I did a search but I couldn't find an answer to my question (Or I did a BAD search ?...)

so, when you distill your mixture of sodium nitrate and sulfuric acid, could the speed of the distiilation be increased with a vacuum pump ? Or will I only get a "more pure" product witout too much NOx ?

thanx ! (and sorry if this topic have been discuted in the past...)

I'm not shure but I think you get more NO2 dissolved in the HNO3 with a vacum. The HNO3 itself will be purer. The NO2 is easily removed ny adding urea to the acid.

I will get more NO2 in my acid ?! I though no...
but, like you said : it's easy to purify acid with urea. But what about the speed of the distillation ?

see ya !

So for things like RDX that call for non fuming nitric acid, you can just add a little urea to make it clear and non fuming?! cool, but how much urea do I add, per say 100ml?

<small>[ April 06, 2002, 06:50 AM: Message edited by: The Great Milenko ]</small>

Using a vaccuum pump will reduce the amount of NO2 in the acid because the low pressure reduces the boiling point of the acid, so it doesn't get as hot before it distils over, so there is less thermal decomposition. Decomposition is very undesirable because it produces both H2O and NO2.
Reducing the pressure will tend to make the acid distil over more quickly, but it will depend on how hard you heat it.

"So for things like RDX that call for non fuming nitric acid"... RDX needs 95% HNO3 or better for decent yields. Trust me, it fumes. A lot.