Chisholm
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Solubility of salts in mixed acid
A recent change has required me to husband my NH4NO3, so I try as hard as possible to find substitutes for it in the generation of mixed acid in situ.
Where I live, sodium nitrate is considerably easier and vastly cheaper to acquire than potassium nitrate.
I attempted a synthesis that normally requires 300g anhydrous HNO3 and 450g of 98% H2SO4. Calculating that out gave me ~917g of 98%H2SO4 and 378g
NaNO3. Mixing the two while both warm (~50 C) gave...
...A big hunk of undissolved white matter that settled over the bottom of the beaker and entombed the stir bar like King goddamned Tut.
Some nitrate did dissolve; The choking white fumes were testimony to that. But yields in the subsequent nitration were abysmal. Even allowing for the
water produced by the reaction, almost no further dissolution of material occurred, and stirring the solution even at 15 Celsius was like stirring
half-dried applesauce.
What are the solubilities in grams per liter or grams per gram of NaHSO4 and KHSO4 in 98% H2SO4 at -5, 0, 20, & 25 deg Celsius?
[Edited on 4-2-2017 by Chisholm]
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Magpie
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I offer an alternative: assuming you have plenty of H2SO4 and NaNO3, make HNO3 first. Then you won't have to worry about those pesky salts and their
solubilities. In Prepublication I have posted a procedure for making HNO3 using KNO3. This should work OK with NaNO3 by substituting a mole of NaNO3
for a mole of KNO3.
The single most important condition for a successful synthesis is good mixing - Nicodem
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Chisholm
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Quote: Originally posted by Magpie  | | I offer an alternative: assuming you have plenty of H2SO4 and NaNO3, make HNO3 first. Then you won't have to worry about those pesky salts and their
solubilities. In Prepublication I have posted a procedure for making HNO3 using KNO3. This should work OK with NaNO3 by substituting a mole of NaNO3
for a mole of KNO3. |
Ordinarily I would do that, but I don't have access to my distillation equipment or vacuum pump at the moment.
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PirateDocBrown
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Where are you? In the US, NH4NO3 can be gotten in moderate amounts (1-2 kg) by mail order. Some gun stores sell it to make Tannerite.
I know what you are saying about NaNO3 vs. KNO3. Here, KNO3 is about 5-6 bucks a pound, but I can order NaNO3 for about $2 a pound.
I can also usually order CAN for ~$3 a pound or so.
[Edited on 4/2/17 by PirateDocBrown]
[Edited on 4/2/17 by PirateDocBrown]
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Chisholm
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| Quote: Originally posted by PirateDocBrown | Where are you? In the US, NH4NO3 can be gotten in moderate amounts (1-2 kg) by mail order.
I know what you are saying about NaNO3 vs. KNO3. Here, KNO3 is about 5-6 bucks a pound, but I can order NaNO3 for about $2 a pound.
I can also usually order CAN for ~$3 a pound or so.
[Edited on 4/2/17 by PirateDocBrown] |
When I buy NH4NO3, it's usually got dirt and specks of gravel in it, along with something vaguely brown that goes through my filters.
Also, technically NH4NO3 isn't converted to nitric acid in concentrated H2SO4 solution, it's dehydrated to nitramide (NH2NO2) first, which is then
hydrated by the nucleophile. That's why trying to distill HNO3 from sulfuric acid + NH4NO3 produces so much more NO2.
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PirateDocBrown
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Yes, I usually get the fertilizer grade nitrates, but have never had a problem recrystallizing them.
I make HNO3 from NaNO3, but it doesn't have to be terribly pure for this, especially since I'm using Rooto for the H2SO4.
Once the final product is gotten, I used to recrystallize out the NaHSO4, too, but haven't anymore, since I found that some pool pH Down is that
anyway. Old School, SaniFlush used to be NaHSO4 also, but it's off the market.
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