Sciencemadness Discussion Board

Strontium nitrate from strontium carbonate

underground - 10-2-2020 at 07:37

I just got some Sr carbonate and tried to make some Sr nitrate with ammonium nitrate. I measured out 400g of Sr(NO3)2 and 450g of AN. AN dissolved and heated up, then SrCO3 was added. The weird thing is that i could not smell any ammonia so no reaction took place, and after i dried the mixture, i added some HNO3 and bubbling occurred so it is still mostly Sr carbonate. Any idea why the reaction did not work?

Tsjerk - 10-2-2020 at 08:07

The carbonate has to dissolve in order for it to react with ammonium. Strontium carbonate is pretty insoluble with 0.065 g/100 mL (100 °C). This process will probably work, but you need to reflux for a very long time.

Apparently the carbonate is a bit soluble in ammonia. Ammonia is produced in the process, what I read is that the recommended procedure is to slowly add hot ammonium nitrate solution to a hot suspension of SrCO3. Maybe the ammonium nitrate pushes the carbonate out of solution. I don't know. What you could do is refluxing what you have now with a bit of dilute ammonia.

Or just use the nitric acid directly, but that is probably not preferable.

underground - 10-2-2020 at 08:21

Ok i will try it out

Edit:

What if i react a stoichiometric amount of AN and HCL to form NH4CL and HNO3? Then add the Sr Carbonate? I then just have to separate the NH4CL from Sr nitrate, maybe by decomposing NH4CL

[Edited on 10-2-2020 by underground]

Tsjerk - 10-2-2020 at 09:18

The problem with that would be the formation of nitrosyl chloride, which is pretty stable and hard to get rid off.

symboom - 10-2-2020 at 09:29

You might have to convert it to strontium hydroxide the reaction will be the same as calcium hydroxide forming calcium carbonate and ammonia gas as side products
The method you were hoping to work is with sodium carbonate and ammonium nitrate where ammonium carbonate is produced and driven off by high temperature.

underground - 10-2-2020 at 11:10

Quote: Originally posted by symboom  
You might have to convert it to strontium hydroxide the reaction will be the same as calcium hydroxide forming calcium carbonate and ammonia gas as side products
The method you were hoping to work is with sodium carbonate and ammonium nitrate where ammonium carbonate is produced and driven off by high temperature.


So if i react of Sr carbonate with NaOH, how i get out the Na carbonate?
Quote: Originally posted by Tsjerk  
The problem with that would be the formation of nitrosyl chloride, which is pretty stable and hard to get rid off.



nitrosyl chloride is a gas so by evaporating everything you should get rid of it right ?

[Edited on 10-2-2020 by underground]

Tsjerk - 10-2-2020 at 12:38

Quote: Originally posted by underground  


nitrosyl chloride is a gas so by evaporating everything you should get rid of it right ?

[Edited on 10-2-2020 by underground]

I'm not an expert on nitrosyl, but you could have a look at Woelen's posts about it. It is not a gas as you think it as as long as water is around.

woelen - 10-2-2020 at 13:03

Nitrosyl chloride is an orange/brown gas, which can exist in concentrated HCl as a bright orange solution. On dilution, this gas is hydrolyzed by the water, forming HCl and HNO2. The HNO2 in turn slowly decomposes, giving NO and HNO3.

I personally think that ONCl is not a real problem in the above reaction. But I see no point in adding chloride in the mix as well. You make things more complicated and more difficult to separate.

What you can try is dissolving SrCO3 in dilute HCl and boiling this down to a very saturated solution of SrCl2.
NH4NO3 also is very soluble.
If you mix the solutions (using a little excess NH4NO3) and boil down, then the first compound to precipitate may be Sr(NO3)2. This is the least soluble. Do not expect a nice pure product though. You'll need at least one recrystallization for a reasonably pure product.

symboom - 10-2-2020 at 13:06

I was assuming to much thermal decomposition of strontium carbonate to strontium oxide then add water to form strontium hydroxide

underground - 10-2-2020 at 13:50

This reaction takes place at a temperature of 1100-1200°C.
Quote: Originally posted by woelen  
Nitrosyl chloride is an orange/brown gas, which can exist in concentrated HCl as a bright orange solution. On dilution, this gas is hydrolyzed by the water, forming HCl and HNO2. The HNO2 in turn slowly decomposes, giving NO and HNO3.

I personally think that ONCl is not a real problem in the above reaction. But I see no point in adding chloride in the mix as well. You make things more complicated and more difficult to separate.

What you can try is dissolving SrCO3 in dilute HCl and boiling this down to a very saturated solution of SrCl2.
NH4NO3 also is very soluble.
If you mix the solutions (using a little excess NH4NO3) and boil down, then the first compound to precipitate may be Sr(NO3)2. This is the least soluble. Do not expect a nice pure product though. You'll need at least one recrystallization for a reasonably pure product.



Ok i will try this out


Edit:

From the above reaction, Sr(NO3)2 and NH4CL will be formed. How should i separate them as they both got identical solubilities ?

[Edited on 10-2-2020 by underground]

Bedlasky - 10-2-2020 at 15:02

They haven't identical solubilities.

underground - 10-2-2020 at 15:06

According to wiki Sr(NO3)2 got 604.3 g/L (0 °C) and NH4CL 294 g/L (0 °C) so it is not that much big difference.

CharlieA - 10-2-2020 at 18:22

In the supplement to his "Illustrated Guide to Home Chemistry Experiments," Robert Bruce Thompson (aka The Home Scientist) started with crude strontium carbonate from Seattle Pottery, washed it with water several times to remove any soluble impurities, and then converted it to strontium with HCl (by products are carbon dioxide and water). The strontium chloride is then reacted with sodium hydroxide to give the insoluble strontium hydroxide and sodium chloride. The insoluble strontium hydroxide is reacted with nitric acid to give strontium nitrate and water. The strontium nitrate is then recovered by evaporation.

This sounds convoluted, but it is mostly tedious. Each step gives a strontium compound easily separated from the other products produced in the reaction. So each step should give a high percentage yield of the desired product.

As an aside, why did you expect to smell ammonia (NH3) from your reaction? From your procedure, barring impurities in your chemicals and perhaps some hydrolysis of ammonium ion, I wouldn't expect to smell any ammonia.

clearly_not_atara - 10-2-2020 at 20:12

I don't know why all of these strange ideas are necessary. The simple method should work fine. It's just a long reflux. And it's much cheaper and easier than breaking out the hydrochloric acid.
Quote: Originally posted by symboom  
You might have to convert it to strontium hydroxide the reaction will be the same as calcium hydroxide forming calcium carbonate and ammonia gas as side products


This is far more difficult than simply reacting SrCO3 with a refluxing solution of NH4NO3. SrCO3 decomposes at a whopping 1494 C! That's 500 degrees hotter than limestone.
Quote:
What you can try is dissolving SrCO3 in dilute HCl and boiling this down to a very saturated solution of SrCl2.
NH4NO3 also is very soluble.


SrCl2 solubility 53.8% w/w, Sr(NO3)2 solubility 66% w/w; SrCl2 molar mass 158, Sr(NO3)2 molar mass 211. Molar solubilities 3.4 M and 3.1 M respectively.

That's sliding in right under the wire for salt metathesis and I don't know how the solubility of SrCl2 changes with temperature. It could work or not. NH4Cl however has a molar solubility of about 5.5 so it's nothing to worry about.



[Edited on 11-2-2020 by clearly_not_atara]

UC235 - 10-2-2020 at 20:45

I have precipitated Sr(OH)2 before. Solubility is 0.41g/100ml ice cold and it comes out as the octahydrate. If the SrCO3 is pottery grade it may also contain some barium. Preparing the chloride solution and dropping out the hydroxide constitutes a purification step since Ba(OH)2 is somewhat more soluble.

The hydroxide should be more than soluble enough to readily react with NH4NO3.

underground - 11-2-2020 at 05:34

I want to use the Sr nitrate for pyro purposes so i guess i should use KOH right ?

Tsjerk - 11-2-2020 at 06:32

If you want a nice red, sodium is a no go as long as you're not prepared to do laborious recrystallisations.

underground - 11-2-2020 at 14:38

After searching around a bit, i have seen ppl got Barium nitrate from carbonate with the same method while it is less soluble than Sr Carb. Also, here tetrahedron use AN and Sr carbonate to make Sr Nitrate. It is really strange why my reaction does not work. Also, i noticed a bit of sulfur smell why i was trying for it. The AN is a fertilizer grade.

Tsjerk - 12-2-2020 at 03:58

Where does your carbonate come from? Maybe it is calcinated and therefore a bit less reactive. I'm pretty sure you just didn't give it enough time. How long did you reflux?

woelen - 12-2-2020 at 06:11

In my previous reply I assumed that you don't want to use (precious) nitric acid for this purpose, hence the somewhat involved mechanism through SrCl2. If you are willing to spend some nitric acid, then things of course are much easier.

underground - 12-2-2020 at 06:44

Yea i don't actually want to spend my few ml of HN03. I did a mixture of 450g of 35% HCL and 400g of moistened AN. The mixture was pretty cold due to AN dissolved into it. No heat up built at all. When almost all AN dissolved, i used a sample of that mixture to react with some copper metal and no reaction occurred. Obviously something is wrong with that AN. Maybe they have added additives to make it unreactive or i dunno. If it did not react with HCL then there is no possibility to react with Sr Carb.



[Edited on 12-2-2020 by underground]

Tsjerk - 12-2-2020 at 08:38

High concentration of chloride in aqua regia can lead to passivication. The fact the dissolution of your presumed AN leads to cooling of the solution makes me think it is actually AN. What else is endothermic upon dissolving and what could possibly interfere in this reaction?

Again: my bet is on calcinated SrCO3 and a too short reaction time.

I will ask again; how long did you reflux during the first experiment?

Edit: if you refluxed at all.

[Edited on 12-2-2020 by Tsjerk]

[Edited on 12-2-2020 by Tsjerk]

underground - 12-2-2020 at 10:41

I have not a reflux device just boil it, add water and continue boilling it. About 5h

woelen - 14-2-2020 at 00:15

Are you sure that the material in the cold pack is ammonium nitrate? In many countries, this is replaced by urea. The latter also works quite well for cooling purposes and dissolves in water very well. I get the impression that you cold pack is urea instead of ammonium nitrate.

Ammonium nitrate + conc. HCl definitely is capable of dissolving copper metal. Copper metal is one of the metals, which is not passivated by a strongly oxidizing solution.

You could test for urea as follows:
- Heat the material until it melts, but do not overheat, just keep it in a molten state.
- the material will lose gas (bubbling).
- You will smell ammonia, quite a lot of it.
- Keep the white residue. Let it cool down, crunch to a fine powder, and dissolve in water (no problem if not all of it dissolves)
- Perform the so-called biuret test: https://en.wikipedia.org/wiki/Biuret_test
You can do this test without the tartrate, mentioned in the wiki page. Just use copper sulfate and a little alkali, you will see the purple color if the original material is urea.

underground - 14-2-2020 at 02:14

It is a fertilizer grade and i asked about AN, there is another urea fertilizer so i really doubt it is Urea.

I just got another idea, i may react NAOH and CaCL to form the insoluble CAOH. React CAOH with AN to form CA nitrate. React h2so4 with Ca nitrate to form the relative insoluble Ca sulfate and hno3. Filter it and react with Sr carb to form Sr nitrate. It may contain a few calcium sulfates as impurities but it won't matter cause it is for pyro purposes. Ca and Sr got almost the same color.

CaHO should easily react with AN. If it won't then i definitely have to toss it lol


[Edited on 14-2-2020 by underground]

woelen - 14-2-2020 at 02:40

You should be a little more precise in your usage of chemical symbols and formulae. That makes your posts look much better.

NaOH and CaCl2 may react to form solid Ca(OH)2. Solid Ca(OH)2 is fairly soluble in water, but less so than NaOH and CaCl2. Getting the pure chemical, free from chloride will not be really easy, but indeed, it may be a nice pathway to what you want. You do not have to isolate and dry the Ca(OH)2, just having a slurry in water is OK. If you precipitate this compound, then briefly rinse it with water, otherwise you may lose too much, because it is somewhat soluble in water.

There is one difficulty, and that is finding the right amount of H2SO4 to be added to your Ca-nitrate. The best thing most likely is mixing small amounts of acid in multiple steps with the resulting slurry of CaSO4 and stirring and taking a drop of the clear liquid, which you put in a solution of CaCl2 for testing on sulfate ion. I would try to avoid excess of H2SO4, so as soon as the test for sulfate is positive, you add a little of your Ca-nitrate solution again (so, you must keep a small amount of that aside for the final correction). If your HNO3 contains excess H2SO4, then it may severely impede the reaction of the SrCO3, due to formation of an insoluble coating of SrSO4 around the SrCO3 particles. Having a slight amount of calcium in your final product is not a problem, because Ca-ions also give a reddish color (and this color will be completely washed out by the brighter red of the Sr-ions).

If your supposed to be ammonium nitrate material does not react with Ca(OH)2, then it is not ammonium nitrate.

[Edited on 14-2-20 by woelen]

underground - 14-2-2020 at 04:09

Thanks for your input woelen

BTW, i got 30% H2SO4, is this going to work or i have to use concentrated?


[Edited on 14-2-2020 by underground]

Tsjerk - 14-2-2020 at 05:08

30% is more than sufficient. You could use the 30% for the first 75% of the acid to add, but I would dilute it to let's say 10% for the titration described by Woelen, otherwise you will easily overshoot.

underground - 14-2-2020 at 07:12

Ok i understant the concept thanks a lot