Sciencemadness Discussion Board

dehidratant agent

menchaca - 28-9-2003 at 05:22

what temperature would i need to get anhidrous Na2SO4 from Na2SO4.10H2O?

thanks!!

BromicAcid - 28-9-2003 at 05:58

According to Hawley's Condensed Chemical Dictionary "mp 33 C (liquefies). Loses water of hydration at 100 C" So if you keep beating on it with heat it will stay at about 100 C until it looses its' water of hydration and when it starts to rise there it will be the anhydrous solid with the mp of 888C.

menchaca - 28-9-2003 at 06:01

ok thanks a lot!!! i wanted it for using as dehidratant agent to get >95%HNO3 from HNO3 68%:D

vulture - 28-9-2003 at 12:24

I'm not sure if that'll work. If it would, the industry would be using it in huge amounts, since it's dirt cheap.

The main problem is that SO4 2- is basic enough to get protonated by HNO3. You'll get strange compounds in your reaction, something like NO3.HSO4 I guess.

menchaca - 1-10-2003 at 02:44

then what can i do? i have no acces to a source of concentred sulfuric acid what other konds of dehidratant agents can i use?

JustMe - 1-10-2003 at 14:30

I don't have my books with me now, and I've done a little googling. Yep, you need concentrated sulfuric acid, allright.

However, if memory serves me correctly, phosphorus pentoxide ought to do it too. It's such a powerful dehydrating agent that it'll dehydrate concentrated HNO3 to N2O5. So I would guess that it would pull most of the water out from less concentrated nitric acid to form phosphoric acid, which has a much higher boiling point than the nitric. Anyway, this is just a presumption... never done this.

[Edited on 1-10-2003 by JustMe]

Gotta remember to spell. (edits)

[Edited on 1-10-2003 by JustMe]