Chemistry / Unit 8 Chem 1419 short lesson, about 20 seconds
Enthalpy of Fusion and Enthalpy of Vaporization
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The idea
Enthalpy of fusion melts a substance at its melting point; enthalpy of vaporization vaporizes it at its boiling point, and is always the larger value.
In practice
Melting ice weakens hydrogen bonds enough to let molecules slide past each other; boiling overcomes those attractions almost completely.
Where people slip
Melting loosens a solid's structure; vaporization overcomes attraction nearly in full, a gap easy to underestimate.
Your place on the trail
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