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Author: Subject: Diluting 90+% Nitric Acid to 70%?
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[*] posted on 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?
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[*] posted on 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]
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[*] posted on 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
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[*] posted on 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]
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[*] posted on 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.
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[*] posted on 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!
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[*] posted on 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.
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[*] posted on 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.
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[*] posted on 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]




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[*] posted on 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! :D

[Edited on 27-6-2022 by ManyInterests]
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[*] posted on 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! :D

[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
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[*] posted on 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




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[*] posted on 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]
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[*] posted on 4-8-2022 at 13:19


How did you determine the concentration of the sulfuric acid?
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[*] posted on 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.
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[*] posted on 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.
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[*] posted on 5-8-2022 at 14:14


Quote: Originally posted by ManyInterests  
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.


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.:)
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[*] posted on 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 20oC.

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.
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[*] posted on 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.




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[*] posted on 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?
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[*] posted on 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.




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[*] posted on 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]
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[*] posted on 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.



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[*] posted on 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.
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[*] posted on 24-5-2023 at 06:31


you could use dilution calculation to dilute the HNO3


dilution calculations .png - 85kB
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