Sciencemadness Discussion Board - Concentrating Nitric Acid?

Concentrating Nitric Acid?

Chemist514 - 2-7-2006 at 09:24

I see many threads on making it, but not much on concentrating some you already have, I can get alot of 15% nitric acid for a reasonable price it would be nice if there is a "simple" process to remove some water from it.
(I know that this is VERY hard with acetic and sulfuric..)
anyone able to point me to a thread?

hinz - 2-7-2006 at 10:20

Concentrating 15% nitric is hard. If you want some concentrated, just add some nitrate to H2SO4 ( suppose you know

). If you have only this acid I would first destill of some water, till it's around 50%(68% is azeotrophic but hard to make without dehydrating agent) and then destill the conc. acid with H2SO4 as dehydrating acid. If you have enough sulfuric, you can first form some nitrate salt with the nitric (K, Na, Ca, maybe NH4+) dry this and then do the classic sulfuric method.

[Edited on 2-7-2006 by hinz]

The_Davster - 2-7-2006 at 10:32

In my opinion, the ammount of sulfuric needed for the concentration of dilute acid, even 50% is way too much. I would just neutralize with K2CO3, isolate KNO3, and distill that with slightly diluted sulfuric to get the azeotropic 70% acid.
https://sciencemadness.org/talk/viewthread.php?tid=1851
Stuff relavent to this topic comes later in the first page.

dejitaru - 2-7-2006 at 22:07

How would you concentrate 75% nitric to 90%?

Maja - 3-7-2006 at 01:35

With good dehydrating agent, like H2SO4.

Acid drain opener drying agent...

Chemist514 - 8-7-2006 at 06:11

Would Clear-Line or Liquid Fire H2SO4 based drain openers work here?

neutrino - 8-7-2006 at 06:17

I don't see why not. Sulfuric acid is sulfuric acid and as long as it doesn't have water in it, it will dehydrate.

dejitaru - 7-8-2006 at 10:47

Quote:

Originally posted by Maja
With good dehydrating agent, like H2SO4.

How do you do that?

Maja - 7-8-2006 at 10:52

Just mix it by volume 1/1 and distill at low temperature to avoid HNO3 decomposing.

Vacuum Distillation

MadHatter - 7-8-2006 at 12:26

You can vacuum distill the 15% acid at low temperature to get the fuming white version.
That's generally at least 90% HNO3. If the acid is yellow or red than some decomposition
has occurred during distillation. The usual reason is that the distillation temperature is too
high.

dejitaru - 7-8-2006 at 19:48

Is there a site with instructions on how to do that?

neutrino - 8-8-2006 at 08:06

Not really. The forums (this one and roguesci.org) are the best resource.

ac- - 3-7-2007 at 05:43

Hmm.. Just found a good source for 10l 30% nitric acid with about 2-4% phosphoric acid in it, but anyway is it relatively easy to distill a little bit of water out of this to get, lets say 50% nitric acid?

I dont have any proper distilling apparatus and im low on sulfuric acid too

not_important - 3-7-2007 at 06:38

You need reasonably good apparatus to concentrate the acid. The constant boiling acid, at standard pressure, boils at 120.5 C. That's close enough to water that you need some fractionating capability, or you will need to to a great many distillations and redistillations to get to the more concentrated acid.

You also need all glass apparatus, or take a good deal of care in assembling it otherwise. Rubber stoppers don't like HNO3 vapours, before glass joints were around they'd use corks soaked in waterglass to somewhat acid-proof them.

But you can get nitric acid concentrated to the 65 to 60 percent range without H2SO4, with just distillation.

Extraction with a chlorinated solvent seems to be another choice, I think there's specifics on various thread on the board. Partition the acid between the water in it and the solvent, separate the solvent and distill it away from the HNO3.

I don't have the water-HNO3 freezing point curves, but it might be possible to concentrate the acid by freezing. However this means the ability to slowly lower the temperature over a period of time, not just stick a bottle of the acid in the fridge.

tito-o-mac - 3-7-2007 at 07:29

Use a fume carboard(if you have one) to ensure that you do not breathe in any of these red fumes

greenyppols - 24-7-2007 at 08:44

I was going to concentrate 70% HNO3 by adding DCM, separating it and distilling off the DCM to leave the Nitric acid behind. I checked the MSDS of DCM and noticed its not compatible with Nitric?? Huh??
Prior to this,I had made Nitric using Method #2 in King's Chemistry book, which used DCM extraction. Method #3, which I was going to try 99% HNO3, which also uses DCM extraction to concentrate the Nitric...so Im a bit confused and hoping someone here can explain? Am I missing something here? I feel comfortable going ahead as planned but am stilling curious...

Im thinking maybe its not compatible when its already a high concentration of Nitric (like adding DCM to White/Red Fuming? Or what conditions is DCM not compatible. It must say that on the MSDS for SOME reason and Im hoping to receive some enlightenment.

Aqua_Fortis_100% - 30-7-2007 at 11:38

Quote:

<i>Originaly posted by greenyppols:</i>
Prior to this,I had made Nitric using Method #2 in King's Chemistry book, which used DCM extraction.

Can you give more info about this book?? I know which there are many threads about the subject , but a book is a very nice source to get additional info.
Thanks.

[Edited on 30-7-2007 by Aqua_Fortis_100%]