been able to find much mention of it in modern references; I think there may have been a historical article in J Chem Ed.


symboom - 26-4-2011 at 14:23

oh thanks that helps a lot i know i can just make sulfuric acid by electrolysis of copper sulfate just the heating part is a problem though i found out the hard way that Pyrex is not borosilicate glass anymore so there goes that shattered boiling nitrate and sulfuric acid so yeah ill defendant get a resort. i dont think aluminum is resistant to a mixture of sulfuric and nitric acid

[Edited on 26-4-2011 by symboom]

entropy51 - 26-4-2011 at 14:35

Here's a 250 mL retort for $36.50. Use a wire gauze with a pad, or a sand bath, between the retort and a flame. Set it up in a shallow plastic tray so that if it shatters the acid spill will be contained. Need I say goggles?

[Edited on 26-4-2011 by entropy51]

symboom - 26-4-2011 at 16:24

oh goggles i wear no matter what i am working with and gloves no losing fingers for me or chemical burns:D

[Edited on 27-4-2011 by symboom]

ScienceSquirrel - 26-4-2011 at 17:37

Quote: Originally posted by symboom  
oh thanks that helps a lot i know i can just make sulfuric acid by electrolysis of copper sulfate just the heating part is a problem though i found out the hard way that Pyrex is not borosilicate glass anymore so there goes that shattered boiling nitrate and sulfuric acid so yeah ill defendant get a resort. i dont think aluminum is resistant to a mixture of sulfuric and nitric acid

[Edited on 26-4-2011 by symboom]


James Joyce is reborn as a chemist to be sure, begorrah!

symboom - 27-4-2011 at 05:01

ScienceSquirrel i don't think i understand your British humor there

ScienceSquirrel - 27-4-2011 at 05:14

I draw your attention to Molly Bloom's soliloquy in the final chapter of Ulysses.
The whole chapter is eight sentences long with only two periods and no capital letters

http://en.wikipedia.org/wiki/Molly_Bloom%27s_Soliloquy

symboom - 27-4-2011 at 05:24

Ulysses makes me think of homers the Odyssey with Odysseus the main character. which i had to read in HS anyways a bit off topic.

jamit - 27-4-2011 at 05:54


Gnitsertni...yes I agree with you that people need to write up a proper report but equally there is no need to bring Jesus into the equation and use his name as a cuss word.

blogfast25 - 27-4-2011 at 07:15

Synboom seems intent on finding long, complicated and possibly dangerous ways of synthesising OTC materials. I’m not sure what the ‘boom’ in his screen name stands for but I doubts if it’s related to ‘bonanza’ or’ peak’.

He’s also clearly intent on getting a prize for the worst composed posts and that takes some doing in this madhouse. His reaction scheme for ‘electrolysis free chlorate’ elsewhere kind of took the biscuit, I quote:
Quote:

1. 2Ca(0H)2 + 2C12 -» Ca(C10)2 + CaCl2 + 2H20
2. UHsO + 4Cl2-> UH0C1 + UHC1
3. Ca(C10)2 + UH0C1 -» Ca(C103)2 + UHC1
k. UCa(0H)2 + 8HC1-* UCaCl2 + &E^)
5- 6ca(0H)2 + 6Cl2-» Ca(C103)2 + 5CaCl2 + 6Hj>0
6. Ca(C103)2 + 2KC1 -» CaCl2 + 2KC103


I’ll give him the benefit of the doubt and assume he just wants to learn about chemistry, something to be encouraged on a (predominantly) chemistry forum but instead of trying to create complicated reaction schemes for simple chemicals that seem plucked straight out of an 18th century chemistry handbook, he should perhaps get a little stockpile of base chemicals and do some simple synthesis of simple stuff he’s probably never heard of before and get some job satisfaction.


Bot0nist - 27-4-2011 at 07:44

Quote: Originally posted by jamit  

Gnitsertni...yes I agree with you that people need to write up a proper report but equally there is no need to bring Jesus into the equation and use his name as a cuss word.


*off topic*


[rant]
Jamit, I know he offended your theological sensibilities by using your Lord's name in vain, but this is the internet and not all people share your faith or reasoning. I am quite sure that he meant no direct insult to you or other pious members of the board. He was simple using a common colloquialism for impact. It is my belief that projecting your own moral and religious values onto another is equally needless.
[/rant]
;D

symboom

symboom - 27-4-2011 at 09:57

actually the boom i thought of was my favorite boombox that ive had for a long time even if is out dated. the screen name is more just as i just really love music and dance too and no it really does not have any thing with explosions in more of a pyrotechnic person and metallurgy blacksmiths and the arts.

yeah your right i have said some crazy ideas i like to try different approaches just for the experience and to answer your question
i have done the normal approaches first but i like to experiment maybe a little more of other possibilities to make the same thing maybe a different way. even if it is really complicated i got to at least try and if i fail at it Ive learned from it.

[Edited on 27-4-2011 by symboom]

gnitseretni - 27-4-2011 at 10:26

Quote: Originally posted by symboom  
actually the boom i thought of was my favorite boombox that ive had for a long time even if is out dated. the screen name is more just as i just really love music and dance too and no it really does not have any thing with explosions in more of a pyrotechnic person and metallurgy blacksmiths and the arts.

yeah your right i have said some crazy ideas i like to try different approaches just for the experience and to answer your question
i have done the normal approaches first but i like to experiment maybe a little more of other possibilities to make the same thing maybe a different way. even if it is really complicated i got to at least try and if i fail at it Ive learned from it.

[Edited on 27-4-2011 by symboom]


WOW, I see a few dots in there :o

Maybe next year he'll use commas as well :P

[Edited on 27-4-2011 by gnitseretni]