yellow nitric acid

[Geo]

im just finishing a quart of nitric acid from my still and the acid is yellow from NO2. if i cap it now, will it build pressure or should i wait until it clears to cap it. i actually cut the temperature in half of what i normally run it at and i still got alot of NOx formed. i used calcium ammonium nitrate and concentrated sulfuric without the water. the acid was concentrated from the very first drop. i have no doubt its better than isotropic. thats why it is fuming. it looks like its steaming but the jar is cool to the touch. i am considering leaving it sit open until the color clears before putting the top on. i have in mind to fill a 1 gallon amber jug i have before using any to get an idea how far 1 gallon will go. ive always made it by the batch as i needed it.

 

[mjgraham]

I use the same method and I get some yellow acid to. I tested it and it was like 52% so I decided to evaproate it to around 68% I figured how much water I needed to evap. and heated it to like 90C for a while. Tested it after and it was 64% but it was like you said fumed in the air when it was cold, as for if you question I don't know . I have tried low heat, high heat get about the same either way, after a day or two it clears but as for pressure don't know.

 

[butcher]

Add a little concentrated 30%H2O2, or a few prills of urea.

 

[Geo]

thanks guys. i feel it was too hot starting out and i had alot of decomposition.

Butcher, thanks, but i dont have either of those right now. i have never used urea to neutralize nitric acid and the H2O2 is out of my reach at the moment. i may be able to get some tomorrow at a hair salon. i could leave it open until then.

 

[butcher]

If it is cool and dark it should not hurt to cap it, the nitric is decomposing to HNO2 NO2 in solution, uncapped it will continue to vapor off decompose until it azeotropes, capped the pressure will build some in the bottle but should also help to keep the nitric from decomposing off further.

kind of like a steam boiler (or pressure cooker) where pressure keeps water from boiling at a higher temperature, the pressure keeps the vapors from forming, allowing the water to become a higher temperature without boiling.

I would losen the cap once in a while to relieve a little pressure, storing in as cool of a dark place as safely possible.

The urea will dot destroy the nitric acid but will help to rid it of the decomposed NO2 gas or HNO2.
Where the concentrated hydrogen peroxide can help to convert NO2 to HNO3.
Dilute peroxide would work also or even dilutiong the acid plain water will help, but these will also dilute your nitric acid.

 

[Pantherlikher]

To be safe since unsure, cap it but put it inside a bucket and cover with a rag. In the event the unwanted happens, you wouldn't want fragments with acid flying, or the mess.
BS.
Too many messes in my days...