Sciencemadness Discussion Board

Using a retort

Dream of the iris - 17-2-2006 at 18:30

Anyone have any expirence with using a retort? Any advice on using it to distill HNO3?


MadHatter - 17-2-2006 at 21:15

Distill slowly as the arm off the retort is air-cooled. Make sure you have plenty of
ventilation. It's possible to get 68 to 70% HNO3 provided the H2SO4 is highly
concentrated. You might want to use some boiling stones.

Dream of the iris - 17-2-2006 at 21:58

Ok. Is it possible to obtain higher concentrations with a retort, for example, 90%+?


MadHatter - 18-2-2006 at 10:58

No. For that, vacuum distillation is required at much lower temperatures because the
acid produced in a retort tends to decompose because of the higher temperatures involved.

Dream of the iris - 18-2-2006 at 12:32

What if the tube was cooled? Meaning wrap tubing filled with cold water across it while it's distilling.

mantis - 18-2-2006 at 15:50

You need not to cool. the air will do this job for you.

Liquid cooling

MadHatter - 18-2-2006 at 20:41

You could distill faster but the temperature of the mixture inside the retort will still
decompose some of the acid. Nitric acid gets discoloured by the decomposed oxides of
nitrogen remaining in it.

neutrino - 18-2-2006 at 20:51

>99% Nitric acid is produced by distilling a mixture of a dry nitrate and concentrated sulfuric acid in a vacuum. At a sufficient vacuum the acid will boil cool enough to prevent virtually all decomposition.

The general thinking on these forums is that a vacuum must be used to get any concentration high enough for use in nitrations. Recently, though, this was disputed. Someone (Rosco?) pointed out that atmospheric distillation produces very concentrated acid with minimal decomposition, as long as UV light is excluded. If you want >90% acid, atmospheric distillation will easilly suffice.

If you want to use a retort, I would advise a few things. First, shield your acids from the air. You want to exclude as much water as you can from your acids. Second, do this out of the sun’s rays. UV light decomposes nitric acid into water, oxygen, and nitric oxide(s).

Dream of the iris - 18-2-2006 at 21:12

Something is bothering me about the vaccum distillation.

Brainfevert successfully distilled 90% HNO3 without the use of a vaccum. He didn't even use a retort, he used two jars and some saran wrap (with ice). So, this leads me to believe that it's possible to distill 90% HNO3 without a vaccum, or maybe I just don't want to spend anymore money on distilling equipment.


MadHatter - 19-2-2006 at 09:03

I've seen BrainFever's method for making white nitric. It works because the the mixture
is kept below the decomposition point. This is good for very small amounts of HNO3. I have
to hand it to BrainFever for coming up with this method, however the process is extremely
slow. It took many hours to produce a few milliliters of acid, but if this is all you need then go
for it. My needs are greater, so I'll stick to vacuum distillation for 99% acid.

If, as Neutrino has stated, that it's possible to do this by excluding UV and using anhydrous
ingredients, by all means try it and let us know how it went. I'd still keep the temperature
in the retort down by using a hot water bath around it. The lower the temperature, the better.
If your acid comes out red or yellow, some decomposition has taken place.

[Edited on 19-2-2006 by MadHatter]

Swany - 19-2-2006 at 17:07

I had a brainfever setup, it was like my pet/child. Every morning I would 'feed' it NH4NO3 and H2SO4, scoop the undistilled sludge out, and relieve it of its precious mls of 96% HNO3.

But then, one tragic evening...

..I sold my soul and bought a distillation setup. :P

Darkblade48 - 19-2-2006 at 21:09

Originally posted by Swany
..I sold my soul and bought a distillation setup. :P

That's the equivalent of shooting Old Yeller :o

I should break down and buy myself a 24/40 distillation setup one day...

Flip - 5-3-2006 at 09:51

Using a retort:

"I know you are, but what am I?" :P