Why are changes of state physical changes?

1 Answer
anor277
Jun 11, 2016

Because changes of state do not involve the making and breaking of strong chemical bonds.

Explanation:

Chemical change is characterized by the making and breaking of strong chemical bonds, and the formation of new substances (I've said this many times before here; forgive me, I can never find the link when I need to use it). When card ice sublimes, or when water boils, the weaker intermolecular forces are disrupted, but the strong #C=O# or #O-H# bonds remain unbroken. Since the molecule remains inviolate, no chemical bonds are broken in a phase change, and the transition is properly regarded as a physical change. Capisce?

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