Sciencemadness Discussion Board

A question i always wonder about, about removing water from a substance.

KonkreteRocketry - 4-1-2013 at 12:18

I know u can easily force something like dextrose monohydrate's water molecules out by heating it for few hours.

but calcium nitrate mostly exist in tetrahydrate Ca(NO3)2 (H2O)4 form, with a so how to take the water molecules out if this thing already have a melting point under boiling point of water ? but boiling point over water's boiling point, so can i still make it anhydrate ? and any ways i can completely separate water from Ca(NO3)2 ?

AJKOER - 4-1-2013 at 15:02

This may help. Per Wikipedia ( ):

"Anhydrous metal chlorides may be obtained from hydrated metal chlorides by refluxing in freshly distilled thionyl chloride:[14]

MCln·xH2O + x SOCl2 → MCln + x SO2 + 2x HCl "

which is one expensive path if heating is not an option.

Also, depending on the particular compound in question, there may be an anhydrous synthesis, but still compare the relative cost/ease of the thionyl chloride method.

[Edited on 4-1-2013 by AJKOER]

AndersHoveland - 5-1-2013 at 00:07

I have a related question I have always been wondering about. I know that ethyl ether can be dehydrated with conc. sulfuric acid to ethylene gas. Can methyl ether be dehydrated with sulfuric acid ?? If so, what forms?

ThatchemistKid - 5-1-2013 at 20:05

...Ethanol is dehydrated to ethylene by heating in sulfuric acid, via E1 mechanism? Probably with some sort of significant E2 character.

In other words the ether is not dehyrdated, but the alcohol is. Dehydrating methanol doesn't occur as you would just be generating a methyl cation...