Sulaiman
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Calcium Nitrate water of crystalization removal
I intend to produce HNO3 for nitrations,
I already have 69% HNO3 but I want to try synthesizing it via
Ca(NO3)2 + H2SO4 = CaSO4 + 2HCl
and distilling it.
I bought 500g Calcium Nitrate, testing a little in a flame showed the presence of water, so;
I heated the entire 500g to remove the water of crystalization,
continuous aggitation/stiring/folding/crushing as suitable with a steel 1" scraper,
the c2mm dia. granules liquefied in their own water over about 10 min
simmering with steam evolving to a thick paste then granules, crushed to powder.
then more steam evolved and the powdered granules softened by the steam formed new clumps,
this second 'clumping' formed harder granules than earlier.
after long continuous heating the powder/granules gave of very little steam
I tested a small amount in a flame and saw no water so
after cooling for c5 min. the product was sealed in the original HDPE bottle with pvc tape.
The heat was applied continuously, sorry, no suitable thermometer, cheap electric hotplate OFF-1-2-3-4-5.
setting slowly increased when it seemed appropriate, final drying at 5 for c30 min. total drying time c 2.5 hours.
Nett product 420g, looked like about 1g lost due to splashes/leaping granules etc.
Theoretically 500g of (assumed) heptahydrate should yield 347g anhydrous
but if heptahydrate to dihydrate 423.3g which is close
(all weight measurements using 1g resolution cheap kitchen scales)
SO
if it was 'pure' Calcium Nitrate I probably have 420g of the dihydrate,
if the Calcium Nitrate was 'fertilizer grade' it may have ammonium nitrate as an impurity
(ironic as it is because of the 'ban' on the easy nitrates that I'm using calcium nitrate
and ammonium nitrate is a possible 'contaminant')
I want to heat the (presumed) dihydrate to anhydrous,
1M NaOH produces bubbles but no ammonia (smell, litmus, HCl fumes)
do I need to check further for ammonium nitrate?
Edit: and, is there any chance of calcium nitrate exploding on heating?
such a noob question ... but i am a noob and maybe over cautious
but 500g of a nitrate is what I call a lot.
[Edited on 26-4-2015 by Sulaiman]
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blogfast25
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Quote: Originally posted by Sulaiman  | I want to heat the (presumed) dihydrate to anhydrous,
1M NaOH produces bubbles but no ammonia (smell, litmus, HCl fumes)
do I need to check further for ammonium nitrate?
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Try mixing your product with some NaOH ('pure'), add a bit of water and heat moderately: if you still can't smell any NH<sub>3</sub> you
can be sure your source material didn't contain any ammonium salts.
First successful transmutation of N to Cl reported at SM! 
[Edited on 26-4-2015 by blogfast25]
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bolbol
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3 grams of difference doesnt really indicate much, your outcome wont be 100% identical to your stoicheometry. Also it couldve been a mix of different
hydrates but I highly doubt it.
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Gargamel
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I recently did this.
A real pita.
It tended to crust at the bottom but the lumps on top where still wet.
I think decomposition occurs somewhere around 500°C so one has to be careful not to overheat it.
In the end I had to scrape the stuff out of the pot.
I tried a well prooven nitration mix and decanted the clear liquid with small losses, only the nitration produced very little ETN, most was water
soluble.
Somehow the concentration must have been insufficient, or I used to much erythritol.
Further testing needed. Big advantage: You can use a magnetic stirrer, no sulfate slurry.
| Quote: |
is there any chance of calcium nitrate exploding on heating |
I don't think so.
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papaya
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Convert it to sodium or potassium nitrate first (via according sulfate or carbonate) and only then use it for what you need.
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Sulaiman
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oops !
I of course meant HNO3 not HCl ..... stupid mistake ... brain not in gear ... sorry!
Thanks for all of the replies,
papaya;
"Convert it to sodium or potassium nitrate first (via according sulfate or carbonate) and only then use it for what you need"
... none of the above in my stock, I'll think about this for future reference, thanks.
...........................................................................
Gargamel;
"I recently did this.
A real pita.
It tended to crust at the bottom but the lumps on top where still wet.
I think decomposition occurs somewhere around 500°C so one has to be careful not to overheat it. "
More cooking tomorrow .... I'll stop when traces of NO2 are detected.
P.S. Anyone have opinions on removing water of crystalization by
heating over a hot plate vs. in a domestic oven vs. in a microwave oven?
[Edited on 27-4-2015 by Sulaiman]
[Edited on 27-4-2015 by Sulaiman]
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AJKOER
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A completely different approach, the dry salt can, I suspect, be directly prepared by the action of NO2 (and, at times, with select metals and
reaction conditions, in combination with O2 also) on the metal oxide:
CaO + 3 NO2 = Ca(NO3)2 + NO
(which, in one embodiment of the reaction, the oxide is on the skin of a large sheet of Calcium metal, permitting a easy physical separation of the
nitrate product)
Or possibly, the net reaction:
CaO + 2 NO2 + 1/2 O2 = Ca(NO3)2
which would be similar to that reported for AgNO3, as an example.
Wikipedia http://en.m.wikipedia.org/wiki/Nitrogen_dioxide as a source, on the first reaction, to quote:
"NO2 is used to generate anhydrous metal nitrates from the oxides:[8]
MO + 3 NO2 → M(NO3)2 + NO
Alkyl and metal iodides give the corresponding nitrites:
2 CH3I + 2 NO2 → 2 CH3NO2 + I2"
To support my second claimed reaction, note:
NO + 1/2 O2 → NO2
and, upon adding oxygen to both sides of MO + 3 NO2 → M(NO3)2 + NO, and substituting per above, we have:
MO + 3 NO2 + 1/2 O2 = M(NO3)2 + NO2
or, upon removing one of the regenerated NO2 (assuming the NO plus oxygen has not been removed from the reaction environment), the net reaction may
approach:
MO + 2 NO2 + 1/2 O2 → M(NO3)2
as I claimed. Here is a reference with respect to my AgNO3 example, per "Interaction of Silver with a NO/O2 Mixture: A Combined X-ray Photoelectron
Spectroscopy and Scanning Electron Microscopy Study" by D.Y.Zemlyanov, et al., where to quote from the abstract: "whereas AgNO3 resulted from the
subsequent reaction of Ag2O with NO2 in the gas phase.", link: https://www.google.com/url?sa=t&source=web&rct=j&... . Note this example suggests that one can choose to directly generate the more
safe NO (in place of NO2), and mix with O2, to form the anhydrous metal nitrate.
Also, in the presence of a limited amount of moisture, the following reaction should be noted creating Nitric acid and nitrate:
4 NO2 + O2 + 2 H2O = 4 HNO3
[Edit] Here is a reference to the feasibility of the NO2 (or NO/O2) approach via some accidental formation of anhydrous Aluminum nitrate reported on
SM at http://www.sciencemadness.org/talk/viewthread.php?tid=22790 shown below:
| Quote: Originally posted by Antiswat |
[/rquote]
What I found interesting was that anhydrous aluminum nitrate can be prepared from AlCl3 in N2O4 at 0 °C.
[Edited on 23-12-2012 by AndersHoveland][/rquote]
A bit off topic, but when ive made Pb(NO3)2 by HNO3 + Pb i have covered my flask with 10 layers of aluminium foil, and apparently the NO2 formed can
and WILL react with the aluminium foil to make aluminium nitrate, infact this reaction is probably taking place right now, just thought its weird that
aluminium wont react with HNO3 but NO2 reacts with aluminium |
[Edited on 28-4-2015 by AJKOER]
[Edited on 28-4-2015 by AJKOER]
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Magpie
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I'm assuming your goal is to make azeotropic nitric acid which is 68wt% and that you have calcium nitrate tetrahydrate and 96wt% H2SO4 to do this. On
this basis I wouldn't bother trying to make the Ca(NO3)2 anhydrous.
Ca(NO3)2*4H2O + H2SO4 +0.042 H2O ---> CaSO4 +2HNO3 + 4.042 H2O
excluding the CaSO4 ppt, the fraction HNO3 = (2)63/[2(63) + 4.042(18.02)] = 126/198.8 = 0.634
Therefore, the wt% acid before distillation will be 63.4%. During distillation the acid coming over will be rich in water until the azeotropic
composition is reached (68% HNO3). At this point you change receivers. Distillate temperature tells you when this point is reached. From then on
the condensate will be the azeotrope. See:
http://chemwiki.ucdavis.edu/Physical_Chemistry/Equilibria/Ph...
The CaSO4 may take on water as a hydrate so this would work in your favor.
I have never tried this but I think you will get mostly azeotropic acid using the hydrate "as is."
The single most important condition for a successful synthesis is good mixing - Nicodem
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Varmint
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Adding to Magpie:
Always retain the early distillate in a common container, when time is available do a careful re-distillation and bottle the concentrate AND the early
distillate again.
The premise is, we are paying a premium in currency and time for HNO3, so tossing any amount down the drain or otherwise discarding seems like a waste
of time and money.
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