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Topic: what is the possible error of measuring melting point  (Read 5780 times)

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Offline bluetry

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what is the possible error of measuring melting point
« on: October 04, 2008, 04:34:10 AM »
i have measured the melting point og 2,4-dinitrophenylhydrozone.
the measured mp is higher than the the one given in the data bok
what is the possible error?
thank you

Offline nielsgeode

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Re: what is the possible error of measuring melting point
« Reply #1 on: October 04, 2008, 05:41:18 AM »
i have measured the melting point og 2,4-dinitrophenylhydrozone.
the measured mp is higher than the the one given in the data bok
what is the possible error?
thank you

Are you sure your compound is pure? It helps if you heat up very sloooooooooowly when you are 5-10 degrees celcius lower than your measured mp

Offline T-rex

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Re: what is the possible error of measuring melting point
« Reply #2 on: October 04, 2008, 08:39:42 PM »
If this is for lab in particular, you might want to right down the melting RANGE.

Normally in lab you don't take the melting point. If you use a meltemp type apparatus then it would be optimal to write down the initial temperature the lattice starts to break down, and then the final temperature when the compound has finally melted.

Then the literature melting point should be within the range you have made up.

And at least in my experiences, if the compound you made is impure that means the latticework is interrupted and the melting point would actually be lower than literature. So if it really is legitimately higher, you might have another compound in there from a side reaction.

(Don't put it past machines to be crappy at measuring stuff either.)

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