Sciencemadness Discussion Board

Question about concentrating sulfuric acid

mcduff - 13-10-2005 at 07:56

Ok,

From what I've been reading you have to heat the battery acid up to 250 C +. Why is that?

If battery acid is just water + sulfuric acid, why can't I just boil the water off at 100 degrees celcius until I'm left with sulfuric acid?

The MSDS sheet says that battery acid boils at 110 degrees celcius.

http://www.interstatebatteries.com/www_2001/content/products...

Sorry if its an ignorant question, I just wanna know why. Thanks for any help.

jimwig - 13-10-2005 at 08:28

98 per cent right off the shelf in the plumbing section of most approipriate stores.

fuck battery acid.

higher than that to achieve fuming one must AFAIK add sulfur trioxide - a delicious little demon in and of itself.

BTW what the easiest SO3 production- (just before someone else asks,haha)

"Hey jimwig, UTFSE-nitiwt" - duh I sorry....


To actually get the last of the water out of the sulfuric off the shelf stuff I will search and find it - most likely in "Purification of Chemicals" by Perrin(?).

[Edited on 13-10-2005 by jimwig]

chromium - 13-10-2005 at 09:00

Boiling temperature rises when concentration goes up. 70% sulfuric acid needs 250C or more to give off any water.

By boiling battery acid at normal pressure you can go to 85 ... 90%. You need at least 270C for this and good fume hood because there will be lot of toxic fumes. Only glass or glassed vessels can be used.

Do not try this if you have no experience with boiling and evaportaing less dangerous chemicals.

Nerro - 13-10-2005 at 10:02

the eventual product really will not justify the trouble and the effort that goes into carefully boiling sulfuric acid. Don't forget that boiling hot sulfuric acid may not be something you want to spill over yourself ;)

Just get it in a store. ~96% almost free.

[off topic]
I believe you can make SO3 by adding (HPO3)n to concentrated sulfuric acid. And of course you could make a generator for it with KNO3/S and a V2O5 catalyst.

woelen - 13-10-2005 at 11:48

Quote:
BTW what the easiest SO3 production- (just before someone else asks,haha)

There is a whole thread on that subject. And I can tell you from that thread, that it is not easy at all.

http://www.sciencemadness.org/talk/viewthread.php?tid=727

vulture - 13-10-2005 at 12:36

I think we've been over this before, ad nauseam.

Furthermore, if you do not know why it is you need to concentrate sulfuric acid in this way, you should stay well away from it. It shows a pertinent and dangerous lack of knowledge.

I bet you were going to boil it down in a metal container or some pickle jar.