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Topic: Melting points...  (Read 3582 times)

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Offline select87

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Melting points...
« on: January 21, 2008, 05:06:04 AM »
Ok,
1 mixture: 2 substances, 1 container.

Substance#1 melts at a (slightly) higher temp than Substance#2.

How would one remove all of Substance#1 while losing a minimal amount of substance#2?

a) heat mixture at low temp for long intervals, several times
b) heat mixture at low temp for short intervals, several times
c) heat mixture at low temp for a very long time, just once
d) heat mixture at high temp for short intervals, several times
e) heat mixture at high temp for a long time, just once
f) heat mixture at extreme high temp, for a short time, just once

Or other suggestion _________________ .

Hope this makes sense. Its to help me study for a chemistry exam. (Yes, I'm 20 and still in high school.. lol) please help..

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Re: Melting points...
« Reply #1 on: January 21, 2008, 05:16:18 AM »
Something is wrong - either the question, or the way you quote it. Just heating mixture will not remove the substance.

Besides, it doesn't make sense for other reasons too. Looks to me like many assumptions were made but not listed explicitly.
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Offline select87

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Re: Melting points...
« Reply #2 on: January 21, 2008, 05:31:26 AM »
once melted and continually heated heated they turn to gas and burn up. trying to burn off all of the chemical with the higher melting point, while leaving the chemical with the lower melting point.

Offline Alpha-Omega

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Re: Melting points...
« Reply #3 on: January 21, 2008, 05:52:48 AM »
PART 1: 

1 mixture: 2 substances, 1 container.

Substance#1 melts at a (slightly) higher temp than Substance#2.

How would one remove all of Substance#1 while losing a minimal amount of substance#2?

a) heat mixture at low temp for long intervals, several times
b) heat mixture at low temp for short intervals, several times
c) heat mixture at low temp for a very long time, just once
d) heat mixture at high temp for short intervals, several times
e) heat mixture at high temp for a long time, just once
f) heat mixture at extreme high temp, for a short time, just once

Or other suggestion _________________ .


Hope this makes sense. Its to help me study for a chemistry exam. (Yes, I'm 20 and still in high school.. lol) please help..

PART 2: 


Once melted and continually heated heated they turn to gas and burn up.
And this part:  trying to burn off all of the chemical with the higher melting point, while leaving the chemical with the lower melting point.

So are you seeking a separation process????  This is/is not a MP experiment? 

Logically, the mixture will have a different MP than either of the two subtances as pure materials..

PART 1:  You are trying to do this separation per MELTING POINT?? Or does
OTHER SUGGESTION MEAN SUGGEST OTHER METHOD???

PART 2:  This once melted and continuous heating statement and they turn to gas...if gas they are in vapor phase...if burn up...they are in state of decomoposition...and they are NOT tansparant to optics in a melting point apparatus with optical path/sensors.

1.  Is this supposed to be done ONLY using Melting Point?
2. What type of MP apparatus?  MP block with oil and thermometer oris this in a state-of-the-art Mettler system with optical sensors/path?

Off the top of my head...I would say try GC....gas chromatography to effect separation of two materials with different BPs...but that does not make sense..if this is HS...and ...mybe distillation...OK need more 411.

OK, if you paraphrased the question can you send it as written...Please help me to understand what it is you are trying to do?  The more details you can give ...then that would be helpful..

This site discusses separation of mixtures.  Maybe it will help you pose the question more clearly:  http://antoine.frostburg.edu/chem/senese/101/matter/separation.shtml
« Last Edit: January 21, 2008, 07:53:49 AM by mebecker1 »

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