Sciencemadness Discussion Board - Diluting 90+% Nitric Acid to 70%?

Diluting 90+% Nitric Acid to 70%?

ManyInterests - 19-10-2021 at 17:53

I've been looking at various ways of preparing nitric acid, and from what I've seen it appears to be a lot easier to make fuming nitric acid than it is to make 65-70%. Largely because it has multiple steps you need to follow to get the more dilute kind.

So this got me thinking... is it possible to just dilute fuming HNO3 to 70% instead of making 65-70% from the start? I know it sounds like a dumb question. But I'd rather ask dumb questions than make dumb mistakes.

I do know it is a very exothermic reaction and I would need to do it slowly.

[Edited on 20-10-2021 by ManyInterests]

woelen - 20-10-2021 at 01:31

Just distill nitric acid from sulfuric acid and a nitrate salt, to which a little water is added beforehand. The water will distill over with the acid (azeotrope) and you'll get more dilute acid. Do not add too much water, it always is easier to dilute afterwards, than having to concentrate afterwards.

Tsjerk - 20-10-2021 at 11:51

Doing what woelen suggests is easier than making concentrated acid from the same salt and sulfuric acid. You will have a more liquid mixture in your flask with a lower temperature and less NO2. You can calculate how much water you would need for the azeotrope and take, let's say, 70% of that amount.

ManyInterests - 20-10-2021 at 12:35

I've seen people use water, dirty sulfuric acid (drain opener grade) and a nitrate salt. But I've also seen them use pure sulfuric acid. I have plenty of cleaned up sulfuric acid and would rather use that than my remaining drain opener grade.

So it's like cody's lab and nile red, but just less water added? That sounds simple enough. I'll need to make some and test its percentage. Looking at them making a distillation for hours then having to distill again and monitor very closely what comes out and having to replace the receiving container is a hassle. This is also a safety concern for me as I don't have a fume hood. I perform all these things in my balcony outside. No gasses get in while it's closed, but the way the ventillation works in my apartment is that the moment I open my balcony door they're going to enter my place like a vacuum which is a scary aspect when dealing with nitrogen dioxide.

Quote:

Doing what woelen suggests is easier than making concentrated acid from the same salt and sulfuric acid. You will have a more liquid mixture in your flask with a lower temperature and less NO2. You can calculate how much water you would need for the azeotrope and take, let's say, 70% of that amount.

I don't know the exact quantities, but I guess that is the spirit of experimentation.

So let's recap to see if I've understood it. Add the nitrate salt and chilled sulfuric acid (say 404 grams and 240 ml respectively), but instead of around 200 ml of water, I put in around 100 ml? I am using Nile Red's measurements. He used drain opener sulfuric acid which already has more water in it.

[Edited on 20-10-2021 by ManyInterests]

Sulaiman - 20-10-2021 at 19:15

There are many threads on the production of nitric acid here on SM,
I would use sodium or potassium nitrate with a little excess sulphuric acid to distill off RFNA at atmospheric pressure.
There are various methods used to eliminate the dissolved NO₂ (here on SM)
I can't think of a reaction where the dissolved NO₂ is a problem.

For dilute or concentrated nitric acid without distillation I would use a very slight excess of sulfuric acid with calcium nitrate,
the calcium sulfate produced has very low solubility and can be filtered off,
giving a filtrate with a little calcium sulfate and sulfuric acid contamination,
but mostly nitric acid.
Distillation of dilute nitric acid at atmospheric pressure gives a more concentrated acid,
(at less than azeotropic concentration)
but does not produce significant NO₂ contamination.

Dilution of nitric acid is exothermic,
but nowhere near as much heat is released compared to diluting sulfuric acid.
Chilling is good but not required.

ManyInterests - 20-10-2021 at 20:14

Thank you. I did look up some of the threads before I started this thread. But I think I got all the information I need for now. I hope to make my first batch of HNO3 next week. Right now it's all about getting the water pump properly connected to the water jacket. I have a tube that fits the pump, but is oversized for the water intake. I don't have any adapters, but if I glue the hose around the water intake it will still flow through the jacket just fine.

Quote:

For dilute or concentrated nitric acid without distillation I would use a very slight excess of sulfuric acid with calcium nitrate,
the calcium sulfate produced has very low solubility and can be filtered off,
giving a filtrate with a little calcium sulfate and sulfuric acid contamination,

That would be an interesting experiment, but I have no calcium nitrate to try it out. The only nitrate salt I have is potassium nitrate. Right now I decided to pull out my supply and grind it to a fine powder and I am putting it in the oven at around 70 Celsius to completely dry it out before returning to the container.

teodor - 21-10-2021 at 03:17

Storing 90%+ (e.g. 98%) nitric acid is not easy. I use a Duran Protect bottle with a red Teflon-lined cap but the acid ooze through the cap dissolving the protecting plastic from the outer side of the bottle. This is probably because night/day temperature changes and the ability of the acid to evaporate and condensate at the cap. So, I think it is not the best concentration to stock the acid.
I never had a problem storing 50% HNO3. But azeotrope concentration is already very peculiar and can decompose when the bottle is exposed to light, also it evaporates slowly even through the ground glass stopper.
So, if you don't need a concentrated acid (like in the case of just making nitrates and other general chemistry) I would recommend storing the main part as a 50-55% water solution.

But I am also interested to know how people store their highly concentrated HNO3. I know there are some special bottle but I never saw them close.

[Edited on 21-10-2021 by teodor]

Fantasma4500 - 21-10-2021 at 03:17

if you decide to go for distilling conc. HNO3 you can just DCM it, extract it like that.
then distill off the DCM at 40*C
should prevent nitric acid from decomposing, then dilute down accordingly
one person i spoke to made WFNA by Ba(NO3)2 and using some very small pore vacuum filtration glass cup which didnt allow the barium sulfate to pass through

Herr Haber - 21-10-2021 at 05:02

Quote: Originally posted by teodor

But I am also interested to know how people store their highly concentrated HNO3. I know there are some special bottle but I never saw them close.

[Edited on 21-10-2021 by teodor]

I use Duran bottles aswell but not the protected ones. I would be very annoyed to have one damaged by acid !

First, I'd remove the pouring ring. It only helps pressure escape and the gasses then attack the cap.
I ruined 1 cap with a pouring ring that still had a barb from molding then removed all pouring rings. No more problems.

I tried the other more expensive caps from Schott. They are better but not by much. They dont get attacked but they still leak enough vapours to discolor labels and such.
I havent felt the need to use the ones with an inner conical seal to store nitric acid.
They would probably be better but my conclusion was that it was simpler to make the acid when needed rather than store something like that for more than a couple of weeks.

[Edited on 21-10-2021 by Herr Haber]

Tsjerk - 21-10-2021 at 06:52

I tried DCM extraction of KNO3/sulfuric acid, it works and the product is colorless anhydrous HNO3, but it isn't very efficient. The salt slurry is very polar and is hard to extract with DCM. If your reagents are valuable to you, you could try to capture the DCM for repeated extraction.

ManyInterests - 21-10-2021 at 14:32

Quote: Originally posted by teodor

Storing 90%+ (e.g. 98%) nitric acid is not easy. I use a Duran Protect bottle with a red Teflon-lined cap but the acid ooze through the cap dissolving the protecting plastic from the outer side of the bottle. This is probably because night/day temperature changes and the ability of the acid to evaporate and condensate at the cap. So, I think it is not the best concentration to stock the acid.
I never had a problem storing 50% HNO3. But azeotrope concentration is already very peculiar and can decompose when the bottle is exposed to light, also it evaporates slowly even through the ground glass stopper.
So, if you don't need a concentrated acid (like in the case of just making nitrates and other general chemistry) I would recommend storing the main part as a 50-55% water solution.

But I am also interested to know how people store their highly concentrated HNO3. I know there are some special bottle but I never saw them close.

[Edited on 21-10-2021 by teodor]

I ordered several amber reagent bottles last summer. But none of them arrived. I realized I needed to improvise. I held onto a single empty bottle of triple sec. It has a completely plastic cap and is amber in color.

https://www.lcbo.com/content/dam/lcbo/products/088328.jpg/jc...

I also have another glass bottle with a plastic cap that I've wrapped completely in red electrical tape in order to stop any light from coming in.

I know it's really not good for long-term storage. But here's the thing. I don't plan on storing HNO3 of any concentration for any long period of time. Once I have some HNO3 that I need (either 68% or the 99%) I will use it as quickly as I can. Especially the WFNA. That stuff is deadly and seeing how it set nitrile gloves on fire so quickly makes me very afraid of keeping it for a while. I need it to make some energetics, and I will get my setup ready to make those the moment I obtain the nitric acid I need.

ManyInterests - 25-10-2021 at 07:59

I found this very fascinating thread that basically answers almost all my questions.

http://www.sciencemadness.org/talk/viewthread.php?tid=13090

The only difference between my setup is that I don't have a Clairsen adapter. But that shouldn't pose that much of a problem.

What I am concerned with is that he used pottery grade KNO3, while I am using homemade KNO3 extracted from Calcium ammonium nitrate cold packs. Also he uses drain opener H2SO4, while mine is cleaned up and probably a touch more pure. Does that mean I just need to add a little more distilled water to my flask?

SWIM - 29-10-2021 at 14:54

Good old Magpie.

He's a fine source. Really methodical and he would research everything first.

I think a few ml extra water would be a good idea if your acid is over 96%, but probably not critical.

If you add too much there will be some lower strength tailings at the end of the distillation, but foaming won't be as much of a problem and yield will still be pretty good unless you really overdo it.

edit: Its probably not a matter of how clean the acid is, but how strong. The dark impurities in industrial grade acid don't seem to have much of an inhibitory effect on the reaction.

[Edited on 29-10-2021 by SWIM]

ManyInterests - 1-11-2021 at 15:56

OK so I just want to give my report and documentation of my first attempt at making Nitric acid.

Firstly I am proud to say that my safety setup was top notch. Exactly no gasses made could have harmed anyone. They were fully contained.

Since safety is all good... my result wasn't. I did not need a clairsen adapter because I was using a 1000ml double necked boiling flask. I used Magpie's recommended quantities and the foaming + resultant salt cake never got close to leaving my flask. The problem is that breaking up the salt cake was a major pain and I needed a lot of water and sodium carbonate in order to dissolve it and neutralize any bisulfates before I poured the remains down the drain.

The problem was that my nitric acid is really, really weak. Using this chart I probably got a concentration of 19.5 to 21% at the most.

https://www.handymath.com/cgi-bin/nitrictble2.cgi?submit=Ent...

I am really not sure what happened. But as I saw that the flask was going to dry up. What I did was lift the flask out of the heating mantle to prevent any cracking, I think I might have accidentally poured the water that was condensing in my allihn condenser. That might have been the biggest problem.

I will make my first attempt at fractional distillation to see if I can get my weak solution up to 68-70%. But in all honesty I would like if I just got my desired strength the first time around... easier that way. Or make it stronger than necessary and just dilute it, which is what I was originally asking about.

Oxy - 1-11-2021 at 19:11

Quote: Originally posted by Antiswat

if you decide to go for distilling conc. HNO3 you can just DCM it, extract it like that.
then distill off the DCM at 40*C
should prevent nitric acid from decomposing, then dilute down accordingly
one person i spoke to made WFNA by Ba(NO3)2 and using some very small pore vacuum filtration glass cup which didnt allow the barium sulfate to pass through

According to MSDS (https://www.carlroth.com/medias/SDB-8424-IE-EN.pdf?context=b...) HNO3/DCM is potentially explosive mixture. IIRC someone on the forum also warned about it, I don't remember if he actually experienced the explosion.

ManyInterests - 1-11-2021 at 21:10

Quote:

Well I have no DCM and I won't be using it if there is any explosion hazard (which is also why I will not be making azeotropic hydrazine for my NHN. I refuse to take any chances. I will freebase my hydrazine sulfate with sodium hydroxide and ethanol and use the solution I get from there for that purpose).

I wanted to give another updated on my fractional distillation. It was my first ever fractional and I am mildly confused if I was doing this right.

So what I got pretty much all the time was water with a slight nitric acid touch. I decided not to keep them and neutralize them instead. What was left in my boiling flask after almost an hour of that was a much stronger nitric acid than I had previously, but it was around 40%. I know it's blasphemy to do this, but I also neutralized it since I did want to try to purify it further later. What was left was too little anyway.

It was my first fractional distillation and my first distillation ever. Pretty exciting! But for the next time, I'll follow Magpie's instructions again, except I will use 10ml more sulfuric acid (I am confident I have at least 96%) and use far less water. Like around 10ml. So 110ml of acid to 10ml of water. The acid isn't the problem. Getting sulfuric acid is easy where I live and I have plenty of concentrated hydrogen peroxide to purify it. But the nitrate salt is a pain and much more expensive for me to get.

ManyInterests - 3-11-2021 at 15:03

My god I feel so embarassed... also NileRed lied to me! Now I know exactly why my previous nitric acid synthesis went awry.

What happened is actually as simple as it is stupid. At the end of my original synthesis I had 100 ml of product in my flask but as I tried to raise my flask from the mantle I heard an audible 'glug glug glug'. I then noticed that my 100ml was now around 250ml of something. I wasn't sure what happened. I thought there was some water stuck in the alihn consender, but that made no sense.

Something like this happened again, and I know exactly what happened... The sodium hydroxide trap I setup (like in NileRed's video) actually sucked the hydroxide solution into my flask of nitric acid. It's actually amazing I had any left at all. Or if there was any left.

Next time I will do what Magpie showed and just have a tube. Or not even. My fan will take care of the fumes. God I feel stupid. 450 grams and 200ml of KNO3 and H2SO4 lost for nothing.

ManyInterests - 3-11-2021 at 22:43

Well that solved a major problem. Following Magpie's instructions. I only added 20ml of water instead of his 48ml. Final yield is less than 100ml of acid, at around a concentration of 59 or 60%. I'll do a fractional distillation and hopefully get it to 68 or 70%.

Next time I try it I'll add less water. That should do the trick.

Tsjerk - 4-11-2021 at 01:06

Quote: Originally posted by ManyInterests

Something like this happened again, and I know exactly what happened... The sodium hydroxide trap I setup (like in NileRed's video) actually sucked the hydroxide solution into my flask of nitric acid.

What video?

ManyInterests - 4-11-2021 at 14:01

Quote: Originally posted by Tsjerk

Quote: Originally posted by ManyInterests

What video?

This one: https://youtu.be/KBeo8nww21g

Now his funnel was floating atop the sodium hydroxide solution while mine was at the bottom. The first time I did it I put 250ml of sodium hydroxide solution in a 1000ml beaker. It still sucked up a lot of the solution at some moment. I am not sure why.

I decided to omit the trap all together, like what Magpie did in his article and doug's lab did in his video on making nitric acid.

I think my reduced yield had something to do with me omitting to grease the joints, which caused some acid gas to leak out. Another problem is while cleaning my joint, I accidentally snapped part of the dripper (I don't know what that part is called. But it looks like the lower part of a glass funnel). It still drips the acid into my flask just fine, but I am sure something is not working as optimally as previously.

ManyInterests - 7-11-2021 at 19:13

My attempts to concentrate my dilute batch either went almost right or did nothing. I was just one gram away from the correct concentration... and it was a much higher heat.

I had a concentration of 1.3595 using that chart (27.19 grams to 20ml). Next time I will add a 10ml excess of sulfuric acid (just in case it isn't strong enough) and only 5ml of water. I want this attempt to succeed. Better to dilute than to concentrate, which I am clearly having problems with.

[Edited on 8-11-2021 by ManyInterests]

Oxy - 7-11-2021 at 21:14

Quote: Originally posted by ManyInterests

Be careful with that. Wrong setup of the trap and suck back may lead to explosion, serious injury, damage, poisoning or even death.

ManyInterests - 7-11-2021 at 22:29

Quote: Originally posted by Oxy

Quote: Originally posted by ManyInterests

Be careful with that. Wrong setup of the trap and suck back may lead to explosion, serious injury, damage, poisoning or even death.

Yes! I am extremely lucky that the only thing that happened is that my final product was ruined and nothing else. I am not using a hydroxide trap anymore.

I've decided to only make my distillations at night since I don't want any sunlight damaging my nitric acid. Also one thing I am noticing that no matter how little water I add. I am always getting a far too dilute solution. I haven't done my latest attempt with 105/110ml of sulfuric acid + 5 or 6ml of water yet, but I am thinking about what else may have gone wrong.

I know that when making fuming nitric acid, your temperature must not go above 85 or 90 degrees Celsius. But what about lower concentrations? I've seen the videos and even Magpie's article doesn't mention a number on the temperature.

I saw in Doug's lab that the temperature went up to 116 or 120 degrees Celsius, so that's what I turned my mantle up to. Is this excessive for the azeotrope? Or do I just set the temperature to 85 like for fuming?

Also do I need to cover my glass in aluminum foil if I am making it during the night with no sunlight (I do use my flashlight to illuminate it, otherwise it's too dark to see what's happening) or is that not necessary? Is it any light that causes degradation or is the UV rays from sunlight?

And I kinda feel dumb to ask this again. But is it possible WFNA down to 70% or will that cause problems? All I got was that it would be an exothermic reaction, which I understand, but will the addition of water not work exactly or what?

woelen - 8-11-2021 at 00:01

No need to do the distillation in darkness. Full bright sunlight may cause some decomposition, but I think that heating the acid causes much more decomposition than the sunlight. If you do the synthesis at the right time, you could do it somewhere in the shadow of a tree or building just to avoid direct sunlight.

ManyInterests - 8-11-2021 at 08:07

Quote: Originally posted by woelen

No need to do the distillation in darkness. Full bright sunlight may cause some decomposition, but I think that heating the acid causes much more decomposition than the sunlight. If you do the synthesis at the right time, you could do it somewhere in the shadow of a tree or building just to avoid direct sunlight.

Thanks for the advice on the sunlight. I guess one of the other reasons why my concentration was so low (albeit I got so close last time) was due to the high heat. What is the better heat level for this? would putting it at 85 degrees Celsius work as well to make RFNA or 68% as it does for WFNA?

Oxy - 8-11-2021 at 08:24

Quote: Originally posted by ManyInterests

Yes! I am extremely lucky that the only thing that happened is that my final product was ruined and nothing else. I am not using a hydroxide trap anymore.

Why not? Traps are good if they are setup in a correct manner. Just test it before running a reaction.

Quote: Originally posted by ManyInterests

I've decided to only make my distillations at night since I don't want any sunlight damaging my nitric acid.

Have you ever heard of aluminium foil or towels?

ManyInterests - 8-11-2021 at 08:47

Quote:

Why not? Traps are good if they are setup in a correct manner. Just test it before running a reaction.

When I start using them. The trap doesn't immediately start sucking up. I don't know when it would do that, I will try a different setup in order to not have the funnel completely submerged in the solution. That should prevent any accidental suck up.

Quote:

Have you ever heard of aluminium foil or towels?

I've mentioned it before, I did use them. However I would like to observe what is happening.

Edit: I would really like some advice on the temperature with some solid numbers. I've wasted a lot of my precious KNO3 already.

[Edited on 8-11-2021 by ManyInterests]

Oxy - 8-11-2021 at 09:40

Yes, the whole idea is to submerge the hose output/funnel/whatever in a way that if there will be pressure change and reactor will start to suck then the process will simply break.
The level of liquid in trap should be of course continuously watched as the volume may increase due to dissolving something or temperature change. So, even if the trap will look good when starting then after some time it might need some adjustment.

Regarding temperature - the thing you ask is the influence of the temperature on decomposition rate of HNO3. I am not 100% sure but I would say that water presence will probably not change anything. Keep temperature as low as possible with reasonably fast distillation rate. There are always some losses but you would need to produce a lot of NO2 to see the effect. In temp of 90 deg C and 1 atmosphere pressure 1 mol of NO2 takes almost 30 liters of volume. You would need to produce it a lot to see a drastic effect.
Optionally you could submerge your receiver flask in ice cold water (the colder the better and try to condense NO2). But it will not produce clean HNO3

ManyInterests - 8-11-2021 at 14:09

Quote:

Regarding temperature - the thing you ask is the influence of the temperature on decomposition rate of HNO3. I am not 100% sure but I would say that water presence will probably not change anything. Keep temperature as low as possible with reasonably fast distillation rate. There are always some losses but you would need to produce a lot of NO2 to see the effect. In temp of 90 deg C and 1 atmosphere pressure 1 mol of NO2 takes almost 30 liters of volume. You would need to produce it a lot to see a drastic effect.
Optionally you could submerge your receiver flask in ice cold water (the colder the better and try to condense NO2). But it will not produce clean HNO3

Yes. That was my main question. Every video and synthesis description for WFNA or RFNA always stated the number for the temperature, while instructions for the 68% were always fairly vague like 'turn it to high' or what Magpie wrote at '70% of max power' If I did what Magpie wrote, it would meaning having to set my mantle to 210 degrees, which is too high. My mantle can go higher than the 300 degree max (I boiled sulfuric acid multiple times).

I do need to experiment with my mantel's heat settings. This is because I cannot stick my mantel's thermometer into the distillation joints. I have a feeling that it is dependent on the reading it gets from the thermometer to know when to stop heating up, otherwise it just keeps on heating up. I need to make sure that is not the case, otherwise I will end up ruining my end product again. I came so close at my 3rd attempt. 4th one I hope to make RFNA and dilute it down to 70%. I only need a little WFNA.

I do use an icebath. The NO2 can be cleaned out by bubbling, or doing what Darian Ballard did, by putting the flask in a bowl of sodium carbonate, putting the whole thing in a freezer bag, and putting it in the freezer for a bit (with the cap not being too tight) which will result in it clearing up.

Edit: I was right. My mantel will continue heating without any input from it's thermometer. No wonder my yields were so low. Even if I didn't have the hydroxide mishap. The heat would have obliterated much of my precious nitric acid. Thankfully I managed to find a way to fit it into distillation joint. I hope this will work correctly now.

[Edited on 8-11-2021 by ManyInterests]

[Edited on 8-11-2021 by ManyInterests]

[Edited on 8-11-2021 by ManyInterests]

ManyInterests - 9-11-2021 at 01:00

OK this is funny. I don't understand what happened. But it's really weird.

So given the irregularities of the heating. What I did was set my mantel temperature to around 65 to 70 degrees, but the solution did boil and my thermometer did fluctuate from 85 to 116 degrees and I did get dripping in my receiver flask.

Problem is. The process never took more than an hour or two before it clearly starts to dry up and start to form a hard potassium sulfate cake. This time there was no such drying. In fact for the past 4 hours (I must have run it for 7 hours or 8 hours at least) there was no drop in how much solution was in my boiling flask. I raised the temperature but it did not appear to have any discernible effect. I wrapped everything in foil and I will look at what I got tomorrow.

ManyInterests - 9-11-2021 at 08:06

OK I finally did it. Got a density of 1.446. The yield was small, but it is a success. I have some RFNA! Just need to dilute it down to 70% VERY carefully at room temperature and I can finally go ahead with my experiments!

I turned out that what was left boiling in my flask was just the sulfate. Turning it off caused it to dry rather quickly. At any rate it looks fairly soft and not hard. So cleaning it should not be a problem.

Feels good man! I feel like I went through another great hurdle!

ManyInterests - 19-11-2021 at 21:38

Just putting it that I appear to have gotten a handle on making nitric acid. Today I made two batches. Both appear to be around 70%. One of them have NO2 contamination while the other is nearly colorless.

My solution was, using magpie's formula, was to add 8 to 9 ml of water (and not more) with very dry powdered KNO3 and a few drops more sulfuric acid than what he put in. That appears to be doing the trick just fine.

I had to turn my mantel on and off multiple times as I couldn't put my thermometer in it and I needed some way of controlling the temp. either way it didn't take hours upon hours but was done in less than hour. I hope I can get similar results with the attempts for WFNA.

ManyInterests - 26-6-2022 at 10:33

I came back to this thread because while I have already made plenty of good nitric acid (fuming and 70%). But I have one question.

when working with different nitrate salts. Like with NileRed in his video on making nitric acid, he notes that you could use 404 grams of potassium nitrate or 320 grams of ammonium nitrate.

And going back to Magpie's thread on making nitric acid, he used 225 grams of potassium nitrate. If I was using sodium nitrate, how much should I use? This is because I will be making a good amount of sodium nitrate and I also want to use that to make nitric acid.

Rainwater - 26-6-2022 at 15:23

You should readup on on it
Chapter 4
Stoichiometry of Chemical Reactions .
https://openstax.org/details/books/chemistry-2e

The quantities you stated are likely to be molar equivalents. I didn't run the numbers so lets do that now.

So KNO3 has a molar mass of about 101g/mol
And NH4NO3's molar mass is about 80 g/mol

404 ÷ 101 = 4 mol
320 ÷ 80 = 4 mol
So if you have 4 mols of a nitrate salt, you need 4 mols of H2SO4 to react with it.

H2SO4 has a molar mass around 98 g/mol
98*4 = ~400 ish if your acid is 100% pure

There is a section explaining the math to calculate the amount required when purity is known.
Edit. I cant find the reference
Basicly
X = Weight needed (pure)
Y = purity of your compound ( 100% = 1.00 3% = .03)
Z = weight if your compound equivalent to pure substance

Z = X × ( 1 ÷ Y )
Say you needed 1g of pure acid. And all you have is a 50% solution.
1 × (1 ÷ .50) = 2g of solution will be needed

So to answer your question, you need to know the molar mass of sodium nitrate. Then know how much product you wish to generate.
That will tell you how much acid to add.

[Edited on 27-6-2022 by Rainwater]

ManyInterests - 26-6-2022 at 16:07

OK, so I will need to find the molar mass of sodium nitrate to do it then. I did see in a book that 58 grams of sodium nitrate was equal to 68 grams of potassium. If that is the case I can work with that. But obviously I will need more information.

I am confident about the purity of my stuff. It isn't obviously as pure as store bought stuff, but I am confident I can make all sorts of nitric acids with them. From fuming to 70%.

edit: I believe this site will help:

https://www.convertunits.com/molarmass/Sodium+Nitrate

https://www.convertunits.com/molarmass/Potassium+Nitrate

https://www.convertunits.com/molarmass/ammonium+Nitrate

This should tell me all I need to know. Goodie!

[Edited on 27-6-2022 by ManyInterests]

B(a)P - 26-6-2022 at 17:17

Quote: Originally posted by ManyInterests

OK, so I will need to find the molar mass of sodium nitrate to do it then. I did see in a book that 58 grams of sodium nitrate was equal to 68 grams of potassium. If that is the case I can work with that. But obviously I will need more information.

I am confident about the purity of my stuff. It isn't obviously as pure as store bought stuff, but I am confident I can make all sorts of nitric acids with them. From fuming to 70%.

edit: I believe this site will help:

https://www.convertunits.com/molarmass/Sodium+Nitrate

https://www.convertunits.com/molarmass/Potassium+Nitrate

https://www.convertunits.com/molarmass/ammonium+Nitrate

This should tell me all I need to know. Goodie!

[Edited on 27-6-2022 by ManyInterests]

You can just read it off a periodic table or even easier go to the SM wiki and get the molar mass from the write up of the compound you are interested in. It might be a good idea to work it out from a periodic table a few times though, this will help you understand what molar mass is all about. It is a very important foundational knowledge for chemistry. This explains it well.

https://youtu.be/PAqzpZ-nMlg

Fantasma4500 - 27-6-2022 at 05:07

https://www.webqc.org/balance.php?

this is very helpful and can even give you molar masses if you are a bit creative and the damn thing wont acknowledge the reality of what youre trying to accomplish, for instance KNO3 = KNO2 + O2 will give you molar mass of all 3

ManyInterests - 4-8-2022 at 12:59

Just putting in a report (public lab note). I tried to go for WFNA again but ended up with a product that has a specific gravity of 1.486233 at 15C. (114.44 grams to 77ml) This would bring it to around 88.5% nitric acid (10 percentage points below where it needs to be). I used 185 grams of sodium nitrate (dried in the oven overnight) to 120ml of cleaned and purified sulfuric acid (close to 98%) and no added water whatsoever. I did this in a 2 liter boiling flask to give myself more room.

Is it possible that the size of the flask is what caused it to be less concentrated? Because I did see stuff dripping back into the flask as it was trying to get up to the joints and go over. I used chilled water to go through the jacket to allow for appropriate cooling and placed the receiving flask in a salt-water ice bath.

Next time I will use a smaller boiling with similar proportions. Either way I need to look up on how to dry nitric acid, I think that'll be an easier solution. At least there is some good news... I have no problem making good clean nitric acid. Just not the concentration I want.

It is strange. Because the first ever time I went for fuming nitric acid it worked perfectly. I got nearly 100% the first time. I don't know what is going wrong.

edit: I am not sure if the size of the boiling flask was responsible. But I will try a smaller one anyway. I see that the sulfate cake still looks moist. It is also possible that my sulfuric acid might need a little more boiling before use? Either way, before I try again, I want to try to dry it more.

[Edited on 4-8-2022 by ManyInterests]

Tsjerk - 4-8-2022 at 13:19

How did you determine the concentration of the sulfuric acid?

CharlieA - 4-8-2022 at 14:56

"Just putting in a report (public lab note). I tried to go for WFNA again but ended up with a product that has a specific gravity of 1.486233 at 15C. (114.44 grams to 77ml)"

I don't mean to be picky, but 114.44/77 = 11.5; only 2, not 7, significant figures. To increase your precision, the easiest way would be to measure the volume more precisely, perhaps with a graduated pipette or burette.

ManyInterests - 5-8-2022 at 13:47

Quote: Originally posted by CharlieA

"Just putting in a report (public lab note). I tried to go for WFNA again but ended up with a product that has a specific gravity of 1.486233 at 15C. (114.44 grams to 77ml)"

I don't mean to be picky, but 114.44/77 = 11.5; only 2, not 7, significant figures. To increase your precision, the easiest way would be to measure the volume more precisely, perhaps with a graduated pipette or burette.

I got a glass graduated pipette. i never thought to calculate it that way. I use a graduated cylinder for my calculations. I think I will try again then.

CharlieA - 5-8-2022 at 14:14

Quote: Originally posted by ManyInterests

Quote: Originally posted by CharlieA

I got a glass graduated pipette. i never thought to calculate it that way. I use a graduated cylinder for my calculations. I think I will try again then.

CORRECTION: 114.44/77=1.5 (2 significant figues)

I am glad to hear that you have a graduated pipette. If it is graduated in 0.1 ml increments, then you can estimate a volume to 0.01 ml; for a sample size greater than 10 ml this will allow you to measure the volume to 4 significant figures. With the sample size mass that you used above indicating 5 significant digits, then your calculation will be good to 4 significant figures, or 1.xxx g/ml.

Of course, your estimate of accuracy must take into account the accuracy of your measuring instruments, not just the precision. All in all, I think that you are heading to achieve good precision in your measurements.

Tsjerk - 6-8-2022 at 00:41

Sure 114.44/77 = 1.5, but assuming the graduated cylinder has a better than 1% precision and assuming the liquid was exactly on the 77 ml mark you could say the volume was in the 76.5 - 77.5 range. That would mean a density between 1.48 and 1.50, which would be 89 - 98% at 20^oC.

A density of 1.5 would be something like 80-100%. But either way, a better precision would be nice. If there is a lot of water in there, there is only one reasonable source which would be the sulfuric acid. The sulfuric acid you could titrate.

Sir_Gawain - 16-10-2022 at 19:58

I've done it. I made a batch of nitric acid using ammonium nitrate and the concentration was around 85%. Then I diluted it to 68% with distilled water. The reaction wasn't very exothermic, but the diluted acid retained a yellow color. I then distilled it again (not fractional) and checked the concentration.

With ammonium nitrate I haven't been able to get it over 85%. Using the same sulfuric acid, and potassium nitrate, 98% was obtained. I guess for dilution though, a lower concentration is good because it won't be so exothermic.

ManyInterests - 22-5-2023 at 18:52

OK, so I got something to ask since I got some nifty new equipment.

So previously when distilling, I could not control for temperature because I could not put in the thermoprobe into my flask when distilling, so I had to device a very peculiar 'on-off' dance where I would observe how the reaction is going in the flask and once I feel it is getting too hot (and the foam is rising up to the joints... not good!) I would turn it off and let it cool down a little before turning it back on again once it cools off a little.

This system worked. It isn't super efficient or scientific, but it worked. But now I have a knew glass thermometer adapter that can accommodate my thermoprobe easily, so I can have more control over the temperature.

When using it, my thermometer can go half-way into my 1 liter flask, and around a quarter in to my 2 liter flask. Would this pose a problem? I also need some confirmation as to what temperature range I should be looking for when making WFNA. Is it around 85 to 90C?

I did learn that... yes, diluting the acid down is not an issue and it can be done quite easily, just control for the exothermic reaction and it isn't going to be an issue.

Right now I just want to make sure I am going to get good WFNA consistently. I also wanting to explore how the temperature control can be used to further purify nitric to WFNA by distilling it a 2nd time with sulfuric acid and keeping the temperature range only at 85 to 90C?

Rainwater - 23-5-2023 at 01:34

Using an excess of sulfuric acid will help remove any water in the appratus.
I did not see that mentioned before

Using an insulated fractional column of some kind, place the thermowell just above your solution, set your temperature to 86c (if i remimber correctly) and compare the head temp.
Anhydrous acid will come over first, when the lower thermowell reads a different temperature than the head, your starting to get water in your acid.

NO₂ contamination can be removed with a gentle vacuum and reflux of you want a nice clear acid. But if your diluting later, their isnt much point as the addition of water will clear up the acid aswell.

Alkoholvergiftung - 23-5-2023 at 05:08

I wouldnt destill ammoniumnitrate. I ve read that they used ammoniumsulfate to purificate Sulfuric acid the ammoniumsulfate reactes with HNO3 to form N2O gas. I think the same oculd happen when you destill ammoniumnitrate. (Ive read it again it only happens when you have an exceed of H2SO4.)

[Edited on 23-5-2023 by Alkoholvergiftung]

Lionel Spanner - 23-5-2023 at 13:35

For what it's worth, I've successfully distilled azeotropic nitric acid using concentrated sulphuric acid with hydrated magnesium nitrate (fertiliser grade). The mixture stops evolving nitrogen dioxide and the azeotrope comes over as a clear pale yellow liquid.

ManyInterests - 23-5-2023 at 18:49

Quote: Originally posted by Rainwater

Using an excess of sulfuric acid will help remove any water in the appratus.
I did not see that mentioned before

Using an insulated fractional column of some kind, place the thermowell just above your solution, set your temperature to 86c (if i remimber correctly) and compare the head temp.
Anhydrous acid will come over first, when the lower thermowell reads a different temperature than the head, your starting to get water in your acid.

NO₂ contamination can be removed with a gentle vacuum and reflux of you want a nice clear acid. But if your diluting later, their isnt much point as the addition of water will clear up the acid aswell.

That would work if I had a 2 necked flask, but I don't. I only have a 1 neck. I wish I could put in two thermometers to get one reading at the bottom and the other at the top. Unless I am misunderstanding you?

I am OK with a little discoloration. I do, however, wants to consistently get WFNA to use for some RDX synths. For everything else I can dilute it down or just make it an azeotrope from the get-go since from what I've seen, the only thing that really needs pure WFNA is RDX. Most everything else from nitroglycerin or EGDN and other stuff can be done with a simple azeotrope, which hasn't been a problem for me for a long time.

Raid - 24-5-2023 at 06:31

you could use dilution calculation to dilute the HNO3

chornedsnorkack - 24-5-2023 at 09:42

Quote: Originally posted by Raid

you could use dilution calculation to dilute the HNO3

Not this one. Volume is not conserved on mixing!

ManyInterests - 30-5-2023 at 21:11

This is my current setup for making nitric acid. I don't see that much nitric acid coming over as compared to the previous times. How long does it normally take under these circumstances? I hope it isn't too big or letting it come back down or anything...

IMG_20230531_010725162_HDR - Copy.jpg - 1.6MB

B(a)P - 30-5-2023 at 22:03

It depends how cold the surrounding environment is and how strong your heating.
Going slower will lead to less nitrogen dioxide contamination.
When I have done this previously it takes around 15 minutes for the first few drops to come over. At 30 minutes the nitrogen dioxide will have stopped and I would switch out the receiver, only required if you want WFNA.
The only real concern with regard to distillation rate is the amount of time you have available to supervise the reaction. If you are running short of time you can consider insulating up to the condenser.

Edit, some questions for clarity
How long has it taken for anything to come over?
How many drips are you currently getting per minute?

[Edited on 31-5-2023 by B(a)P]

ManyInterests - 30-5-2023 at 22:26

Quote: Originally posted by B(a)P

It depends how cold the surrounding environment is and how strong your heating.
Going slower will lead to less nitrogen dioxide contamination.
When I have done this previously it takes around 15 minutes for the first few drops to come over. At 30 minutes the nitrogen dioxide will have stopped and I would switch out the receiver, only required if you want WFNA.
The only real concern with regard to distillation rate is the amount of time you have available to supervise the reaction. If you are running short of time you can consider insulating up to the condenser.

Edit, some questions for clarity
How long has it taken for anything to come over?
How many drips are you currently getting per minute?

[Edited on 31-5-2023 by B(a)P]

Yeah, insulation is a must, I haven't gotten much of it. It's been hours and I am kinda tired. I will need to cut this one short for now.

For the questions is I did see some drips at first, but they ceased kinda quickly. For the 2nd question, I don't think I saw anything really drip over.

The temperature has been very stable at 90C. No changed or fluctuations.

I agree that insulation is needed. What I am going to do is power off my mantle and just leave it there for the night. I'm too tired to dismantle it and the last thing I want to do is make a mistake due to fatigue.

I set it up that I can unplug the mantle while leaving the water pump going.

I will try to restart again tomorrow, with the same stuff already in the flask, this time not being super iffy with the temp control. When I do again with fresh reagents I will absolutely wrap everything up in aluminum foil except for the receiving flask and joint so I can see if anything is coming over.

Nitric acid has been an adventure and this is going to be an even nicer one. I hope I don't get any acid on my self by accident and I hope that by the end of it I will be able to consistently make WFNA from the get-go without additional distillation.

I will post again tomorrow once I have more to report.

Rainwater - 31-5-2023 at 01:24

The temperature probe is not located at the very top of the distillation head, could be the problem.

ManyInterests - 31-5-2023 at 06:44

Given the fact that I got a big fat nothing I am inclined to agree. I had a mishap with the water adapter. The hose somehow got loose from the bucket sometime overnight. But that didn't do any damage. All the water has long evaporated (and my balcony is a bit cleaner).

Cleaned all the apparatus and next time (tonight) will restart the whole thing with the adapter higher up. The thermoprobe is a tiny little one and I kept it at the bottom. If moving it up will help I will do that.

I also will need to look for another adapter. Using this setup requires the acid to climb too much. I had another simpler 3-way adapter, but one of the joints was not what I thought it was. I need to find another that will fit into the condenser so I can give the acid a shorter path to distillation.

I also kept the water in the water pump bucket VERY cold. Is this appropriate?

Sir_Gawain - 31-5-2023 at 07:04

Generally, colder is better. It decomposes less at lower temperatures. I once got it so cold I condensed some nitrogen oxides into a bluish liquid.

Rainwater - 31-5-2023 at 07:55

Nitric acid is not something you want to leave unattended. From personal experience
I was distilling some water (big woop) and left it overnight, what could go wrong.
about 3-4am my smoke alarm is going off, i run down stairs, and see my heating mantle is black, a 1L rbf is melted and cracked.

Turns out, when my boiling flask was empty, the head tempature dropped, so the mantle cranked up the heat. As their was no more water to distille, the temperature continued to drop and the mantle got hot enough to melt borosilicate glass.
At those tempatures the byproduct KHSO₄ will decompose into K₂S₂O₇ which is a strong oxidizer

Now i use a sand bath set to a safe tempature for di water.K2S2O7

Second mishap, the tempature probe fell out. Sand melts aswell.

ManyInterests - 31-5-2023 at 12:14

Quote: Originally posted by Rainwater

Nitric acid is not something you want to leave unattended. From personal experience
I was distilling some water (big woop) and left it overnight, what could go wrong.
about 3-4am my smoke alarm is going off, i run down stairs, and see my heating mantle is black, a 1L rbf is melted and cracked.

Turns out, when my boiling flask was empty, the head tempature dropped, so the mantle cranked up the heat. As their was no more water to distille, the temperature continued to drop and the mantle got hot enough to melt borosilicate glass.
At those tempatures the byproduct KHSO₄ will decompose into K₂S₂O₇ which is a strong oxidizer

Now i use a sand bath set to a safe tempature for di water.K2S2O7

Second mishap, the tempature probe fell out. Sand melts aswell.

This is why I turned the mantle off. I just left the water pump on. It did have an accident, but not a big one.

Rainwater - 31-5-2023 at 14:13

If your unable to get the tempature probe into the distillation head, then a sand bath will work. Its much slower but if you distilled to dryness it ensures your equipment will remain at a non destructive tempature.
Setting it to something around 200c at the start will warm things up and k8ckoff your reaction
Then when distillate starts comming over, then turning it down to whatever tempature it currently reports.
It defeats the purpose of having a PID controlled mantle but at the same time allows experimentation while the proper glassware is obtained

ManyInterests - 31-5-2023 at 20:14

Quote: Originally posted by Rainwater

If your unable to get the tempature probe into the distillation head, then a sand bath will work. Its much slower but if you distilled to dryness it ensures your equipment will remain at a non destructive tempature.
Setting it to something around 200c at the start will warm things up and k8ckoff your reaction
Then when distillate starts comming over, then turning it down to whatever tempature it currently reports.
It defeats the purpose of having a PID controlled mantle but at the same time allows experimentation while the proper glassware is obtained

I think I might have gotten a handle on this. I have restarted the distillation with the old stuff. I managed to get a small probe (wrapped securely in teflon tape to protect it) and placed it at the top of the joint. You can see it in the picture. It's the white thing at the top.

I hope this works. I will observe it closely.

IMG_20230601_000549950_HDR - Copy.jpg - 1.9MB

ManyInterests - 31-5-2023 at 20:27

Ok quick update. This is mostly a dud. I do see some nitric acid, but they are stuck in the alihn columns... I will still give it a bit more at the 93C that I set, but otherwise I will need to wait for the flask to cool down until I can recover the acid and get a fresh flask full of sodium nitrate and try again.

I was using some freshly made potassium nitrate, which I probably try again. I have some questions regarding the purity of the stuff, but it should still work for making nitric acid. I do see some... they're in the column, I need to tilt it more next time.

edit: Some mild dripping! progress!

edit2: So it is still mostly a dud even though I did get something out of it. This probably had a lot to do with the events of last night. But at least I know I am getting something now, so attempts 2 and 3 should yield better results.

edit3: lots more coming over, but it is at a higher temp than 100C. I fear it might not be WFNA. But I can redistill. I hope.

edit4: OK I am superbly confident this is the azeotrope. the temperature it is coming at is 110 or 113C or so. At least I know it isn't a dud!

Should I lower my probe more to get a better reading and distill over WFNA instead of the azeotope?

[Edited on 1-6-2023 by ManyInterests]

[Edited on 1-6-2023 by ManyInterests]

[Edited on 1-6-2023 by ManyInterests]

[Edited on 1-6-2023 by ManyInterests]

[Edited on 1-6-2023 by ManyInterests]

ManyInterests - 31-5-2023 at 21:58

Yes, so I got a final yield of just 31ml at 44.58 grams. Giving it a specific gravity of 1.43806. This is around 75% nitric acid. I am not surprised it is at the upper end of the azeotrope.

Tomorrow I will try to lower the probe a bit more to see if I can get a better reading. Not too much, but just above where the flask starts.

Hey Buddy - 1-6-2023 at 11:32

This is similar to how I do it. The differences are, I generally prepare from NaNO3/NaHSO4 (because it is cheap). I use a cheap chinese burner with a ceramic dish on the heating mantle filled with sand, and I put the flask in the sand. The heater is plugged into a high temp thermal relay probe (cheap one) so the temp can be set at relay and the probe put in the sand which controls on/off for controlling sand bath temp. I use a cheap glass thermometer in the top of the three way adapter for monitoring distillation temp, and a straight tube condenser. Everything else is basically the same. I never recoded my yields in the beginning but I I think it is useful to have a little HNO3 record of yields for comparing over time. I usually do it in a garage with an open door. Over time, it corrodes pretty much everything and anything in the garage within around 40 ft. even with the door open and a small fan blowing. Metals that are galvanized or coated even with paint dont oxidize from transient nitro fumes as much. I have rusted a lot of tools doing it like this.

Rainwater - 1-6-2023 at 14:27

I think you have overestimated thread seal tape, youll need this soon
pt1000 replacement (part)
instruction video(kinda)

ManyInterests - 4-6-2023 at 18:39

No it isn't that. I attached a picture. The one marked in black is what I THOUGHT I had, the one marked in Green is what I actually had.

I could use a proper thermometer adapter in the former, but I made a mistake and I could not attach my condenser column to it. Once I get my hands on an adapter like that, it won't be an issue.

TOP-Advanced-Organic-Chemistry-Lab-Glassware-Kit-24-40-lab-Glassware-Kit-24-40.jp.jpg - 44kB

ManyInterests - 4-6-2023 at 19:03

In other news. I am going for a 2nd test run to see if I can get WFNA with the sodium nitrate I made... I think I will end up with another azeotrope. I am thinking that unless I get that adapter that I marked in black I will have to rely on older methods, as the temperature got up to 115 when I was getting acid.

But on a good note... I saw no red fumes for the first time, this means I had no wasted anything! Which is great.

Edit: I definitely need that joint! Only got 22.5ml of 81% HNO3. The distillation wasn't even done yet. The temperature control is now my main adversary. With that joint I can do a lot more.

[Edited on 5-6-2023 by ManyInterests]