Siddy
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Sodium Nitrate synthesis. NaCl + HNO3
Hi,
Im after a neat synthesis for Sodium Nitrate.
Ive come up with this, but would appreciate some input before i use my ID to buy the HNO3.
Or does anyone know where Sodium Nitrate can usually be bought/extracted from?
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UnintentionalChaos
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If you can buy HNO3, it should be very easy to find NaNO3. Look for it as a fertilizer in garden stores. I can buy it by the 5 pound box for $8 US. It
requires minimal processing to get fairly high purity material.
If you feel like doing some simple chemistry, you can mix ammonium nitrate with sodium hydroxide in aqueous solution in a 1:1 molar ratio, and boil
until ammonia stops coming off, reduce the solution volume, and cool to crystallize the product.
NH4(NO3) (aq) <-> NH4+ (aq) + NO3- (aq)
NaOH (aq) <-> Na+ (aq) + OH- (aq)
NH4+ (aq) + OH- (aq) <-> NH3 (g) + H2O (l)
By boiling off the ammonia gas in the last equation, you drive the reaction to the right, pushing it until effectively no more ammonium ions are
present.
Through some slightly more complex equilibrium reactions, sodium carbonate could also be used, but would be quite a bit slower, I imagine.
[Edited on 10-9-07 by UnintentionalChaos]
Department of Redundancy Department - Now with paperwork!
'In organic synthesis, we call decomposition products "crap", however this is not a IUPAC approved nomenclature.' -Nicodem
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Siddy
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Thanks for the reply, ill keep looking.
Could you reference a purification method?
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UnintentionalChaos
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Mine comes as white prills. I dissolve in water to make an almost saturated solution, filter through cotton to remove insoluble scum, leaving an
almost completely colorless, clear liquid, boil down solution volume by at least half in an oven and allow to cool, at which point plenty of crystals
form in the evaporating dish. I pour off the extra liquid, break up the crystals and rinse once with a little ice water to remove any more of the
solution and bake at around 350F until the slight sizzling sound of water boiling off stops. All the rinse water is collected, mixed with the original
excess liquid, and boiled down again, and the other steps repeated until there is too little of it left to bother with (or it gets too discolored
looking), at which point I use it on the garden since it is a cheap chemical. Essentially a simple recrystallization procedure. I've hot filtered a
lot of solutions and the solubility curve of nitrates makes it completely worthless to even bother. I gravity filter my solutions when possible since
it does a better job at removing small particles and the nitrates start to crystallize way too fast to make it efficient.
Repeat the whole process with the product you got if you are REALLY neurotic about purity.
Oh, and check the pH of the solution. It should be neutral. If it isn't there is some excess nitric acid in there and you should add sodium
carbonate/bicarbonate/hydroxide until it is neutral.
BTW this should have been posted in beginnings or chemistry in general.
[Edited on 10-9-07 by UnintentionalChaos]
Department of Redundancy Department - Now with paperwork!
'In organic synthesis, we call decomposition products "crap", however this is not a IUPAC approved nomenclature.' -Nicodem
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Siddy
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Thanks for the method.
Yeah, it should have been in general chem. It was my first post.
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MagicJigPipe
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And I would never buy HNO3. Way to easy to make with KNO3 and H2SO4 distillation. Use all glass/PTFE though!
And it would be a round about way but you could just neutralize the HNO3 with baking soda or NaOH to get the NaNO3.
Oh yeah, general chem... Well, at least he wasn't chastised...
[Edited on 19-10-2007 by MagicJigPipe]
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