Physical Properties of some functional groups: Intermolecular forces and water solubility

The strength of intermolecular forces in molecules with functional groups depends on:

• polarity
• capability of hydrogen bonding

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Organic molecules can be:

1. Nonpolar

   1. the strongest IMF in nonpolar molecules is dispersion forces
   2. nonpolar organic molecules include hydrocarbons, alkanes, alkenes, alkynes, aromatic hydrocarbons

2. Polar

   1. strongest force of attraction between molecules is dipole-dipole interactions
   2. organic molecules with oxygen & nitrogen are usually polar molecules

3. Capable of hydrogen bonding

   1. include alcohols, amines, carboxylic acids, amides
   2. strongest attractive force in all of functional groups

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Order of boiling points (1 is highest BP and 4 is lowest BP):

1. carboxylic acids & amides
2. alcohols
3. aldehydes & ketones
4. hydrocarbons & ethers

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Order of water solubility (1 is highest and 5 is lowest):

1. carboxylic acids & amides
2. alcohols
3. aldehydes & ketones
4. ethers (this is because ethers can accept hydrogen bonding while hydrocarbons can’t)
5. hydrocarbons

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