Heat of vaporisation help please

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    Heat Vaporisation
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The discussion centers on the significant difference between the heat of vaporization and the heat of fusion for water, highlighting that the heat of vaporization is nearly seven times greater. The explanation provided emphasizes that transitioning from ice to water requires relatively little energy because the molecular structure remains close, with only the attractive forces weakening. In contrast, converting liquid water to vapor necessitates a substantial increase in kinetic energy, allowing molecules to move freely apart. This process involves breaking various attractive forces, including hydrogen bonds, which are present in both liquid and solid states but absent in the gaseous state. The key takeaway is that while hydrogen bonding contributes to the energy required for phase changes, the dramatic increase in energy needed for vaporization is due to the complete rupture of these bonds and the resulting increase in molecular freedom.
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Hi, i am writing a assignment about thermal expansion and contraction
and i would like to know if anyone could explain to me why the heat of vaporisation is nearly seven times that of the heat of fusion for water. I thought it might be hydrogen bonding but this is present in both the liquid and solid phases. any help is appreciated
 
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To convert ice to water not much energy is needed because there is not much change. Only the bonds or attractive force get weaker but molecules are still close together but in vapor phase molecules gains so much of kinetic energy that they are free to move all around the spaces and so we need to give much more energy.
 
but isn't it the hydrogen bonding that keeps the molecules close together in the first place? I mean, water in its liquid and solid states has hydrogen bonding but not in the gaseous state, so i thought that is why there is so much more energy needed to get it from liquid to gas, to break those bonds
 
yeah, you are correct. Most of the attractive force get ruptured while we get from liquid to gaseous state. Hydrogen bonding is also one among those forces.
 
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