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Topic: Separating Dry Mixtures  (Read 8832 times)

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Offline weird.science

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Separating Dry Mixtures
« on: September 27, 2006, 10:11:08 PM »
For my chem. class, we are required to separate a mixture of salt, sand, iron, and sugar.  I've already extracted the iron using a magnet, but i need help with extracting the sugar.  The sugar crystals are blue (some detailed info.).  I tried heating them at various temps. and then sifting them, but that didn't seem to work, and i also tried using tweezers (forceps), but that is obviously too lengthy and tedious.

Help?

Any help would be greatly appreciated! ^-^
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Offline mike

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Re: Separating Dry Mixtures
« Reply #1 on: September 27, 2006, 11:05:33 PM »
Blue sugar?

My suggestions:

sieve (although you have already tried this) if the crystals are significantly different.
Dissolve them in water and then recrystalise

As they are different colours I would suggest that you are supposed to separate sugar and salt crystals physically with tweezers.

Here is a similar discussion http://www.chemicalforums.com/index.php?topic=10463.0
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Offline Donaldson Tan

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Re: Separating Dry Mixtures
« Reply #2 on: September 28, 2006, 09:11:26 AM »
Can you identify the salt and the sugar?

I think the sugar might be soluble in organic solvent, but not the salt.
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Offline AWK

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Re: Separating Dry Mixtures
« Reply #3 on: September 28, 2006, 09:21:33 AM »
Quote from: weird.science on September 27, 2006, 10:11:08 PM
For my chem. class, we are required to separate a mixture of salt, sand, iron, and sugar.  I've already extracted the iron using a magnet, but i need help with extracting the sugar.  The sugar crystals are blue (some detailed info.).  I tried heating them at various temps. and then sifting them, but that didn't seem to work, and i also tried using tweezers (forceps), but that is obviously too lengthy and tedious.

Help?

Any help would be greatly appreciated! ^-^
None sugar is blue. Your mixture probably contains copper sulfate..
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Offline weird.science

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Re: Separating Dry Mixtures
« Reply #4 on: September 28, 2006, 09:43:46 AM »
they are blue sugar crystals ( as used for decorating cookies)
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Offline weird.science

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Re: Separating Dry Mixtures
« Reply #5 on: September 28, 2006, 09:53:10 AM »
A little more info on the salt, sand, iron filings, and blue sugar crystals mixture that needs to be separated.  I extracted the iron filings with a magnet.  I thought the sand and the salt could be added to water, the sand would settle to bottom, filter that out, and then boil the water to leave salt residue, but I can't figure out how to extract the blue sugar crystals.  I found out that sugar has a lower melting point than salt and sand.  I thought by heating the dry materials the sugar would melt before the other two, but it just burned the sugar and clung to the salt and sand.  I don.t know what to do from here.

Thanks for any *delete me*
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Offline Donaldson Tan

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Re: Separating Dry Mixtures
« Reply #6 on: September 28, 2006, 11:17:03 AM »
Quote from: weird.science on September 28, 2006, 09:53:10 AM
I found out that sugar has a lower melting point than salt and sand. 

Does this sugar undergo thermal decomposition?
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"Say you're in a [chemical] plant and there's a snake on the floor. What are you going to do? Call a consultant? Get a meeting together to talk about which color is the snake? Employees should do one thing: walk over there and you step on the friggin� snake." - Jean-Pierre Garnier, CEO of Glaxosmithkline, June 2006

Offline weird.science

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Re: Separating Dry Mixtures
« Reply #7 on: September 28, 2006, 12:31:45 PM »
no it does not
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Offline mike

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Re: Separating Dry Mixtures
« Reply #8 on: September 28, 2006, 08:58:29 PM »
Separate them with tweezers and a magnifying glass.
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Offline weird.science

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Re: Separating Dry Mixtures
« Reply #9 on: September 29, 2006, 12:27:59 PM »
That's what I ended up doing.  It took 5 hours!
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