Sciencemadness Discussion Board

distillation setup failure

Ral123 - 25-10-2012 at 05:51

With great success I've been able to distill nitric acid from KNO3/H2SO4 and get nice sulfuric free WFNA. I used old flask, rubber stopper and long and thin aluminium pipe. The rubber stopper kinda pasivates and doesn't get eaten away too readily. Only ignites a little but nothing too serious. This afternoon I decided to do a really heavy duty distill and filled quite a lot of stuff in the flask. I was supposed to get 80ml of WFNA and if it's more it'll surely contain sulfuric. I got my 80ml and decided to continue with another vessel, in case there would be nitric in the sulfuric that is to come. It gave more then 100ml witch was strange, and then I measured density of water.
Here's what it turned out to be...
http://imageshack.us/photo/my-images/109/img1724m.jpg/
I'm not sure why it failed like that, why holes, why it's not evenly eaten away.
Can you give me an advice, will this work if I'm careful not to let H2SO4 vapors in the pipe or is there some other setup that will work well. They sell silicon houses, are they good?

hissingnoise - 25-10-2012 at 06:02

Quote:
Can you give me an advice . . .

Rubber and aluminium are attacked by the corrosive vapours so, yes, get yourself an all-glass still!


Ral123 - 25-10-2012 at 06:14

They use aluminium for IRFNA barrels, they sell wonderful 1L setups for like 100-200$ Mine was 4$ for the flasks and 4$ for the pipe. For the price of the 'nice' kit I can buy 20kilos of pure analitical WFNA. Isn't NG made in steel nitrators?

elementcollector1 - 25-10-2012 at 10:26

I have a rubber thermometer adapter on my distillation set (otherwise glass and Keck clips). Is this prone to being eaten away by bromine and nitric acid / hydrochloric (separately)?

Mailinmypocket - 25-10-2012 at 10:55

Quote: Originally posted by elementcollector1  
I have a rubber thermometer adapter on my distillation set (otherwise glass and Keck clips). Is this prone to being eaten away by bromine and nitric acid / hydrochloric (separately)?


Yes it would at the very least become hardened, and perhaps cracked.

elementcollector1 - 25-10-2012 at 11:08

Darn. Is a thermometer needed to monitor this type of thing?

Mailinmypocket - 25-10-2012 at 11:14

Quote: Originally posted by elementcollector1  
Darn. Is a thermometer needed to monitor this type of thing?


It's better to have it for the HNO3, but not necessary. I have made both many times without a thermometer before I had one, bromine really doesn't need a thermometer at all though.

elementcollector1 - 25-10-2012 at 11:14

Oh. Well, in that case, time to ask my Chem teacher for a good ground-glass stopper for that spot instead.

Mailinmypocket - 25-10-2012 at 13:16

Sorry- didn't notice you mentioned HCl, that should be okay... But definitely not HNO3 or Br2