Alcohols

• What functional group do all alcohols contain?

  Hydroxyl (-OH) group
• What is the general formula for alcohols?

  CnH2n+1OH
• What type of bond gives alcohols a polar character?

  –OH bond
• What force is created between a hydrogen atom bonded to an oxygen atom on one alcohol molecule and a lone pair on an oxygen atom on another molecule?

  Hydrogen bonds
• How do short-chain alcohols dissolve in water?

  By forming hydrogen bonds with water molecules
• How does the solubility of alcohols change as chain length increases?

  Solubility decreases
• Why do alcohols have higher boiling points compared to alkanes and alkenes?

  They form hydrogen bonds
• What does it mean for alcohols to have a lower volatility compared to alkanes or alkenes?

  They are harder to convert from liquid to gas
• What are the three classes of alcohols?

  Primary, secondary, tertiary
• In a primary alcohol, how many other carbon atoms is the carbon bonded to which the –OH group is bound?

  One
• In a secondary alcohol, how many other carbon atoms is the carbon bonded to which the –OH group is bound?

  Two
• In a tertiary alcohol, how many other carbon atoms is the carbon bonded to which the –OH group is bound?

  Three
• What two products are released when alcohols are burned in combustion reactions?

  Carbon dioxide and water
• Why are alcohols considered good fuels?

  Combustion reactions are very exothermic
• Why is ethanol a more sustainable fuel than hydrocarbons from crude oil?

  It can be produced through glucose fermentation
• What is the oxidising agent used to oxidise alcohols?

  Acidified potassium dichromate
• What products are formed from the partial oxidation of primary alcohols and under what conditions does this occur?

  Products:

  • Aldehydes
  • Water

  
  

  Conditions:

  • Distillation (boiling off the aldehyde immediately)
• What is the byproduct formed from complete oxidation of primary alcohols into carboxylic acids?

  Water
• What apparatus is used to achieve complete oxidation of primary alcohols into carboxylic acids?

  Reflux apparatus
• What type of alcohol is oxidised into ketones?

  Secondary alcohols
• What other product besides the ketone, is formed when oxidising a secondary alcohol?

  Water
• What happens when you try to oxidise a tertiary alcohol?

  It cannot be oxidised
• Why can't tertiary alcohols be oxidised?

  No hydrogens to be removed for oxidation
• What ions cause the orange colour of potassium dichromate?

  Cr2O7 2-
• What colour change indicates the reduction of potassium dichromate during alcohol oxidation?

  Orange to green
• What ions cause the green colour after potassium dichromate is reduced?

  Cr3+
• If an orange to green colour change is seen when reacting an unknown alcohol with acidified potassium dichromate, what type of alcohol is it?

  Primary or secondary
• What conditions are required for the dehydration of alcohols to form alkenes?

  Warm temperatures and an acid catalyst
• What type of reaction removes water from alcohols to form alkenes?

  Dehydration reaction
• Name two acid catalysts that can be used for the dehydration of alcohols.

  Sulfuric or phosphoric acid
• What compounds react with alcohols to form halogenoalkanes?

  Compounds containing halide ions
• What type of reaction occurs when alcohols react with compounds containing halide ions to form halogenoalkanes?

  Nucleophilic substitution
• What type of catalyst is required for the reaction between alcohols and compounds containing halide ions to form halogenoalkanes?

  Acid catalyst
• What is another name for halogenoalkanes?

  Haloalkanes
• How can the oxidation of alcohols be used as a test to distinguish between primary/secondary and tertiary alcohols?

  Observe the colour change of the reaction