Dear Student
Both alkyl halides and water are polar molecules.The intermolecular force of attractions between two alkyl halide molecules is dipole-dipole attraction. While The intermolecular force of attractions between two water molecules is by hydrogen bonding. When alkyl halides are mixed with water a new force of attraction between the alkyl halides and water comes into play, this new force of attraction is much weaker than the forces of attractions already existing between two alkyl halide and two water molecules respectively. This is the reason that alkyl halides, though polar, are immiscible with water.
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