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Topic: Why some materials decompose before melting?  (Read 3024 times)

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Offline zarabat

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Why some materials decompose before melting?
« on: April 30, 2013, 07:53:35 AM »
I wonder why some materials like some of inorganic ones decompose before melting?

Offline opsomath

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Re: Why some materials decompose before melting?
« Reply #1 on: April 30, 2013, 11:38:01 AM »
There's nothing magic going on, it's just that some compounds have a decomposition temperature that's pretty low.

Offline Arkcon

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Re: Why some materials decompose before melting?
« Reply #2 on: April 30, 2013, 12:44:36 PM »
I suppose there is an answer to this question, but I'm betting its not at all simple.  You've got to figure the relative strengths of intermolecular binding energy (for say, melting) and the forced holding atoms together (for decomposition.)  With some examples, maybe you could begin to figure it out.  But its probably way more complicated than that for many compounds, considering that some atom may help the molecule decompose, by withdrawing electrons from another part of the molecule.  Or intermolecular interactions, one part of the molecule attacking itself, or part of another same molecule.  Probably, if you want to simplify the thought process, you might want to limit yourself to inorganic compounds.
Hey, I'm not judging.  I just like to shoot straight.  I'm a man of science.

Offline Corribus

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Re: Why some materials decompose before melting?
« Reply #3 on: April 30, 2013, 04:45:26 PM »
You've got to figure the relative strengths of intermolecular binding energy (for say, melting) and the forced holding atoms together (for decomposition.) 
And the associated changes in entropy...  :)
What men are poets who can speak of Jupiter if he were like a man, but if he is an immense spinning sphere of methane and ammonia must be silent?  - Richard P. Feynman

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