acetylmandarin

2+ Year Member
Oct 20, 2014
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I came across an answer in my TBR book that says "While it is true that allotropes have different interatomic bonding, bonds are not broken during a phase change.."
I did not know this. But many sources that I looked at online explain phase changes in terms of bonds breaking....
 

theonlytycrane

5+ Year Member
Mar 23, 2014
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Medical Student
I mean, think liquid to gas. Intermolecular bonds have to break to free up the individual gas molecules.
 

aldol16

2+ Year Member
Nov 1, 2015
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H-bonds do break when the molecules undergo a phase change, but covalent bonds do not break. That is the source of the confusion. Covalent bonds have high BDEs (usually in the 100 kcal range for nonpolar bonds) and are hard to break. H-bonds have low BDEs (in the range of 5 kcals or so) and so do break during a phase change.
 
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