why does water have a higher boiling point than ethanol? Watch

smetin92
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i think i know a little bit:

ethanol is a slightly larger molecule than water, so in a fixed volume, fewer ethanol molecules can fit into the space, so fewer H bonds form between the molecules. however, for water, they are smaller the reverse cn be seen. i dont what else to say in terms of dipoles etc....
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iceman_jondoe
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(Original post by smetin92)
i think i know a little bit:

ethanol is a slightly larger molecule than water, so in a fixed volume, fewer ethanol molecules can fit into the space, so fewer H bonds form between the molecules. however, for water, they are smaller the reverse cn be seen. i dont what else to say in terms of dipoles etc....
the hydrogen bonding between the molecules of water is higher than the bonding between the molecules of ethanol which means more heat energy is required to break the bonds of molecules of water which leads to the increase in collision of the water molecules there by increasing the boiling point.
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Logan
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for water all three molecules are able to form hydrogen bonds with adjacent molecules. Ethanol has got 2 carbons, lots of hydrogen, and just one oxygen - in laymans term it is huge as youve said. As you said, its all about the dipole moment of water, i.e. higher internal energy thus waters high specific heat capacity (energy required to put it up by 1°C)
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smetin92
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(Original post by iceman_jondoe)
the hydrogen bonding between the molecules of water is higher than the bonding between the molecules of ethanol which means more heat energy is required to break the bonds of molecules of water which leads to the increase in collision of the water molecules there by increasing the boiling point.
I do not understand what you mean by the hydrogen bonding is higher? do you mean there are more of them, or they are stronger?
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dan9
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water can form two hydrogen bonds due to there being 2 delta posotive hydrogens incurred by the electronegative oxygen atom. Water therefore has more permanent-permanent dipole attractions which take more energy to break than the energy required to break the intermolecular bonds in ethanol. Thus water has a higher boiling point. hope this helps.
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purnima gupta
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i dont understand that why water and methane molecule does not form h bonding with each other
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Pigster
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This discussion is eight years old!

Anyhoo, to have H-bonding, you need an H atom attached to N or O or F. This leads to very polar N-H or O-H or F-H bonds. Leading to a very delta + H atom. This is then attracted to the lone pair on an N or O or F on another molecule.

C is not electronegative enough to create a large enough delta H, so can't form what you would call an H-bond to another molecule - water or not.
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