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H2O has very strong intermolecular forces due to the hydrogen bonds that a formed within the compound. Usually this would mean the compound has a very high melting point as a large amount of heat energy is required to overcome the forces, however H2O has a melting point of only O degrees. How come it is not a lot higher?

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    $\begingroup$ Because intermolecular forces in general are weak... Water has very high melting point for three atom molecule, with only light atoms. $\endgroup$ – Mithoron Aug 10 '16 at 1:23
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    $\begingroup$ 0 degrees is already very high for such a small molecule. Most molecules of similar mass are gases at 0 degrees. $\endgroup$ – f'' Aug 10 '16 at 2:30
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Melting points of the group 16 hydrides:

  • Water: 0 °C
  • Hydrogen sulfide: −82 °C
  • Hydrogen selenide: −65.73 °C
  • Hydrogen telluride: −49 °C
  • Polonium hydride: −35.3 °C

In theory, as the molecules grow larger (moving down in the group), their melting poits become higher too. Water is a clear outlier due to hydrogen bonding. Its melting point is already way higher than what should be expected looking at similar molecules.

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