Sciencemadness Discussion Board

Failed to stop HNO3 from fuming.

freedompyro - 7-1-2012 at 23:13

I have been quite annoyed at my HNO3 lately. It likes to red fume during a nitration at as low as 11C... :o This didn't use to happen before.

So, In an attempt to remove the fuming I first diluted 118g of my HNO3(Around 93-95%) with 25g water. Still red fuming... Then I added urea prills slowly and they fizzed away. When prill addition caused no more fizzing I let the last tiny pieces of urea dissolve away. Then I got acid that was white fuming. Progress!!! :D But, I wanted it to totally stop fuming... So then I diluted it with 15g more water.

Stuff is still fuming... What gives?!? I thought it stopped fuming at below 70%. Not going to dilute it any more or it's going to be a waste of H2SO4.

Also, what did the urea turn into?

neptunium - 8-1-2012 at 00:38

do you live in a very humide area? the fuming can be caused by a lot of water disolved in the air...

Pulverulescent - 8-1-2012 at 02:30

Quote:
Also, what did the urea turn into?

Nitrous acid, present in nitric acid reacts with urea; 2HNO<sub>2</sub> + NH<sub>2</sub>CONH<sub>2</sub> ---> 2N<sub>2</sub> +CO<sub>2</sub> + 3H<sub>2</sub>O.
Any remaining urea forms urea nitrate!

P

Endimion17 - 8-1-2012 at 03:23

It always fumes excessively during the winter because it's quite humid. Case solved. :P

[Edited on 8-1-2012 by Endimion17]

freedompyro - 8-1-2012 at 03:25

Yea, it's very humid here.
Crap... Now I have trace amounts of urea nitrate in my nitric acid. Oh well... Not really a issue.

Red fumes coming off a nitration even at 5-10C unsettles me and filters don't handle NOX as well. :o Better and safer to use a around 93% WFNA than a 95%+ RFNA for most things.

Btw, what are the white fumes? Are the red ones NO2, and the white ones NO combining with water vapor?

[Edited on 8-1-2012 by freedompyro]

Adas - 8-1-2012 at 03:46

The white fumes is probably HNO3 itself.

Pulverulescent - 8-1-2012 at 04:50

When decolourising RFNA, only very minimal quantities of urea should be added!

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neptunium - 8-1-2012 at 09:54

Quote: Originally posted by Endimion17  
It always fumes excessively during the winter because it's quite humid. Case solved. :P

[Edited on 8-1-2012 by Endimion17]

winter is usualy the driest season (at least up here in the great lakes ) cooler air cant disolve as much water as warmer air .

freedompyro - 8-1-2012 at 13:35

The amount of water vapor the air can hold at a specific temperature != humidity. Humidity is the amount of water vapor in the air in relation to how much it can hold at the current temperature.

Pulverulescent - 8-1-2012 at 13:39

Yeah, it's all about saturation . . .

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Endimion17 - 8-1-2012 at 14:50

Quote: Originally posted by neptunium  
Quote: Originally posted by Endimion17  
It always fumes excessively during the winter because it's quite humid. Case solved. :P

[Edited on 8-1-2012 by Endimion17]

winter is usualy the driest season (at least up here in the great lakes ) cooler air cant disolve as much water as warmer air .


That matters only if he's doing this outside. Inside places without proper heating usually have high relative humidity. I myself have pretty bad problems with it.

...

...

Dang, I forgot to close the waster water tank and now it will evaporate constantly while I'm away. %&$#?@! :mad:

neptunium - 10-1-2012 at 11:51

ha!
yeah i put every fuming acid in the fridge (when in open container for small test ) beacause when you dont ....it wont stop fuming untill the whole room is filled ....and then some!

Hexavalent - 10-1-2012 at 11:56

That's a good idea . . .if only I had a fridge for dedicated lab use:/