barbs09
Hazard to Others
Posts: 113
Registered: 22-1-2009
Location: Australia
Member Is Offline
Mood: No Mood
|
|
Isolating a deliquescent crystals from a saturated solution
Hi, I was hoping someone can either point me to a good review or supply a few pointers on obtaining crystals from a deliquescent salt solution. I
have searched the "F£$king search engine" with mixed results. I have a solution of Lithium Bromide which I have in a wide mouthed porcelain
evaporating bowl over a heater. It has reduced significantly in volume and on cooling does crystallise to a greasy wet mass. At this stage, if I
transferred it to a closed container with a good surface area of say anhydrous Magnesium sulphate or copper sulphate, could I potentially get it to
the stage of being a bottleable reagent? many thanks, AB
|
|
|
Bedlasky
International Hazard
Posts: 1239
Registered: 15-4-2019
Location: Period 5, group 6
Member Is Offline
Mood: Volatile
|
|
I think yes, I have once solution of very very soluble salt, which refused to crystallize, so I must put the beaker to the plastic bag with CaCl2 to
obtain crystals.
You can try to dry your LiBr in owen. This should also work.
|
|
|
Oxy
Hazard to Others
Posts: 140
Registered: 1-12-2020
Member Is Offline
|
|
You can easily remove the water by applying heat and vacuum. RBF with gas take-off adapter connected to vacuum pump or water aspirator and placed in
heating mantle will be more than enough.
I used that for drying CuBr2 from wet, watery mass to crystals.
|
|
|
macckone
Dispenser of practical lab wisdom
Posts: 2168
Registered: 1-3-2013
Location: Over a mile high
Member Is Offline
Mood: Electrical
|
|
recrystalizing from isopropanol is going to work better.
n-propanol works best but is not as easily available.
take your hot saturated solution of LiBr in a liquid state and dump in isopropanol.
you should get an immediate precipitate of LiBr crashing out.
you can then take your solution and repeat the process of boiling it down to concentrated (possibly reclaiming the isopropanol) and repeat.
isopropanol has a 2:1 solubility coefficient between boiling and 0C.
Recrystallizing from dry isopropanol should yield nice crystals.
If you just want dry crystals (anhydrous), you are going to have to use a vacuum dessicator of some kind with heat.
Oxy's suggestion of a rbf with vacuum take off is a good one.
Solubility of LiBr in alcohols:
https://doi.org/10.1016/j.fluid.2011.03.017
|
|
|
WGTR
National Hazard
Posts: 971
Registered: 29-9-2013
Location: Online
Member Is Offline
Mood: Outline
|
|
One ancillary tip is to crystalize the salt on some Teflon film (or plastic bag) fitted inside of a crystalizing dish. That way you don't have to
scrape the dry salt off the glass.
It seems that wet LiCl decomposes a bit under heating. Isn't it normally dried under flowing dry HCl? I suppose LiBr is more resistant to this type
of decomposition.
|
|
|
barbs09
Hazard to Others
Posts: 113
Registered: 22-1-2009
Location: Australia
Member Is Offline
Mood: No Mood
|
|
Thanks, heaps to work with here.
Cheers
|
|
|
![[*]](images/xpblue/default_icon.gif){kind=icon}
