Ch_322a_2.011

Ch_322a_2.011 - BP solubility in 1.69 D 2.69 D-115 o C-121...

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Hydrogen Bonds Hydrogen bonding is a particularly strong type of intermolecular interaction. The hydrogen attached to highly electronegative atoms (F,O,N) is very electropositive . This hydrogen is attracted to the electronegative atom (F,O,N) in a second molecule forming a hydrogen bond . These bonds are estimated to have dissociation energies between 1-9 kcal/mole, and are a stronger stabilizing influence on the condensed states than simple dipole-dipole interactions. Example: Ethyl Alcohol CH 3 CH 2 O-H O H CH 3 CH 2 ! + !" O H CH 3 CH 2 ! + !" O H CH 3 CH 2 ! + !"
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The Influence of Hydrogen Bonds on Physical Properties Alcohols have higher boiling points than other polar compounds of comparable size because they form hydrogen bonds in the liquid state that are lost in the gas state. CH 3 CH 2 OH CH 3 CH O = MW dipole moment MP
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Unformatted text preview: BP solubility in water 46 44 1.69 D 2.69 D-115 o C -121 o C 78.5 o C 20 o C miscible miscible Hydrogen bonding raises the boiling point because a network of intermolecular bonds (1-9 kcal/mol) must be broken in the transition from the liquid to the gas state. Note this network is not broken in the transition from the solid to the liquid state, as revealed by the similar melting points of acetone and acetaldehyde. Quiz 2.011 In each pair of structures below, circle the one with the higher boiling point, and indicate the intermolecular attractive force responsible for the difference. CH 3 CH 2 CH 2 CH 3 CH 3 CH 2 CH O = CH 3 CCH 3 O CH 3 CH 2 CH 2 OH CH 3 CH 2 CH 2 OH CH 3 CH 2 OCH 3 dipole-dipole hydrogen bonding hydrogen bonding...
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Ch_322a_2.011 - BP solubility in 1.69 D 2.69 D-115 o C-121...

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