Fantasma4500
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Registered: 12-12-2012
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simple airtight HNO3 proof setup??
ive tried now twice without luck to distill HNO3 by H2SO4 + HNO3
there is conc. HNO3 in the mix, thats for sure...
but im loosing pressure all the time..
i have tried 2 things now
1. 250 mL tall beaker with smaller beaker inside (100 mL)
top covered with thick layers of aluminium foil shaped as a cone downwards smaller beaker
actually tried this one twice, with cooling aswell..
saltwater apparently went through +10 layers of aluminium foil and made me believe i had distilled some HNO3..
2. 250 mL flask > PTFE hose fitted with aluminium foil into 250 mL flask in cold salt water
on the first i was told the pressure is too high to distill off hno3 with
on the second the gasses seems to be leaking out tho i cant see any NH4NO3 forming when i blow ammonia onto it and i cant smell anything at all;
partial decomposition to NO2
i guess theres still a loss, making the pressure drop and not making the gas go through the PTFE hose
aluminium tube works pretty well also as HNO3 cant really etch aluminium
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chemcam
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Mood: I will be gone until mid-september, on a work contract.
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Is the entire apparatus air tight? If that is the case put a vent at the collection flask side, that will prevent too much pressure and allow gas to
go through makeshift condenser. If it is totally air tight only some gasses will form, compressing the air inside, depending on the amount of heat
going into the acid mix more gas may force its way pressurizing the apparatus until catastrophic failure.
Now that I re-read the post... What temperature are you bringing the acid mix to? I have distilled HNO3 many times and never had a problem. I always
used an oil bath. And I never ever did it totally air tight, maybe under vacuum but never sealed up.
[Edited on 4-20-2013 by chemcam]
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Fantasma4500
International Hazard
Posts: 1681
Registered: 12-12-2012
Location: Dysrope (aka europe)
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Mood: dangerously practical
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Quote: Originally posted by chemcam  | Is the entire apparatus air tight? If that is the case put a vent at the collection flask side, that will prevent too much pressure and allow gas to
go through makeshift condenser. If it is totally air tight only some gasses will form, compressing the air inside, depending on the amount of heat
going into the acid mix more gas may force its way pressurizing the apparatus until catastrophic failure.
Now that I re-read the post... What temperature are you bringing the acid mix to? I have distilled HNO3 many times and never had a problem. I always
used an oil bath. And I never ever did it totally air tight, maybe under vacuum but never sealed up.
[Edited on 4-20-2013 by chemcam] |
what temperature?
well 0.5 on stove
apparently it can go past 110*C if its left for long time enough to my surprise, due to slight NO2 formation
i dont have such fancy setup, nothing to hold hoses etc.
so oilbath could become abit tricky, and it wouldnt matter anyways as my sealing would be really bad anyways
apparently some HNO3 of high conc. was stuck in the hose when i took it apart later on, fuming aggressively
my setups was 250 mL flask to 9mm ID PTFE hose going into 250 mL collection flask, so it wasnt airtight, there was a exit to the flask
but why did it decide to go out through a tiny tiny leak instead of a 9mm tube??
the tubing i was using was 1 metre long and it went straight up for about 15 cm above flask then bending slowly into collection flask, which was in
saltwater bath
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