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    1) if water can form london forces between other water molecules, why cant it dissolve organic substances by forming london forces with them???? i know about the hydrogen bonding but im talking about the london forces water can form..


    2) "both ethanol and water contain hydrogen bonds. by considering the hydrogen bonding on these two solvents, suggest why 2-chlorobutane is more soluble in ethanol than in water?? " the markscheme says bcz water has 2 hydrogen bonds per molecule whereas ethanol has one so water needs more energy to break H bonds in water ............ my question is that why did mention the less hydrogen bonds ethanol can form rather than mentioning that is has nonpolar characteristics which means that it can form london forces or dipole-dipole forces with 2-chlorobutane???
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    (Original post by pondsteps)
    1) if water can form london forces between other water molecules, why cant it dissolve organic substances by forming london forces with them???? i know about the hydrogen bonding but im talking about the london forces water can form..
    The magnitude of the London dispersion force is directly related to the atomic number sum (and hence the number of electrons).

    In water this is small, so the contribution of London forces to the intermolecular forces is very small. Water is primerily held together by hydrogen bonding and permanent dipole interactions.

    Large organic molecules cannot disrupt the intermolecular forces in water as the forces between water and a large covalent particle would be small.
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    (Original post by charco)
    The magnitude of the London dispersion force is directly related to the atomic number sum (and hence the number of electrons).

    In water this is small, so the contribution of London forces to the intermolecular forces is very small. Water is primerily held together by hydrogen bonding and permanent dipole interactions.

    Large organic molecules cannot disrupt the intermolecular forces in water as the forces between water and a large covalent particle would be small.
    okay thanks!!! what about 2)????
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    (Original post by pondsteps)
    1)

    2) "both ethanol and water contain hydrogen bonds. by considering the hydrogen bonding on these two solvents, suggest why 2-chlorobutane is more soluble in ethanol than in water?? " the markscheme says bcz water has 2 hydrogen bonds per molecule whereas ethanol has one so water needs more energy to break H bonds in water ............ my question is that why did mention the less hydrogen bonds ethanol can form rather than mentioning that is has nonpolar characteristics which means that it can form london forces or dipole-dipole forces with 2-chlorobutane???
    It's like I said in my other post.

    Solubility, or rather miscibility, depends on a three-way struggle.

    1. There are bonds between liquid A molecules
    2. There are bonds between liquid B molecules
    3. There are bonds between liquid A and liquid B molecules

    For something to be soluble it has to form bonds strong enough to disrupt the bonding in the two pure phases, otherwise each component keeps itself to itself.

    Chlorobutane can form polar bonds to ethanol which are strong enough to disrupt the H-bonding in ethanol, but its weak polar bonding to water is not strong enough to disrupt the stronger H bonding in water.
 
 
 

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