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Name: Jocelyn T.
Status: student
Age: 15
Location: N/A
Country: N/A
Date: 2001 - 2002


Question:
Recently, I have been taught a lesson on purification and I was curious on how can we separate salt from sugar as we know that both salt and sugar a soluble in water? Is the any special methods in separating salt and sugar when they are mixed together?


Replies:
There are a lot of ways to do this separation. Why not try a selective precipitation. I am not sure the specific one I will suggest will work, but it will give you an idea of how to approach the problem.

1. Evaporate as much of the water as you can without precipitating one or the other compounds.

2. Slowly add a volatile organic solvent. A reasonable one might be acetone, but ethyl alcohol, or isopropanol may also do. The salt should be much less soluble than the sugar in the blended solvent mixture and you may see "clouds" of salt form as you approach the solubility of salt in the mixed solvent.

3. Filter the precipitate.

You may have to repeat steps 1.-3. again. I just do not know the solubility of NaCl in these mixed solvents.

Give it a try. I will try to think of some other approach because these "simple" separations are good training in chemical lab techniques.

Vince Calder



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