Chapter 14 - Alcohols

• What is the functional group of the alcohols?

  hydroxyl group (-OH)

  
• State a use of ethanol

  alcoholic drinks, solvent, chemical feedstock
• Compare the physical properties of alcohols and alkanes

  alcohols are less volatile, have higher melting points, and are more soluble in water than corresponding alkanes
• What intermolecular forces act between alkanes?

  induced dipole-dipole interactions
• What intermolecular forces act between alcohols?

  induced dipole-dipole interactions and hydrogen bonds between hydroxyl groups
• Why are alcohols polar molecules?

  the oxygen and hydrogen in -OH have different electronegativities
• Describe and explain the boiling points of alcohols

  alcohols have higher boiling points than alkanes as strong hydrogen bonds must be overcome, which require more energy to break than induced dipole-dipole interactions

  
• What is a secondary alcohol?

  the -OH group is attached to a carbon atom which is attached to 2 other carbon atoms

  
• What is a primary alcohol?

  the -OH group is attached to a carbon atom which is attached to 1 other carbon atom

  
• What is a tertiary alcohol?

  the -OH group is attached to a carbon atom which is attached to 3 other carbon atoms

  
• Why are alcohols soluble in water?

  -hydrogen bonds form between polar -OH group and water

  
• What is the trend of solubility in alcohols?

  as hydrocarbon chain increases, the influence of -OH becomes smaller and solubility decreases
• How does quantity of heat released when alcohols are combusted relate to chain length?

  as chain length increases, the quantity of heat released per mole increases
• How can you identify if oxidation of an alcohol has taken place?

  a colour change from orange (dichromate (VI) ions) to green (chromium (III) ions)
• What is a suitable oxidising agent for alcohols?

  acidified potassium dichromate (H+/K2Cr2O7)
• How can an aldehyde be produced from an alcohol?

  -primary alcohol heated with acidified potassium dichromate and distilled out to prevent further oxidation to a carboxylic acid

  
• How can a carboxylic acid be produced from an alcohol?

  -primary alcohol heated strongly under reflux with an excess of acidified potassium dichromate to ensure complete oxidation

  
• Describe and explain the oxidation of a secondary alcohol

  heat under reflux with acidified potassium dichromate to ensure complete oxidation to a ketone

  
• Can tertiary alcohols be oxidised?

  no-acidified potassium dichromate remains orange
• What is produced from a dehydration reaction of an alcohol?

  in the presence of an acid catalyst, an alkene and water are produced

  
• How can a haloalkane be produced from an alcohol?

  -prepare a hydrogen halide by reacting sodium halide and sulfuric acid together

  -hydrogen halides react with alcohol to produce a haloalkane

  *heat sodium halide, sulfuric acid and alcohol under reflux to produce a haloalkane