Sulaiman
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Magnesium Nitrate for WFNA (not practical)
In preparation for making a little more anhydrous HNO3 I was searching eBay.uk for a suitable nitrate to use with
H2SO4 drain unblocker,
the best deal seems to be Mg(NO3)2 at £6.09 for 1kg inc. p&p.
Previously I have used Na, K, and Ca nitrates, Ca being the best value in terms of moles of nitrate per £,
Mg is even better, and MgSO4 is a lot more coluble than CaSO4 so should be better ?
I expect the Mg(NO3)2 to arrive in a few days so I will update this when I've actually made the HNO3
just thought I'd mention this in case anyone else is about to make some HNO3
and
using calcium nitrate, heat in the bottom of the distillation pot was much greater than at the top, visibly causing lots of NO2
this time I'd like to try a partial vacuum distillation,
can anyone recommemd an optimal vacuum pressure range to do this, using water near 0oC for the condenser ?
(e.g. @17mm Hg b.p. = 0oC = too low)
P.S. this page on nitric acid properties is informative http://nitrogen.atomistry.com/physical_properties_nitric_aci...
[Edited on 26-2-2017 by Sulaiman]
CAUTION : Hobby Chemist, not Professional or even Amateur
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Magpie
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Quote: Originally posted by Sulaiman  |
using calcium nitrate, heat in the bottom of the distillation pot was much greater than at the top, visibly causing lots of NO2
this time I'd like to try a partial vacuum distillation,
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Is that high temperature caused by solids laying in the bottom of the flask? If so, strong mechanical stirring should stop this.
Sucking off NO into your aspirator is a loss of yield.
The single most important condition for a successful synthesis is good mixing - Nicodem
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wg48
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| Quote: Originally posted by Sulaiman | In preparation for making a little more anhydrous HNO3 I was searching eBay.uk for a suitable nitrate to use with
H2SO4 drain unblocker,
the best deal seems to be Mg(NO3)2 at £6.09 for 1kg inc. p&p.
Previously I have used Na, K, and Ca nitrates, Ca being the best value in terms of moles of nitrate per £,
Mg is even better, and MgSO4 is a lot more coluble than CaSO4 so should be better ?
I expect the Mg(NO3)2 to arrive in a few days so I will update this when I've actually made the HNO3
just thought I'd mention this in case anyone else is about to make some HNO3
and
using calcium nitrate, heat in the bottom of the distillation pot was much greater than at the top, visibly causing lots of NO2
this time I'd like to try a partial vacuum distillation,
can anyone recommemd an optimal vacuum pressure range to do this, using water near 0oC for the condenser ?
(e.g. @17mm Hg b.p. = 0oC = too low)
P.S. this page on nitric acid properties is informative http://nitrogen.atomistry.com/physical_properties_nitric_aci... |
The price of Mg nitrate does look attractive but the only one I could find at that price looks like the dihydrate. That has a little less nitrogen (6%
with my quick calculation) but than its's almost half the price so still more economical.
But what about the two molecules water per nitrate, does it form an acid sulphate/hydrate. It would be nice if its prefers the hydrated sulphate in
the reaction conditions.
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Sulaiman
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Magpie,
yes, I expect that stirring would help, but my diy mantle/stirrer is not yet ready.
wg48
I am hoping that there will be much less NOx generated at the lower temperatures using partial vacuum.
side note: 10 minutes ago I started vacuuming my previous batch of RFNA at c -75 kpag to get WFNA .... results in an hour or so ....
....................................................................................
Oh crap ... I missed the fact that magnesium nitrate is hygroscopic and forms a hexahydrate ... my 1 kg of MgSO4 may be only 4 moles of
nitrate,
I'll cook it down to c600g of anhydrous magnesium nitrate before using it.
I dehydrated my calcium nitrate tetrahydrate, so no excuse for forgetting 
________________________________________________
result: ... rubber bungs don't like NOx / HNO3 ... D'oh
... not my day ... still learning ...
I've gone from nitric acid with a clear yellow colour to a cloudy orange
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To complete todays cock-ups ... magnesium nitrate hexahydrate cannot be dehydrated to even the dihydrate by heating...
it decomposes
2 Mg(NO3)2 → 2 MgO + 4 NO2 + O2
One batch of azeotropic nitric acid comming soon .......... 
(or maybe I'll keep the magnesium nitrate HEXAHYDRATE for something else and use my stock of Na, K or Ca nitrate)
[Edited on 26-2-2017 by Sulaiman]
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macckone
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Depending on rubber type,
You can actually get nitrated rubber.
Unlikely to be explosive but not good
for the rubber or the yield.
Get glass jointed equipment and
teflon sleeves instead of vacuum grease
for best results.
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Sulaiman
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I was lazy and just stuck a rubber bung in the bottle that I used to store the RFNA.
what pissed me off is that I KNOW that nitric acid attacks rubber 
I've always used glass only setups ... my pathetic excuse for forgetting
[Edited on 26-2-2017 by Sulaiman]
CAUTION : Hobby Chemist, not Professional or even Amateur
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Texium
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Thread Moved
26-2-2017 at 09:42 |
Sulaiman
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zts16
thanks for moving this ... maybe to detritus is more suitable ! ... please ... I can't bear the embarassment 
There is nothing new or useful in this thread ... it deserves 'detritusing'.
[Edited on 26-2-2017 by Sulaiman]
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wg48
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Oh crap ... I missed the fact that magnesium nitrate is hygroscopic and forms a hexahydrate ... my 1 kg of MgSO4 may be only 4 moles of
nitrate,
I'll cook it down to c600g of anhydrous magnesium nitrate before using it.
[Edited on 26-2-2017 by Sulaiman][/rquote]
I screwed up my calculation your right its probably the hexahydrate. Still a bit cheaper than sodium version per nitrate but a little bit too much
water for 68% nitric.
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Fulmen
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AFAIK it is virtually impossible to get anhydrous magnesium nitrate. It can in fact be used instead of sulfuric acid for nitration, dehydrated to
perhaps mono- or dihydrate.
We're not banging rocks together here. We know how to put a man back together.
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