Sciencemadness Discussion Board

Nitric acid from calcium nitrate

Chemgineer - 8-6-2024 at 15:55

I normally produce nitric acid from magnesium nitrate and sodium bisulfate dry distillation and it works great.

I have however allot of calcium nitrate I want to use but the Nurdrage procedure for the distillation of this with sodium bisulfate works great but erodes chunks of glass from my flasks and breaks them!

Do you think I should be converting the calcium nitrate to another nitrate salt to avoid this or would a wet distillation of calcium nitrate and sodium bisulfate be better.... with a fractional distillation of the nitric acid later?

Rainwater - 8-6-2024 at 18:32

CaSO4 is a real pain in the !@@ to clean. I experienced glass etching with sodium metabisulfate and CaNO3
It was only noticeable after 3~4 runs
And again with potassium bisulfate(leftovers from making HNO3 via sulfuric acid & potassium nitrate)

I think its the little bit of water trapped in the salt that lets it eat glass if at any point a hydroxide forms.

Chemgineer - 9-6-2024 at 05:01

Quote: Originally posted by Rainwater  
CaSO4 is a real pain in the !@@ to clean. I experienced glass etching with sodium metabisulfate and CaNO3
It was only noticeable after 3~4 runs
And again with potassium bisulfate(leftovers from making HNO3 via sulfuric acid & potassium nitrate)

I think its the little bit of water trapped in the salt that lets it eat glass if at any point a hydroxide forms.


Yes always 3-4 runs before it starts, making you think everything will be fine! Perhaps the first few runs allow some calcium sulfate to stick to the glass and get a better adhesion on the later runs.

Hmm I wonder if it would help to alternate between magnesium nitrate anc calcium nitrate runs, would this help to clean the flasks?

Rainwater - 9-6-2024 at 07:42

Quote: Originally posted by Chemgineer  
would this help to clean the flasks?

Not sure, a 20 minute boil in hot water usually breaks up and softens the larger chunks of plaster. My problem is getting the rbf absolutely clean. No matter how many times i wash it, there is always a little caso4 still left in there. Washing with hot diluted H2SO4(~5%) does the trick.

fx-991ex - 9-6-2024 at 08:00

I may be wrong but i think calcium ion are known to attack glass.

Sir_Gawain - 9-6-2024 at 09:28

Do a double displacement with sodium carbonate.

charley1957 - 9-6-2024 at 09:29

I have a container of steel BBs at the sink where i wash my glassware. Swirling/shaking them around in the flask works wonders to help break up stuck-on stuff. Saves acid too.

Rainwater - 9-6-2024 at 18:12

Charley, you are a genuine genius. And its simple, love it

Chemgineer - 10-6-2024 at 07:04

Quote: Originally posted by Sir_Gawain  
Do a double displacement with sodium carbonate.


Thanks, that is probably the best idea as long as calcium carbonate settles out of the solution nicely.

fx-991ex - 10-6-2024 at 07:59

Quote: Originally posted by Chemgineer  
Quote: Originally posted by Sir_Gawain  
Do a double displacement with sodium carbonate.


Thanks, that is probably the best idea as long as calcium carbonate settles out of the solution nicely.

Yes it do and its very easy to filter too.

fx-991ex - 10-6-2024 at 08:00

Quote: Originally posted by charley1957  
I have a container of steel BBs at the sink where i wash my glassware. Swirling/shaking them around in the flask works wonders to help break up stuck-on stuff. Saves acid too.

I do the same thing but i use coarse salt instead loll, i guess sand could work well too.

Chemgineer - 14-6-2024 at 13:09

Does this sound reasonable volumes for double displacement of sodium nitrate from calcium nitrate using sodium carbonate?

120g Na2CO3 in 300ml water
185g Ca(NO3)2 (not anhydrous) in 100ml water

Should produce 190g of NaNO3 in 400ml of water once the calcium carbonate is filtered off.

Or should I add my 300ml solution of sodium carbonate directly to my calcium nitrate prills and heat and mix ending up with only 300ml volume with less boiling down needed?

fx-991ex - 14-6-2024 at 13:45

Make sure your Ca(NO3)2 are in fact Ca(NO3)2 and not CAN calcium amonium nitrate.
If its CAN then:
For 120g of Na2CO3 you should use 222g of CAN to get 192g of NaNO3, 103g CaCO3, 37g H2O, 10g (NH4)2CO3(will decompose upon heating to recrystallize).

If your Ca(NO3)2 is indeed pure then the ratio/weight are correct.
Just use as little water as possible.

Id avoid pouring the Na2CO3 sln into the Ca(NO3)2 prill, you may want to filter the Ca(NO3)2 sln before rxn.

Alkoholvergiftung - 14-6-2024 at 22:30

The test for CAN should be easy. In Aceton 1l disolve 330g Calciumnitrate and only 1g ammoniumnitrate. Would be a seperation methode too.

[Edited on 15-6-2024 by Alkoholvergiftung]

Fulmen - 15-6-2024 at 01:35

The simplest test for CAN is to mix it with sodium hydroxide in solution. CAN will give off ammonia.

greenlight - 15-6-2024 at 09:33

You could also convert the calcium nitrate to potassium nitrate with potassium chloride if that's easy to find in your country. Potassium chloride can be brought in large quantities in some places as water softener.
Then you have nitrate salt thats easier to dry and keep dry as it is not hygroscopic like sodium nitrate.

Distillation with concentrated sulfuric acid and done:)

fx-991ex - 15-6-2024 at 11:57

Quote: Originally posted by greenlight  
You could also convert the calcium nitrate to potassium nitrate with potassium chloride if that's easy to find in your country. Potassium chloride can be brought in large quantities in some places as water softener.
Then you have nitrate salt thats easier to dry and keep dry as it is not hygroscopic like sodium nitrate.

Distillation with concentrated sulfuric acid and done:)


It work but purity will be better with KOH, or he could just re-crystallize twice of course.

Chemgineer - 21-6-2024 at 06:33

Yeh I produced some sodium nitrate as above but it's not convenient to use since it is so hygroscopic.

ManyInterests - 13-9-2024 at 16:12

I actually do have one question about this. I have 15.5 calcium nitrate (meaning it has a small amount of ammonium nitrate in it as well) and knowing that the calcium sulfate is a giant PAIN to get rid of, I did think about cleaning it from the potassium or sodium sulfates as well...

Since when I make nitric acid, whether I use sodium nitrate or potassium nitrate (further dried in the oven before hand in order to drive away any water that it might have absorbed) getting rid of the sulfate cake after it cools is still an hours long process and I use a lot of sodium bicarbonate or carbonate to get it clean and dissolved. Even though those sulfates are supposed to be water soluble they don't appear to be so, but just using a basic solution to get them to dissolve is what is needed.

Am I doing something wrong here? Because the biggest issue I have with making nitric acid is the clean up afterward. I always wash all my gear and let them air dry between runs, but it would be MUCH easier if I can get my flask cleaned up quicker.

The other issue is that the specific gravity of my nitric acid rarely seems to be in the WFNA ratio, but I am being told not to rely on that. So going forward I will see if I can make PETN and RDX with the acid I make, but cleaning the flask more easily would be a great boon.

Any help?

Rainwater - 13-9-2024 at 16:38

I find it much easier to perform a wet distillation and then use sulfuric acid to remove the water.
It is easy to clean so long as the byproducts are not heated until molten, and the sulfuric acid is recoverable. To the best of my knowledge, calcium sulfate can not be easily cleaned.
If you could keep water out of the mix (baking reagents before use), you might be able to use a modified pressure cooker to make a dry distillation appratus.
Aluminum would be a good choice.
Sodium sulfate's only really eat into aluminum in the presence of water, and nitric acid will simply passivate it.
It would be a disposable appratus but should survive many runs.

ManyInterests - 14-9-2024 at 12:08

Quote:
I find it much easier to perform a wet distillation and then use sulfuric acid to remove the water.


I must agree with this. So far I have not done a redistillation, I usually distill as dry as possible and hope for the best. Sometimes I succeed, but other times not so much. Nurdrage distills his nitric acid with 1:1 ratio of sulfuric acid, but I was told that an excess of even twice as much sulfuric acid will be much better.

For me in order to make it worth it, I need to make several distillations of nitric acid before redistilling everything and collecting. I have a 2 liter boiling flask that I use mostly for this, and two runs will allow me to have around 450 to 500ml (if I am lucky) to redistill. Three runs would requirement to use a 1 liter receiving flask.

The use of improvised distillation equipment is a no-go for me. I got dedicated stuff and I really don't want to waste any more money. Especially on things like pressure cookers which can get pricey.