Sciencemadness Discussion Board

The best way to produce sodium nitrate in this case?

Fyndium - 29-6-2022 at 12:14

I need sodium nitrate to be used with potassium nitrate as heating bath, and I already got the latter.

However, I had to make it too myself, and now I need to make NaNO3 as well. Only CAN is readily available, other nitrates must be ordered in large bags, which I am not intending to do because I do not need agricultural amounts, and sourcing reagent grade nitrates will be prohibitively expensive for this purpose.

What I have at my disposal is CAN, which was used as a source for KNO3. I obviously thought that it would likely be best to use Na2CO3 to mix with it, which will result in calcium carbonate crashing out, and sodium nitrate, ammonium nitrate and sodium carbonate in any traces or imbalances left in the solution.

The equation for CAN is following in converting it to KNO3:

NH4(NO3)*5Ca(NO3)2*10H2O + 11KCl = 11KNO3 + NH4Cl + 5CaCl2 + 10H2O

So there will be 1mol of AN for every 5mol of calcium nitrate.

Now the questions: Would the basicity of Na2CO3 be enough to decompose ammonium nitrate, or would I need to administer NaOH to take it out? The absolute purity would not be very critical, however of course always desirable. Also, how difficult is it to filter CaCO3 off using suction filtering with large glass frit filter?

B(a)P - 29-6-2022 at 12:53

Once you have removed the solid calcium carbonate heat the solution, the ammonium carbonate will crystallise out or decompose.

ManyInterests - 29-6-2022 at 13:25

Canadian Chemist among others have videos on using ammonium nitrate and CAN to make sodium nitrate. After filtering out the insoluble material from the cold pack they added sodium bicarbonate to it and mixed it, then heated it (outside, as boiling it will cause ammonia gas to form). After it completely dries you are left with sodium nitrate.

I used this myself recently. The yield was quite good, too. With 170 grams of nitrate from 190 CAN mixture.

I used the so-called 'ammonium nitrate' cold pack that I failed to get regular ammonium nitrate from.

clearly_not_atara - 29-6-2022 at 14:31

I'm pretty confident that the reaction between Na2CO3 and NH4NO3 will give sodium nitrate with no ammonium residue, as long as it is carried out above the decomposition temperature of bicarbonate, about 50 C.

ManyInterests - 29-6-2022 at 19:53

Quote: Originally posted by clearly_not_atara  
I'm pretty confident that the reaction between Na2CO3 and NH4NO3 will give sodium nitrate with no ammonium residue, as long as it is carried out above the decomposition temperature of bicarbonate, about 50 C.


I might give that ago myself some time then. I got plenty of sodium carbonate.

Fyndium - 29-6-2022 at 23:58

Now that you said it, AN + sodium carbonates should indeed form ammonium carbonate and sodium nitrate, which will escape as gas when in heated reaction, leaving mostly pure NaNO3 and CaCO3 behind.