melting points
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melting points
why is H2O's melting point 0 degrees C while H2S has a melting point of -86 degrees C?
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Re: melting points
Water molecules undergo intense hydrogen bonding between the oxygen and hydrogen atoms. This makes it significantly harder for the intermolecular forces to be overcome to melt ice. Conversely, H2S has dipole-dipole interactions (S being negative and H positive). While these dipole-dipole interactions are important, they are not nearly as strong as the hydrogen bonding in H2O, and hence, the lower melting point.
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Re: melting points
Another way to think about it is that O is more electronegative than S, so its dipole moments are more dramatic than H2S's. The positive and negative ends form stronger bonds because of it.
Re: melting points
So hydrogen bonds make the molecule harder to break apart? So then they have a higher boiling point?
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Re: melting points
905416023 wrote:So hydrogen bonds make the molecule harder to break apart? So then they have a higher boiling point?
Yes, the strength of hydrogen bonds causes the molecules to have a greater intermolecular attraction which increases their melting and boiling points.
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Re: melting points
Hydrogen bonds are stronger than dipole/dipole or induced dipole/induced dipole interactions. H2O has the ability to hydrogen bond with itself because of the H-O bond, while H2S cannot. This accounts for H2O's higher melting point.
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