Sciencemadness Discussion Board - Nitric Acid Synthesis

Nitric Acid Synthesis

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Alain123 - 16-6-2004 at 15:35

I know this has been posted before, and I have done a search on it. I have not done anything to do with chemistry in one year, but now I want to continue to learn about it. Many topics that have been made about a synthesis of nitric acid are complicated, and someone like me would not understand it. I have also searched on the internet for different syntheses for nitric acid, but they don't sound right. I am looking for a simple explanation that is the least dangerous. I also do not have much equipment. I have one good 125mL pyrex flask, a cheaper but larger 250mL flask. I have rubber stoppers taped with teflon and a 9 inch glass tube connecting the two flasks, through the stoppers. I don't think the glass tubing that I have will suffice because of the fact that it is so short, and the width of the hole going through the tube is too small. Other apparatus that I have is a glass eye dropper, a 100mL beaker and a glass stirring rod. I am going to buy the chemicals once I find a synthesis for nitrc acid that I am comfortable using.

Thanks a lot.

Darkfire - 16-6-2004 at 16:03

Two ways

Alain123 - 16-6-2004 at 19:01

How do I know how much potassium nitrate to put in the H2SO4 (and how much?)? I would also like to say that I want to make a very small amount of nitric acid as this will be my first time if I decide to make it, and I want to be safe. When mixing the potassium nitrate and sulphuric acid, do I mix them up and then quickly put the stopper back on which is connected to the other flask through the tubing? I'm assuming that the reaction between the two chemicals will result in nitric acid gas, right?

Sorry for all the questions, but I just want to make sure.

sanity gone - 16-6-2004 at 20:23

I ran some quick numbers and to make a 50% conc of HNO3 I believe you will want to use 36.0gKNO3 and 50.0ml of conc. sulfuric acid. In 50ml of water I believe the yeild will be a 50% concentration of nitric acid.

I figure with 50ml of sulfuric you have 0.6mol of the acid in soln. Now to use up all the acid you would need 1.2 mol of potassium nitrate. You could only dissolve that much in 333ml of water. So I used 36 in 100ml becuase that is the water solubility of KNO3. So in this situation, obviously KNO3 is limiting. We now have 0.36mol of KNO3. 0.36 mol of KNO3 will yeild 7.2 mol of nitric acid in 50ml of water. Conc nitric is 14molar.

Finally, if you do make the acid do a qualative analysis on it. Take about 10 ml of your acid and add 7.5g Ag. Then take the soln and add 40.9g NaCl. You should get a percipitate. Mass the solid out and then run the numbers.
I hope my math skills still hold up

[Edited on 17-6-2004 by sanity gone]

Alain123 - 17-6-2004 at 08:16

I have another question, do I really need a burner? Because I don't have one..

Darkfire - 17-6-2004 at 11:09

Yes you need a source of heat.

Saerynide - 17-6-2004 at 21:57

Use the stove

Esplosivo - 18-6-2004 at 06:47

Or else try using an alcohol burner. Will not provide the same heat but the evolution of nitric acid might occur, at slooowwer rates.

Marvin - 18-6-2004 at 10:44

Darkfire, the first method will work really badly. The receiving container is in thermal contact with what is being distilled and the distillate will boil at a lower temperature. What happens practically is you form a little nitric acid which then refluxes itself to death. Raising the container off the bottom would help, but its basically a waste of time.

Alain123 - 18-6-2004 at 12:44

How long will my glass tubing need to be? What about the width of the hole?

Darkfire - 18-6-2004 at 13:20

It depends, longer better.

Yeah i forgot to show it sitting on a stand my bad. Its actualy a very good method, Brainfever has had great sucess like that. It a quick drawing, chem out brainfever site for the real setup and explantion.

Proteios - 18-6-2004 at 14:03

distillation path length here is almost irrelvant... I think HNO3 boils about 80 C.... H2SO4 about 350....

Proteios - 18-6-2004 at 14:15

.....one of my dad friends had a vac. distillation of HNO3 blow up in his face....the pain was such that he was totally incapacitated......had there not been people to hand in the lab, who knew what he was doing, his injuries would have been much more severe... probably life threatening. The safety specs. certainly saved his eyesight.
HNO3 is nasty stuff..... Hot H2SO4 is nasty stuff......Hot HNO3 is really nasty.... make sure you have contigency plans if things do not follow the game plan. I would at minimum use a full face visor.

Darkfire - 18-6-2004 at 14:29

Dont scare the poor kid... As long as he follows saftey precautions hell be ok, this isnt exactly vacume distilling.

Cyrus - 18-6-2004 at 22:02

I really think that the beaker in a beaker / plastic baggy method will give you low yeilds, but it is quick and easy.

The size of your glass pipe just affects the time it takes, however, it might be wise to cool the pipe somehow- like a liebig condenser with a water jacket, you get the picture. If not, I'll have to post pics. But I don't know how. Can someone show me? Anyways, I tried distilling water in a 30 cm glass tube setup with no cooling, and it just came out as steam at the other end. Cooling solved that one, might help for nitric acid, is good for general distillation anyways. If you need help figuring out how to cool the pipe, ask, but I'm to tired to explain my method in detail right now.

Proteios - 19-6-2004 at 08:41

Now that i come to think about it.... most plastics are eaten by HNO3..... even more so HNO3.

For the experiment shown it needs to be a semi elastic film too.

froot - 19-6-2004 at 08:46

Proteus, do you by any chance know why that distillation setup blew up? Was it something he did or did it just suddenly go off? Seems uncharacteristic to me.

Saerynide - 19-6-2004 at 09:01

Quote:

Originally posted by Proteios
Now that i come to think about it.... most plastics are eaten by HNO3..... even more so HNO3.

For the experiment shown it needs to be a semi elastic film too.

Use a martini glass with the glass stem part broken off. Seal whats left of the martini glass to the container with teflon tape just incase.

axehandle - 19-6-2004 at 09:41

Quote:

Use a martini glass with the glass stem part broken off. Seal whats left of the martini glass to the container with teflon tape just incase.

That's ingenious. For a larger cone, I suppose multiple layers of Al foil could be used --- Al is mostly resistant to cold HNO3, right?

Esplosivo - 19-6-2004 at 11:00

Yes right axehandle. The Al forms the outer oxide layer by oxidation due to the HNO3, which is unreactive. It is said to be passivated if I remeber correctly.

axehandle - 19-6-2004 at 11:41

Once I used a "plastic-reinforced Al foil inverted cone" to destill CH3CH2OH. Instead of having a beaker inside the large bucket, I installed a "V"-shaped sloped tray made of Al plate so the distilled ethanol could drip into that and then run out of the bucket through the tray (does this make sense?).

The inverted cone was filled with water and ice cubes, and I heated the bucket with a huge homebuilt alcohol burner. This was a long time ago, I was only 15, but I got what I think was 70% ethanol from it.

The_Davster - 19-6-2004 at 12:43

Kinda makes sense, I think. Are you saying that under the inverted cone there was some sort of trough that would carry the distillate outside the boiling bucket. Instead of having a beaker there?

axehandle - 19-6-2004 at 12:53

Exactly. A "V" shaped trough, slighly sloped, carrying the destillate outside. It worked perfectly for ethanol.

[Edited on 2004-6-19 by axehandle]

The_Davster - 19-6-2004 at 13:00

What were you doing your distilling in? When I hear bucket I think plastic... And if it was glass how did you make a hole in it for the trough?
hmm, I just reread some of it and did you make the reaction vessel out of aluminum foil?

If I am not completly confused you made a still out of tinfoil, now thats cool

Proteios - 19-6-2004 at 13:05

the distillation that blew up.... i think was down to stressed glassware.... this is one of my dads collegues.... when they were working in a lab... so its maybe 40 years ago now. I know it was a vacuum distillation... probably in a custom made kit.... propably soda glass..... long before people had a good idea of how to relieve stress in glassware by anealing (unlike todays glass blowing with programable anealing ovens). Above 400 ml you can get a reasonable bang.... and quite a lot of energy out of glassware failure (under vaccum). Here of course... only enough energy is required to splash the acid around a bit!

axehandle - 19-6-2004 at 13:17

Quote:

What were you doing your distilling in? When I hear bucket I think plastic... And if it

A galvanized steel bucket, with 10 layers of aluminum foil strapped to the top, with a lead weight in its middle to make a sloped cone.

Quote:

was glass how did you make a hole in it for the trough?
hmm, I just reread some of it and did you make the reaction vessel out of aluminum foil?

If I am not completly confused you made a still out of tinfoil, now thats cool

Not tinfoil. Al foil and a power drill and some McGyverism, but it worked....

If I had a scanner, I would draw a picture, but imagine that where the drops fall down, there is a V shaped through leading out through the side of the bucket, slighly sloped. Hardly rocket science, but I was only 15....

[Edited on 2004-6-19 by axehandle]

vulture - 19-6-2004 at 13:21

Al is only resistant to HNO3 vapour when it's reasonably pure. That's where the trouble starts with commercial foil, even more because it's usually based on a PE foil.

Esplosivo - 19-6-2004 at 23:16

When we are talking about vacuum distillation of nitric acid what should the pressure in the apparatus be? Is 65 mbar sufficient? Thanks

Proteios - 20-6-2004 at 08:36

65mb give or take 1/10th of an atmosphere.... Yeah.. that aint too bad a vacuum.... i would expect the HNO3 to distill pretty quickly at about 40ish C.

Certainly with the range of a hairdryer!

[Edited on 20-6-2004 by Proteios]

Esplosivo - 20-6-2004 at 09:07

Thanks Proteios. I intended to use a water filter pump. I found one better now reducing the pressure of the distillation app to approx. 20 mbar.

Marvin - 20-6-2004 at 09:26

Water aspirator will depend a lot on the temperature and pressure of the water from the tap. 20mbar is probably very close to the water vapour pressure.

Esplosivo - 20-6-2004 at 09:57

As seen on catalogue it says it can attain 20mbar with a water pressure of 1bar. There are others which can attain even lower pressures with a water pressure of 1.4bars - reducing the pressure of the app up to 16 mbar.

Ooo, btw thank you all for the help.

[Edited on 20-6-2004 by Esplosivo]

Possible Alternate Pathway

Chemtastic - 24-6-2004 at 13:21

Instead of distillation, wouldn't this reaction work?

HCl(aq) + AgNO3(aq) --> AgCl(s) + HNO3(aq)

243g of AgNO3 are soluble in 100g of H2O, but only 0.00019g of AgCl are soluble in the same volume of water.

Marvin - 24-6-2004 at 13:47

If the HCl is a solution in water, and the AgNO3 is a solution in water, you wont get very strong nitric acid at the end.

Recycling the silver is a pain, needed because silver is expensive and silver nitrate is more expensive. Producing silver nitrate uses up nitric acid and you end up making dilute nitric acid from dilute nitric acid.

Distilling from silver nitrate is a good way to remove trace chloride from nitric acid though.

further concentration

demolitions - 1-9-2004 at 19:24

if its not too much trouble, could someone explain to a true chemistry novice how to further concentrate 70% nitric acid to at least 90%? seems like trinitrotoluene and PETN can be produced with nothing less... and all this distillery talk seems to be in code

vulture - 2-9-2004 at 01:08

Read the thread mister.

If it's code for you, educate yourself.

Don't be a lazy fuck. I personally detest lazy fucks.

[Edited on 2-9-2004 by vulture]

demolitions - 2-9-2004 at 15:27

sorry, just looking for a shortcut
maybe if I had the time to write over 1300 posts and sit in my basement with a tinkertoy chem set... your waffling your life away belgian fucker
by the way, i'm sure you have other people to insult seeing as how this is barely the least intelligent question asked on this forum

fvcked - 2-9-2004 at 16:32

Your asking to be spoon fed. And what I say to people asking to be spookfed is "spoon feed your ass!". You are not smart enough to do ANYTHING other than baking soda and vinegar. Hell I wouldnt trust you with toilette opener. Go bury yourself in a chemistry book, then come back!

(I like to flame)

Magpie - 2-9-2004 at 18:32

Is this right: you've got the time to make TNT and PETN but not the time to learn about the distillation of nitric acid?!

Vulture doesn't need anyone to stick up for him - but he is doing more than playing with a chemistry set - he happens to be a chemical engineering student and that is not a trivial pursuit. I personally don't see how he manages to do that and make over 1300 posts, plus discipline and dispose carcasses like yours. He must indeed love his work.

The Ed - 2-9-2004 at 20:17

Yeah dude, seriously. If you didn't notice, Vulture is a mod. Repent as soon as you read this and maybe he'll let you live. He might prefer seeing you get flamed by all of us than banning you anyway.

One way to further concentrate 70% nitric acid is to mix it with concentrated(i'd say 98%) sulfuric acid, then distill it at 80 degrees C. The water will stay with the sulfuric acid. That's all the info you'll get from me. But if you want to be able to make PETN and TNT you'll need to understand enough basic chemistry to break our mysterious code, otherwise you might lose a limb or even your life rather than just your forum membership.

But... lmfao. "your waffling your life away belgian fucker." Sorry Vulture, I get a kick out of that.

[Edited on 3-9-2004 by The Ed]

vulture - 3-9-2004 at 00:29

Demolitions has been demolished.

Now back on topic.

Centimeter - 11-9-2004 at 19:24

H2SO4 is quite expensive where I live, so its use in HNO3 production is a pain. Thus I shy away from using nitrate salts to produce HNO3 as the sulfuric acid can't be recycled. Thus I am left with concentrating 68% HNO3. This way I don't even have to use sulfuric acid as no protonization is neccesary. I was wondering if anybody had a good method of producing HNO3 by bubbling NOx through water. I am prety sure that this could generate 68% HNO3. Alas, how to produce the NOx gas. Does anybody know of a cheap and easy way of producing the NOx? I know that nitrate salts can be decomposed through heating, but this seems to involve farely large temperatures. I was thinking that perhaps the reciprocated haber process would be a good option, however this would invovle some complex equipment. Any thoughts? On another note, I was wondering if I could use HCl as a substitute for H2SO4 in nitrations/HNO3 production from nitrate. The HCl would easily produce nitronium. One could then use all sorts of chemicals to take the water out of the reaction; magnessium nitrate comes to mind.

JohnWW - 11-9-2004 at 20:49

As for a possible substitute for H2SO4 in nitrations of aromatics: I think the only definitely viable alternatives would be perchloric acid, HClO4, and hexafluorophosphoric acid, HPF6. Others which just might work could be periodic acid, perbromic acid, selenic acid, tetrafluoroboric acid, or phosphoric acid. Permanganic acid and chromic acid, and other high-valent transition-metal acids, would be suitable if they did not decompose, or oxidize organic compounds, so readily. The reaction conditions may result in oxidation of the Cl- in HCl by nitrate, if HCl is used.

In any case, it has to be a stronger acid than HNO3 and one which resists oxidation, in order for the latter to accept a proton. Because the electrophile in nitration is the nitronium ion, NO2+, formed by such protonation of HNO3, the only way you could get away without using such a stronger acid is by using a nitronium salt - which in any case exist only of the strongest acids, i.e. NO2ClO4, NO2PF6, (NO2)2SO4, stronger than nitric acid.

BTW I have heard somewhere of the tetrafluoroammonium ion, NF4+, having also been produced in combination with the same acid anions, analogous to NO2+. However, it cannot
be used to produce compounds exactly analogous to nitro-compounds, retaining all 4 fluorines, because pentavalent N cannot have more than 4 covalent bonds besides an ionic bond with the positive charge on the N. But a compound like N-trifluorophenylammonium perchlorate, [C6H5-NF3]+[ClO4]-, should be possible, although it does not show up in a Google search.

John W.

neutrino - 12-9-2004 at 06:04

Calcium nitrate, available as a fertilizer, decomposes to CaO, NOx, and O2 at modest temperatures (~200*C, I think). To produce nitric acid, the following reactions are utilized:

3NO2 + H2O ->2HNO3 + NO

NO + 1/2 O2 -> NO2.

[Edited on 12-9-2004 by neutrino]

Centimeter - 12-9-2004 at 08:55

I was under the impression that it took somewhere around 500*C to decompose calcium nitrate. This was most likely what I was going to go with, but 500*C uses a lot of energy. I think the most practicle would be to use the haber process. Does anybody have some good plans for such a setup?

neutrino - 12-9-2004 at 17:15

I'm not really sure of the temperature needed. Are you sure you want to use the Haber process to make ammonia? The reason it's used industirally it because it's cheap and east to do with vast amounts of equiptment (about a small city's worth--the factories are huge), but on a smaller scale, it would be impossible. Ungodly pressures (~200 atm) would be the main problem. If you want ammonia, there are better ways of getting it. Get it from the store or decompose some ammonium sulfate fertilizer.

Centimeter - 12-9-2004 at 18:43

I guess so, but it just sounds like a realy interesting procedure. Anyhow, I figured out what I am going to do. I have acess to 15.5-0-0 fertilizer. I am going to convert it all to calcium nitrate by adding Ca(OH)2 and boiling. I am then going to mix a solution of calcium nitrate with iron sulfate and filter out the subsequent calcium sulfate. This should produce iron (III) nitrate which decomposes at around 100*C. Does anybody know the ratio of NH4NO3 to Ca(NO3)2 in 15.5-0-0 fertilizer? I wouldn't want to add too much calcium hydroxide now would I.

JohnWW - 12-9-2004 at 18:59

I remember reading somewhere that, before deposits of niter (mostly KNO3 with some NaNO3) were discovered in the rainless north Chilean desert, and before the Born-Haber process was developed for ammonia along with methods for oxidation to nitrate, nitrates for use in gunpowder were obtained from urine and animal manure. Of course, it was not very pleasant for the workers.

John W.

neutrino - 13-9-2004 at 13:28

Pure Ca(NO3

2 would be 17.1-0-0, meaning that your fertilizer probably has a bunch of chalk/other binders in it and isn't pure calcium + ammonium nitrate. What I'd do is to dizzolve the the stuff in a generous amount of water, filter out the insoluble junk, then keep adding Ca(HO)2 until it stops dizzolving. Filter and boil down the solution to obtain crystals.

If anyone is interested in nitre beds, there was a thread on EW Here.

[Edited on 13-9-2004 by neutrino]

Ratio

MadHatter - 14-9-2004 at 08:30

Centimeter, if I'm not mistaken, that formula for the double salt appears as:

5[Ca(NO3)2] * NH4NO3 * 10[H2O]

This is for the 15.5-0-0 fertilizer. The stuff I get is always coated with that
pain in the ass wax so I place it in a filter of several paper towels and run
ice water through it until only the wax remains in the filter. Then I treat
the solution according to my needs.

According to both of my CRC manuals, the melting point of Ca(NO3)2,
NOT the hydrated version, is 561 C. Neither manual lists a decomposition
temperature.

The decomposition temperature of the tetrahydrate depends on which
version of the CRC you trust.
Tetrahydrate formula: Ca(NO3)2 * 4[H2O]

The CRC 52nd Edition(1971-1972) says it decomposes at 132 C.

The CRC 81st Edition(2000-2001) says it decomposes at 40 C.

Neither CRC manual says what it decomposes into. It's possible that
it decomposes into the anhydrous version and water vapor but until I
have a more detailed source of information, I can't say for sure.

rikkitikkitavi - 18-9-2004 at 08:51

Ca(NO3)2 starts to decompose at 500 C , above melting point the decomposition is vigorous acording to Gmelin. There is patents describing a process for this decomposition, since the CaO formed hardens teh melt and makes heat transfer tricky.

Long before this water is of course given off, and any NH4NO3 is decomposed.

spudmann-annm1 - 12-10-2004 at 06:22

I'm new here, can I ask a few questions. First does the glassware need to be from DURAN glass, secondly can you make 95% nitric acid, by putting 70% nitric in a dessicator, or can you destill (or distill, don't know how you say) 70% nitric to 95% nitric acid?

--------------------------------------------------"
READ the thread and educate yourself on the basic principles of chemistry before you post. Check the thread about "The book on chemistry

[Edited on 12-10-2004 by vulture]

Theoretic - 13-10-2004 at 13:32

"spudmann-annm1"
The username seems a bit dodgy to me. I think if you look carefully, you notice "annm" - yes, ANNM. Seems like another kewl to me... although I might be wrong.

[Edited on 13-10-2004 by Theoretic]

Polverone - 13-10-2004 at 21:42

Maybe so, but here we do not hunt for <strike>witches</strike> <strike>communists</strike> kewls. Rather we let people speak until/unless they prove incapable of communicating productively.

Edit my username

spudmann-annm1 - 14-10-2004 at 05:51

Can you please edit my user name to spudmann1, so that the other members won't get nervous, I'm not an anarchist if you mean that, i just yet don't know how to detillate things, but I am like everyone an expert in a specific field. If you think this post or my membership is impropriate just exclude my membership.

What is a kewl?

[Edited on 14-10-2004 by spudmann-annm1]

neutrino - 14-10-2004 at 13:28

Your username cannot be edited. You can, however re-register under a different name. You've only made 3 posts, so you wouldn't be loosing a significant number anyway.

I'm sure that there are those who can define what a 'kewl' is much better than I can, but kewls are usually morons who read the anarchist or terrorist handbooks or some other crapbook, try stuff out not knowing anything about it, and are, to varying degrees, brain-dead.

TROLL

MadHatter - 14-10-2004 at 20:23

GODDAM ! Is that a troll I'm smelling ?

Theoretic - 15-10-2004 at 13:06

Sorry, meant no offence.

What TROLL?

ADP - 17-5-2008 at 17:10

Just did a vacuum distillation of HNO3, pics soon to follow. I'm pretty excited considering it's about 90-95+% HNO3

crazyboy - 17-5-2008 at 17:36

Quote:

What is a kewl?

Someone purely interested in destruction, explosions, mischief or causing harm to living things or property.

Quote:

What TROLL?

I'm not sure if this is a question but if it is here's an answer, a "troll" is a term usually used on totse (generally considered a kewl forum) to describe a thread or post that is fictitious and is meant to deceive or joke with other members.

Example: I have an intense sexual attraction to fruits especially citrus is this normal?

Quote:

Just did a vacuum distillation of HNO3, pics soon to follow. I'm pretty excited considering it's about 90-95+% HNO3

Can't wait to see the pictures I have been meaning to synth some HNO3 but as of now I don't have a distillation setup and am too poor to afford one.

ShadowWarrior4444 - 17-5-2008 at 17:42

Quote:

Originally posted by crazyboy

Quote:

What is a kewl?

Someone purely interested in destruction, explosions, mischief or causing harm to living things or property.

Quote:

What TROLL?

Four years later. *smirk*

I am certainly looking forward to photos of the apparatus used in the vacuum distillation. And perhaps a cursory writeup of the reagents involved. Also, whether you used a substitute vacuum grease!

HNO3 Vacuum Distillation

ADP - 17-5-2008 at 19:23

Alright guys so after coming home for the summer and rummaging through my chem supply, I decided to synthesize some HNO3. The following "reagents" were used:

Liquid Lightning (H2SO4 Source)
KNO3 (Nitrate Source)

Because my last scale is broken (new one on the way), I measured out 500mL of liquid lightning and basically added nitrate salt until the solution was saturated with KHSO4, which makes it hard to stir. I added a small amount of distilled water (50mL or so) to make the solution easier to stir and so I could add a little more nitrate - the excess H2SO4 will keep it from being distilled over and it will make the solution boil more smoothly.

The following photos are an account of my project:

Here is my distillation setup. It is all 24/40 ground glass. I used an oil bath to maintain temperature at 60dC at all times - my solution boiled vigorously at this temperature without decomposition.

This is my mixed acid solution for distillation.

After about 25 minutes of distillation...

My final yield - I final run time was about 1hour 10minutes

My vacuum aspirator - this baby does WONDERS

Notes:
There was about 500mL mixed acid at time of distillation.
Temp was held constant at 60dC for 1hr10min.
The distillate stoped coming over when the mixed acid started a runaway "foam" production under vacuum. To prevent this from coming over I immediately killed the vaccuum. Another attempt was made to boil the solution again but the foam started rising again... I still got a good yield.
I have not measured the volume of the yield yet but think it is about 200mL

Possible improvement: Use NH4NO3 as NH4HSO3 is more soluble in acid.

Purity test:
I plan on (when my new scale arrives) doing a density test on exactly 1cc of the acid to determine purity. I dropped a penny in a small amount of the acid and it intensely reacted making a cloud of NO2 and totally dissolving the penny - I was impressed...

Any thoughts guys?

zeppelin69 - 18-5-2008 at 15:45

Where did you get that aspirator? I have been searching all over and I just can't seem to find anything worth buying, but your's looks pretty decent.

ADP - 18-5-2008 at 19:09

I purchased that one on eBay about 3 years ago, it's does really well for my expectations.

mr.pyro - 19-5-2008 at 19:38

excellent post ADP Ive been looking for something like this with pictures. approx what vaccum do you think your aspirator pulls?

ADP - 19-5-2008 at 20:21

Thanks, glad you like; I believe my aspirator pulls a vacuum down to at least 30mmHg, but it depends how hot or cold the water you run through it is IIRC. Colder water will produce a slightly stronger vacuum due to the vapor pressure of water. That interests me though... maybe one day this week I'll see how cold I can get water to boil...

It is very very useful for nitric since decomposition starts at 72dC which is normally much lower than it boils. I can get copious amounts via a considerably strong boil at 60dC, I remember it boiling at 40dC as well.

MagicJigPipe - 20-5-2008 at 09:51

ADP, in my experience, with density tests, the more liquid you use the better. I suppose because it "evens out" innacuracies. Where if the weight of the 1cc is off by even .05g, severly affecting accuracy, if the weight of 100cc is off by the same or even more the accuracy won't be as bad. As a preliminary test you could even use some cheap scale, determine the weight of the bottle and the volume of the liquid, and then... Well, I'm sure you know.

Try that. At least it will give you some idea until your decent scale arives.

Formatik - 20-5-2008 at 11:38

I can't get any good density readings with amounts like 1 mL, but I use at least 5 mL. With a graduated cylinder at 5 mL I've been able to get accurate density readings. Plus if you don't already do it, make sure you are at eye level with the meniscus (bottom) or a density reading will be useless and be off by magnitudes.

[Edited on 20-5-2008 by Schockwave]

ADP - 20-5-2008 at 15:42

Yeah MJP you're right, I ordered a 10mL Mohr pipet so I'll do that for sure, I might do 50mL or something and then divide by 50. I'll do the density tests this weekend. Today I did another vacuum distillation and got 170mL of nitric. I stored it separate because I used NaNO3 instead of NH4NO3 and I want to compare results with the density. After that I'll mix the two and get some ACS sulfuric to distill the two to get highest purity HNO3 for future endeavors...

mr.pyro - 21-5-2008 at 19:20

I tried a vac distillation today and ended up sucking out most of my vapors before they condensed. What did condense however was crystal clear and dissolved a penny very quickly. I am going to build a fume hood and gas trap and try it again soon. ADP did you notice any leaks around your ground glass or use any kind of sealant on the joints? Was there much nitric vapor sucked out of the apparatus by the vaccum?

ADP - 21-5-2008 at 21:46

Interesting you mention that problem - texaspete mentioned he had that problem as well, I personally put my receiving flask in an ice bath to prevent that but I've done without before and had no problems. I don't use any grease for my glass joints, i usually get a couple drops of dH2O and put on the outside of the joint once the vacuum is running to prevent any air from seeping it - it's usually negligible.

I think the best thing to make sure of is plenty of cold fresh water running through the condenser. I know the inside wall of my condenser 'rains' vapor and is pretty cool by the time it gets to the receiving end. What does your setup look like?

mr.pyro - 21-5-2008 at 22:30

I have all 19/22 glassware because I bought it as a kit. I hope to upgrade to 24/40 soon however.

My boiling flask is 500 ml and runs through a 200mm west condenser and into a 250ml receiver. I have an old robinair vacuum pump that pulls like 50 torr. I control the vacuum with a T joint and needle valve to let air in and keep it at a relative vacuum of about 20"Hg. I use an inline gauge to read it. Today I was getting nice rolling boiling with about 20"hg vacuum at around 65-70dC. I shall post pictures tomorrow or the next day as I have broken the setup down to head home for summer.

Also during the distillation I had constant ice water through the condenser and the receiving flask in an ice bath. I still noticed nitric vapor condensing in my tubing as well as my tubing connectors being attacked by the acid. However I can do ethanol distillations just fine without any condensation in the tubing.

[Edited on by mr.pyro]

mr.pyro - 26-5-2008 at 11:25

Here is my setup.

200g of nh4no3 was added to 300ml bullzeye drain cleaner sulfuric acid.

Temp did not rise past 30dC during addition.

here are the photos of my setup.

My valves getting attacked by acid condensing in the tubing.

About 50ml of acid came over after 45 min of distillation under a 20"hg vacuum. Acid mix was kept at 60C. Unfortunately I think my AN might have been wet or bad and it caused a poor reaction and it seemed to boil much less then other times I have done it. I am going to retry it with kno3 today that I know works.

I also tried the teflon vacuum grease mentioned in other threads. It worked very well except for on the receiving flask where I had to clean it off before I could pour out my product.

[Edited on by mr.pyro]

crazyboy - 26-5-2008 at 11:39

Don't fill the boiling flask more the halfway up!

and the thermometer bulb goes where the thermometer adapter meets with the condenser not in the liquid.

Also I would use an aspirator; nitric fumes could ruin your vacuum pump.

http://www.youtube.com/watch?v=3JlIPnyrZMw

^This may help.

EDIT: looks like ADP did it too the thermometer bulb doesn't go in the liquid it goes in the vapor!

[Edited on 26-5-2008 by crazyboy]

ADP - 26-5-2008 at 12:11

Quote:

Originally posted by crazyboy
looks like ADP did it too the thermometer bulb doesn't go in the liquid it goes in the vapor!

This is true for most distillations however, I am interested in keeping the temperature of the mix below 70dC therefore I am interested in monitoring that temperature not the vapor temperature as I would of MOST distillations.

mr.pyro - 26-5-2008 at 12:29

Quote:

Originally posted by ADP

Quote:

Originally posted by crazyboy
looks like ADP did it too the thermometer bulb doesn't go in the liquid it goes in the vapor!

As is the same reason that I have done it.

I really dont care about my vacuum pump that much. It is old and not very good. I also have a gas trap that should neutralize most vapors. Its just very annoying having NA condense in the tubes and attack my connectors.

[Edited on by mr.pyro]

ADP - 26-5-2008 at 13:23

The acid mist that does condense in my tube is no problem since I have an aspirator that just leads it into the sink. As for the tube it attacks the plastic but doesn't really have any effect so it's no big deal.

mr.pyro - 27-5-2008 at 13:12

Yesterday after completing one distillation I noticed a color change in my pumps oil.

Heres what came out of it.

Fortunately there was little rust inside of the actual pump mechanism and most of the rust came from the outer portion of the air inlet. I cleaned it up with some rust dissolver and gladly it looks brand new, just needs some new oil. Following, I will be buying an aspirator, but am reluctant to use it because I live in the middle of the desert and don't want to waste the water.

ADP - 27-5-2008 at 13:24

I understand your concern, I do believe that someone built a water "recirc" pump to reduce the waste of water

Hcl

nodrog19 - 2-6-2008 at 18:24

would hydrochloric acid work instead of sulfuric acid?
it is alot cheaper per mole of H+ where i live.
would Ca(NO3)2 work?

[Edited on 2-6-2008 by nodrog19]

ADP - 2-6-2008 at 18:28

Not for concentrations greater than about 31%...

not_important - 2-6-2008 at 19:17

Quote:

Originally posted by nodrog19
would hydrochloric acid work instead of sulfuric acid?
[Edited on 2-6-2008 by nodrog19]

Consider how aqua regia is made : 3HCl (aq) + HNO3 => NOCl + Cl2 + H2O

nodrog19 - 3-6-2008 at 15:59

oh. i found a recipe for NO2 from an old book so i will do that.
heat KNO3 and NaHSO4 and it gives NO or NO2.
would Ca(NO3)2 or NaNO3 work? i can only buy calcium nitrate and have no source for KCl. :mad:

ADP - 3-6-2008 at 17:12

Firstly, I hate to call you on this nodrog19 but what the hell are you trying to do? If you are trying a nitric acid synthesis, you DO NOT want NO2. A review of basic chemistry concepts would lead you in the right direction for nitric acid synthesis - H2SO4 + KNO3 --> HNO3 + KHSO4. You can use any nitrate, yes.

Perhaps you should read up on some chemical concepts before attempting to proceed with anything and always cross check something if you arent sure so you don't get hurt. NO2 is a highly poisonous gas that will kill you if you breathe too much...

Contrabasso - 4-6-2008 at 12:37

There are some very nice vac pumps using an aspirator and a water pump recirculating the water through the aspirator. Pumps such as boat bilge pumps or recreational vehicle tap water pumps have a reasonable pressure and flow, they tend to be 12 or 24 volts.

This way you can have a bucket of water and dump it when you change reaction, rather than paying for metered and scarce water.

Few vac pumps will stand conc acids!

Tsjerk - 4-6-2008 at 15:45

@ ADP
One way of making nitric acid is by bubbling NO2 into water. I believe some members here have done some experiments with that, I forgot the name of the method.

ADP - 4-6-2008 at 16:29

Yes I'm aware of that method:

2NO2 + H2O → HNO2 + HNO3

Not the best for future nitrations have you...

MagicJigPipe - 4-6-2008 at 19:51

I've done that many times before. I actually find it easier than distilling HNO3. Apparently, blowing air through the solution is a good way to oxidize HNO2 to HNO3.

ADP - 4-6-2008 at 20:00

Interesting, I've never heard of someone doing that practically? What is your method of producing NO2? Yes the nitrous acid that is formed reacts in the following way:

3HNO2 → HNO3 + 2NO + H2O

The resulting NO is oxidized to NO2 which continues to react with the H2O and the process is redundant...

In the end I suppose the excess dissolved NO2 can be removed by applying vacuum to the solution.

Tsjerk - 5-6-2008 at 08:10

Quote:

Originally posted by ADP
3HNO2 → HNO3 + 2NO + H2O

The resulting NO is oxidized to NO2 which continues to react with the H2O and the process is redundant...
.

I can imagine that the NO produced here will be blown out together with the air used to oxidize the HNO2, aswell as a large part of the dissolved NO2.

[Edited on by Tsjerk]

[Edited on by Tsjerk]

12AX7 - 5-6-2008 at 08:43

NO is oxidized to NO2 and both dissolve in solution leading to nitrous and hyponitrous acids which can also be oxidized.

Tim

Fleaker - 5-6-2008 at 15:00

There's always the hydrogen peroxide trick.

MagicJigPipe - 5-6-2008 at 16:33

Even the first time I did this "synthesis" I got almost all NO2. At least 75% of the distillate was DARK red gas. And I just bubbled it through water. It definitely works and still works to this day. I used 98% H2SO4 and dry KNO3.

More heat is required but it's damn easy. At one point, that's how I thought everyone did it.

ADP - 5-6-2008 at 19:58

Explain your method MJP. So you distill at a very high temp and allow lots of NO2 to come over then oxidize by blowing air through it? Interesting, what conc. HNO3 can you attain via this method?

497 - 6-6-2008 at 08:58

I too would be interested in hearing details about that. I wonder how it would work if you bubbled it into a solution of H2O2? Might help keep the losses of NO to a minimum.

nodrog19 - 17-6-2008 at 20:56

what about refluxing a mix of Ca(NO3)2 and H2SO4 in a boiling water bath?
the CaSO4 will precipitate. it only needs to be filtered, not distilled.
will 4Ca(NO3)2*NH4NO3*10H2O come apart in water (the Ca is less soluble)

12AX7 - 17-6-2008 at 21:42

Ca (and Ba) precipitation with sulfate works with many compounds. The problem is the fine precipitate that is difficult to filter...

Tim

497 - 21-6-2008 at 16:06

nodrog, a while ago I tried exactly what you said with the Ca(NO3)2 and believe me, it is extremely annoying to filter, it turns into a white mud.

Also, the solubility of CaSO4 is substantially enhanced by the presence of strong acids, so you will still have quite a bit of impurity left.

Klute - 21-6-2008 at 16:48

Adding H2O2 to conc. HNO3 is very dangerous! I really wouldn't consider it to oxidize any HNO2 in conc. HNO3...

I had one of the most frightening experience chemicallty-speaking when I added diluted pirahna solution to the acid recovery bottle, mainly constitued of depleted and diluted aqua regia.
I added not more than 20mL of pirahna diluted at least 5x with dH2O to the bottle, placed the cap (never screwing it on because of possible gas evolution), place dhte bottle at the rear of the fume hood, closed the hood, and went to the desk. 5 min after a phD student working in the same room came in a panic asking what reaction I was doing, I answered none, he told me something in my fume hood had exploded and was releasing irratating red fumes!

I rushe din to see acid litteraly pouring from the top of the hood, a great big red cloud (hopefully contained by the closed sash, but still very irrating), and the meatl bars dissolving visually... Once the fumes were mostly evacuated, i washed down the hood with a water hose very thoroughly, and then started taking evrything that was in there apart. All the metal bars were very damaged, aswell as most syringe needles, the things to attah bar together, etc etc.

even afetr washing with over 300L water with the hose, the drops that fell on my suit while washing up eat through it overnight!

And that was with fairly dilute solutions. Maybe the sulfuric acid sensitives HNO3 in a way or another, but never never mix aqua regia and pirahna together! Hopefully, I wasn't there when the bottle exploded, i would have suffered extreme wounds and burns, and hopefully the sash was completly down, a thing that a great deal of people at work don't do. This story is told to any new student or trainees at work to make sure they close the sash entirely when not working, and to keep it under your face at all times..

So I would discourage adding H2O2, whatever the concentration, to conc. HNO3. Maybe it has already been done by people without problems, but be warned!

hashashan - 5-7-2008 at 13:01

tried to distill some nitric acid under atmospheric pressure and bumped into some problems.
I followed the instruction in the books. Mixed 1:2 H2SO4 with KNO3 and started to distill that stuff in an all glass still.
All I got was nitric acid with 1.47 density which is not ever near to the 1.5 I was aiming at.
what could be the problem?

the other weired part was that after all the HNO3 got out of the goo in the flask, it melted into some bubbling liquid. any suggestions?

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