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Topic: Melting point determination  (Read 7818 times)

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Offline glaizy

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Melting point determination
« on: July 04, 2011, 12:52:35 PM »
Why should you always use a new capillary tube with a sample of your compound
when doing a second melting point determination? 

i have searched a lot about this in the internet but i ended up nothing...

 ???

Offline discodermolide

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Re: Melting point determination
« Reply #1 on: July 04, 2011, 01:02:29 PM »
Why should you always use a new capillary tube with a sample of your compound
when doing a second melting point determination? 

i have searched a lot about this in the internet but i ended up nothing...

 ???

Because you may have generated a new crystal modification, which has a different MPt.
Or the compound may have decomposed.
Capillary tubes are not expensive
Development Chemists do it on Scale, Research Chemists just do it!
My Research History

Offline glaizy

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Re: Melting point determination
« Reply #2 on: July 04, 2011, 01:08:59 PM »
Why should you always use a new capillary tube with a sample of your compound
when doing a second melting point determination?  

i have searched a lot about this in the internet but i ended up nothing...

 ???

Because you may have generated a new crystal modification, which has a different MPt.
Or the compound may have decomposed.
Capillary tubes are not expensive



THANK YOU SO MUCH!i have some other question regarding melting points..

which has a wider melting range , a mixture or a pure substance?

Offline discodermolide

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Re: Melting point determination
« Reply #3 on: July 04, 2011, 01:21:53 PM »
Why should you always use a new capillary tube with a sample of your compound
when doing a second melting point determination?  

i have searched a lot about this in the internet but i ended up nothing...

 ???

Because you may have generated a new crystal modification, which has a different MPt.
Or the compound may have decomposed.
Capillary tubes are not expensive



THANK YOU SO MUCH!i have some other question regarding melting points..

which has a wider melting range , a mixture or a pure substance?

A mixture
Development Chemists do it on Scale, Research Chemists just do it!
My Research History

Offline glaizy

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Re: Melting point determination
« Reply #4 on: July 04, 2011, 01:49:32 PM »
Why should you always use a new capillary tube with a sample of your compound
when doing a second melting point determination?  

i have searched a lot about this in the internet but i ended up nothing...

 ???

what is the effect of the impurity of the boiling point of a substance?

some of my sources said that i will increase and some told me that it will decrease...

 ???

Because you may have generated a new crystal modification, which has a different MPt.
Or the compound may have decomposed.
Capillary tubes are not expensive



THANK YOU SO MUCH!i have some other question regarding melting points..

which has a wider melting range , a mixture or a pure substance?

A mixture

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