Sciencemadness Discussion Board

Separating KCl and NaCl

thalium - 8-1-2005 at 11:31

Do you know how to separate two solids? I need to separate KCl from NaCl. This mixture is like this: KCl 66%, NaCl 33.3% and MgCO3 0.7%

Edited title. chemoleo.

[Edited on 9-1-2005 by chemoleo]

HNO3 - 8-1-2005 at 12:50

I separated crystals of the two by hand. The NaCl will be clear crystals, while the KCl will be "foggy". Other than that, potassium chloride is soluble in alcohol, whereas NaCl isn't.:)

thalium - 8-1-2005 at 13:39

alcohol as in medicinal alcohol? That's the only kind I have right now

HNO3 - 8-1-2005 at 13:52

I think most any alcohol will work, try it.

cyclonite4 - 9-1-2005 at 04:23

Is your mixture "low-sodium" salt. I saw one at the shops and it had the exact same ingredients (although there was less KCl and more MgCO3).

thalium - 9-1-2005 at 06:01

Yes it is and HNO3s' method worked

evilgecko - 9-1-2005 at 11:54

Soluble in alcohol, like meths? Man that would really help. I've been doing it by fractional crystallisation as KCl has a steep solubility curve while NaCls one is basically flat.

[Edited on 9-1-2005 by evilgecko]

thalium - 9-1-2005 at 13:01

this is it:

NaCl_in_alcohol.jpg - 52kB

HNO3 - 11-1-2005 at 19:29

I call the method reverse solvent extraction (RSE). It involves mixing the solution with a water soluble solvent that one off the salts isn't soluble in. If you mixed a solution of the salts that needed separating, the insoluble salt will precipitate. If you place the solid salt in the solvent, the soluble salt will be extracted, leaving the insoluble salt behind. Either way, you can filter the solution to remove the insoluble salt and evaporate the solution to recover the soluble salt.

Thalium: where did the blue color in the solution come from?

jimwig - 12-1-2005 at 14:04

it would see the pyro sites to do with chlorate and or perchlorate production would give some info on this.

also check Merck online for solubility tables or the CRC in your local library.

thalium - 12-1-2005 at 23:41

That alcohol was from a bottle bought from the supermarket and it was for medicinal use. I found another source for NaCl so I don't have to separate anymore.

CRC data

MadHatter - 13-1-2005 at 17:46

FYI, solubilities for KCl and NaCl from CRC 62<sup>ND</sup> Edition 1981-1982:
Solubility is grams per 100 ml H<sub>2</sub>O:

KCl____23.8 @ 20C____56.7 @ 100C
Other solvents: Slightly soluble alcohol; soluble ether, glycerin, alkalai.

NaCl____35.7 @ 0C____39.12 @ 100C
Other solvents: Slightly soluble alcohol, liquid, NH<sub>3</sub>; soluble glycerin;
insoluble HCl

Hope this helps.

thalium - 14-1-2005 at 00:36

I knew those, but maybe others need them.

darkflame89 - 21-1-2005 at 00:51

I would like to ask, when KCl dissolves in alcohol, does it mean that ions are produced in the alcohol. Does KCl dissolved in alcohol conduct electricity?

tom haggen - 21-1-2005 at 12:59

Why exactly is potassium more soluble in alcohol than sodium? When potassium chloride disolves in alcohol you have K+ and Cl- floating around in the solution. Yes this solution would conduct electricity.

[Edited on 21-1-2005 by tom haggen]

KonkreteRocketry - 25-3-2013 at 09:16

Quote: Originally posted by HNO3  
I separated crystals of the two by hand. The NaCl will be clear crystals, while the KCl will be "foggy". Other than that, potassium chloride is soluble in alcohol, whereas NaCl isn't.:)


I have denatured alcohol, do u think that will work ?

ScienceSquirrel - 25-3-2013 at 09:37

Complete solubility data for sodium and potassium chloride from 0 to 100C in water can be found here;

http://en.wikipedia.org/wiki/Solubility_table

nezza - 25-3-2013 at 14:39

The classic method of separating KCl from a mixture with NaCl is based on the fact that the solubility of NaCl dose not change much with temperature so :-
Dissolve the mixture in as little boiling water as possible.
Filter
Cool
Filter off any crystals. These will be Mainly KCl.
Recrystallise these to purify the KCl.
You will be left with a solution saturated with NaCl, but not with KCl
You could add a small amount of the mix to this at room temperature. Some KCl will disssolve but very little NaCl.
Mix for a while and filter. The solid should be mainly NaCl. Wash and dry.

jock88 - 25-3-2013 at 15:20



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