Effect of intermolecular hydrogen bonding

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Discussion Overview

The discussion revolves around the effect of intermolecular hydrogen bonding on the states of matter, particularly focusing on the relationship between hydrogen bonding and the liquid state of substances like water. Participants explore how hydrogen bonding influences molecular packing and the resulting physical state of a substance.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants question how intermolecular hydrogen bonding, which promotes closed packing of molecules, can lead to a liquid state instead of a solid state.
  • Others argue that while hydrogen bonding contributes to the solid state at lower temperatures, in the liquid state, some water molecules remain linked by hydrogen bonds, creating localized clusters that exhibit some order.
  • A participant notes that the boiling points of hydrides in the oxygen family show a trend where water's high boiling point is attributed to strong hydrogen bonding compared to other hydrides like H2S.
  • It is suggested that the presence of solutes can alter the hydrogen bonding structures in water, impacting the behavior of water molecules in various environments, including around proteins.

Areas of Agreement / Disagreement

Participants express differing views on the implications of hydrogen bonding for the liquid state, with no consensus reached on how these interactions fully explain the behavior of substances like water.

Contextual Notes

The discussion highlights the complexity of hydrogen bonding and its effects on molecular interactions, with some assumptions about temperature and molecular behavior remaining unaddressed.

gracy
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Effect of intermolecular hydrogen bonding is as follows
hydrogen bonding.png

I don't understand one point i.e how occurrence of liquid state is associated with intermolecular hydrogen bonding
as intermolecular hydrogen bonding helps in closed packing of molecules it should give rise to solid state.
 
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gracy said:
it should give rise to solid state.

And it finally does when the temperature gets low enough. But even when water is in the liquid form some molecules are linked by hydrogen bonds. Not all, and there is no lattice going throughout the liquid, but locally clusters of several molecules can be quite ordered.
 
gracy said:
Effect of intermolecular hydrogen bonding is as follows
View attachment 82608
I don't understand one point i.e how occurrence of liquid state is associated with intermolecular hydrogen bonding
as intermolecular hydrogen bonding helps in closed packing of molecules it should give rise to solid state.

What you are looking at is probably a list of periodic trends for the oxygen family hydrides (H2O, H2S, H2Se, etc...) As you move up the column, the boiling points decrease. H2S is a gas at room temperature, you would predict (based upon the trend) that H2O would also be a gas, and have an even lower boiling point. The fact is that it is a liquid at room temperature and it has a very high boiling point. The reason for both of these observations is attibuted to the relatively strong interactions between the water molecules, compared with H2S, etc. and the rest of the members of the series. These strong interactions are called hydrogen bonds.
 
Borek said:
And it finally does when the temperature gets low enough. But even when water is in the liquid form some molecules are linked by hydrogen bonds. Not all, and there is no lattice going throughout the liquid, but locally clusters of several molecules can be quite ordered.

Plus anything you put into the water, polar or non polar, changes these structures or creates others. Around proteins for instance sometimes some water molecules are immobilized enough to be characterized as fixed structures by X-ray crystallography. Elementary and semi-elementary texts focus possibly overmuch on molecules alone when it is molecules in their solvent environment that are the thing to explain or the thing that explains IMHO. In short - never forget the solvent!
 
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