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Topic: Energy question  (Read 1914 times)

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Offline sn1sn2e1e2

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Energy question
« on: March 23, 2014, 11:37:04 PM »
What is the relationship among the magnitudes of enthalpies of combustion, fusion, and vaporization for hexane?

 Vaporization obviously is greater than fusion since it takes a lot more energy to spread molecules apart. I chose "fus< vap < combust" (which is right) but I am not sure why heat of combustion is greater than vaporization.

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Offline Borek

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Re: Energy question
« Reply #1 on: March 24, 2014, 03:52:15 AM »
What bonds are broken/created during melting/evaporation?

What bonds are broken/created during combustion?

How do energies of these bonds compare?
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Offline sn1sn2e1e2

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Re: Energy question
« Reply #2 on: March 24, 2014, 09:29:02 PM »
OH!

In combustion, the chemical bonds (intra) are BROKEN which are obviously stronger (like 1000 times) than intermolecular forces.

In fus and vap, only intermolecular forces are "involved".

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