Sulaiman
International Hazard
Posts: 3692
Registered: 8-2-2015
Location: 3rd rock from the sun
Member Is Offline
|
|
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
|
|
|
Magpie
lab constructor
Posts: 5939
Registered: 1-11-2003
Location: USA
Member Is Offline
Mood: Chemistry: the subtle science.
|
|
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,
|
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
|
|
|
wg48
National Hazard
Posts: 821
Registered: 21-11-2015
Member Is Offline
Mood: No Mood
|
|
| 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.
|
|
|
Sulaiman
International Hazard
Posts: 3692
Registered: 8-2-2015
Location: 3rd rock from the sun
Member Is Offline
|
|
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
___________________________________________________
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]
CAUTION : Hobby Chemist, not Professional or even Amateur
|
|
|
macckone
Dispenser of practical lab wisdom
Posts: 2168
Registered: 1-3-2013
Location: Over a mile high
Member Is Offline
Mood: Electrical
|
|
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.
|
|
|
Sulaiman
International Hazard
Posts: 3692
Registered: 8-2-2015
Location: 3rd rock from the sun
Member Is Offline
|
|
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
|
|
|
Texium
|
Thread Moved
26-2-2017 at 09:42 |
Sulaiman
International Hazard
Posts: 3692
Registered: 8-2-2015
Location: 3rd rock from the sun
Member Is Offline
|
|
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]
CAUTION : Hobby Chemist, not Professional or even Amateur
|
|
|
wg48
National Hazard
Posts: 821
Registered: 21-11-2015
Member Is Offline
Mood: No Mood
|
|
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.
|
|
|
Fulmen
International Hazard
Posts: 1716
Registered: 24-9-2005
Member Is Offline
Mood: Bored
|
|
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.
|
|
|
chloric1
International Hazard
Posts: 1140
Registered: 8-10-2003
Location: GroupVII of the periodic table
Member Is Offline
Mood: Stoichiometrically Balanced
|
|
| Quote: Originally posted by Sulaiman |
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
___________________________________________________
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] |
What temperature does magnesium nitrate completely become magnesium oxide? Since now have 40 lbs of calcium nitrate tetrahydrate, I should be able to
make MgO from Epsom salts. I want to play with magnesium cements. I already have a blast with white Portland cement, so easy to color!
Fellow molecular manipulator
|
|
|
Precipitates
Hazard to Others
Posts: 130
Registered: 4-12-2023
Location: SE Asia
Member Is Online
Mood: Acid hungry
|
|
From our wiki:
Magnesium nitrate decomposes at around 330°C+.
For specific details, this magnesium nitrate decomposition paper is quite extensive.
Given the findings of the paper, I'd whack the temperature up to 450°C, or higher, to speed up decomposition (you can't really go too high).
To avoid breathing in any of the nitrogen dioxide fumes produced perform the experiments outside - and in small increments (perhaps not pounds and
pounds of it at a time).
Keep heating until there is no further change in mass.
In the above study, the authors found this to be at around 500°C (773 K).
[Edited on 24-7-2024 by Precipitates]
|
|
|
chloric1
International Hazard
Posts: 1140
Registered: 8-10-2003
Location: GroupVII of the periodic table
Member Is Offline
Mood: Stoichiometrically Balanced
|
|
Hopefully magnesium oxide does not attack porcelain crucibles at 500 C because it’s like a matter of using a turrel or even a Meker burner. I hook
my burners to BBQ 20 lb propane so fuel last . I could opt for a using my nickel crucible or hammer a dish from hot rolled steel.
I might just try iron just to see if it gets passivated by the magnesium nitrate
Fellow molecular manipulator
|
|
|
![[*]](images/xpblue/default_icon.gif){kind=icon}
