Sciencemadness Discussion Board

Water removal with Mg(ClO4)2?

Magius - 20-8-2005 at 20:50

Reading in Waltons Inorganic Preprations, It has the vapor pressure of water above Mg(ClO4)2 as 5x10^-4. To me, this seems awefully low, surpassed(as far as I know) by P2O5.
With the ability to suck so much water from the air so powerfully, would it be possible to use this salt to concentrate dilute solutions of chemicals such asH2O2, H2SO4, Acetic Acid and more?

Just thinking.
It seems to easy though.


E.b.Chemoleo:Title

[Edited on 22-8-2005 by chemoleo]

neutrino - 20-8-2005 at 21:26

If the chemicals don't react with the perchlorate and can be separated afterward, yes. Keep in mind that perchlorates aren't always stable, though.

praseodym - 21-8-2005 at 04:22

Magnesium perchlorate is a powerful oxidiser that reacts with many substances and hence is unstable. Do take note of what you are concentrating as the reaction may get violent as well as explosive.

Magius - 21-8-2005 at 14:52

My intent was not to mix anything with the magnesium perchlorate, but rather place the two in a dessicator in their own dishes. My question is then, could the Perchlorate then "suck" the water out of the other substance that has high vapor pressure of water?

chemoleo - 21-8-2005 at 16:07

Yes, this would work, but once again, i.e. if you use organic substances, they would evaporate themselves. Give this some acid traces, and you may well have HClO4 with organic vapour.... but you have to be very unlucky to screw this one up.

However, things are often dried over P2O5, or conc H2SO4, CaCl2, whatever.

BromicAcid - 21-8-2005 at 17:21

I've read that magnesium perchlorate is on par with phosphorus pentoxide for overall desicating power, but of course magnesium perchlorate should be used very cautiously for drying anything organic, I believe there are accounts of using magnesium perchlorate to dry gasses containing ethanol vapor and later exploding:

After a few minutes of looking...

From http://www.auburn.edu/administration/safety/crcperchloric.ht...
Quote:
Several cases are on record in which magnesium Perchlorate (anhydrone) has exploded while being used as a desiccant (Appendix 1). Smith 6 regards the use of magnesium perchlorate for the drying of alcohol vapors as permissible, but Burton and Praill' warn that if magnesium perchlorate is to be used for drying organic liquids, the purity of the drying agent should be determined since the preparation may have left traces of free perchloric acid in the salt. Explosions involving magnesium Perchlorate may have been caused by the formation of perchloric esters in the system. It should be noted that methyl and ethyl perchlorate are violently explosive compounds.


Edit: And also from sciencemadness in the perchloric acid thread Psycho gives a list of dangers of working with magnesium perchlorate, one example being:
Quote:
3 . A worker using magnesium Perchlorate to dry argon reported an explosion andwarned that warming and
contact with oxidizable substances should be avoided.

4. An explosion was reported when anhydrous magnesium Perchlorate used indrying unsaturated hydrocarbons was
heated to 220'C.


[Edited on 8/22/2005 by BromicAcid]