Chapter 14

• What is the functional group of an alcohol?

  Hydroxyl group -OH
• What is the general formula of an alcohol?

  CnH2n+1OH
• How do you name alcohols?

  Use Hydroxyl- OR -ol as a prefix or suffix
• What kind of intermolecular forces do alcohols have and why?

  Hydrogen bonding, due to the electronegativity difference in the OH bond
• How do alcohols' melting and boiling points compare to hydrocarbons of similar carbon chain lengths?

  Alcohols have higher melting and boiling points due to hydrogen bonding
• Are alcohols soluble in water and why does solubility depend on chain length?

  Short-chain alcohols are soluble due to hydrogen bonding, while long-chain alcohols are not due to non-polarity
• What makes an alcohol primary?

  The carbon bonded to the OH group is only bonded to one other carbon atom
• What makes an alcohol secondary?

  The carbon bonded to the OH group is bonded to two other carbon atoms
• What makes an alcohol tertiary?

  The carbon bonded to the OH group is bonded to three other carbon atoms
• Write an equation for the combustion of ethanol.

  C2H5OH (l) + 3O2 (g) → 2CO2 (g) + 3H2O (l)
• What forms if you partially oxidise a primary alcohol?

  An aldehyde
• What conditions are needed to partially oxidise a primary alcohol?

  Dilute sulphuric acid, potassium dichromate (VI), distill product as it’s produced, gentle heating
• Write an equation for the partial oxidation of ethanol.

  CH3CH2OH (l) + [O] → CH3CHO (g) + H2O (l)
• What forms if you fully oxidise a primary alcohol?

  A carboxylic acid
• What conditions are needed to fully oxidise a primary alcohol?

  Concentrated sulphuric acid, potassium dichromate (VI), reflux, strong heating
• Write an equation for the full oxidation of ethanol.

  CH3CH2OH (l) + 2[O] → CH3COOH (g) + H2O (l)
• What forms if you oxidise a secondary alcohol?

  A ketone
• What conditions are needed for the oxidation of a secondary alcohol?

  Concentrated sulphuric acid, potassium dichromate (VI), strong heating
• Write an equation for the oxidation of propan-2-ol.

  CH3CH(OH)CH3 (l) + [O] → CH3COCH3 (g) + H2O (l)
• Is it possible to oxidise tertiary alcohol?

  No
• What is a dehydration reaction?

  A reaction where water is lost to form an organic compound
• What are the products of a dehydration reaction of alcohol?

  Alkene and water
• What are the conditions required for dehydration of alcohol?

  Concentrated sulfuric acid or concentrated phosphoric acid and 170°C
• What are the products of the halide substitution reaction with alcohol?

  Haloalkane and water
• In what form is the halide used in halide substitution reaction?

  In the form of hydrogen halide, e.g., HBr
• How is hydrogen halide made in situ? Give examples.

  A salt is reacted with acid to form the hydrogen halide, e.g., sodium bromide reacts with sulfuric acid to form HBr
• What happens when iodine is reacted with phosphoric acid?

  Phosphoric acid is used as sulfuric acid oxidises iodide ions into iodine
• What is the functional group present in alcohols?

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

  CnH2n+1OH

  
• What does 'n' represent in the general formula of alcohols?

  The number of carbon atoms
• How are alcohols named based on their structure?

  By replacing the ending "-e" of the corresponding alkane with "-ol"
• What is the purpose of a numerical prefix in alcohol naming?

  To indicate the position of the hydroxyl group
• How are alcohols classified based on the carbon atom to which the hydroxyl group is attached?

  • Primary alcohols: -OH attached to a carbon with one alkyl group.
  • Secondary alcohols: -OH attached to a carbon with two alkyl groups.
  • Tertiary alcohols: -OH attached to a carbon with three alkyl groups.

  
• Why is the bond between oxygen and hydrogen in the hydroxyl group of alcohols considered polar?

  Because oxygen is more electronegative than hydrogen
• What charge does the hydrogen atom acquire in the hydroxyl group of alcohols?

  A partial positive charge (δ+)
• What type of bonds can the partially positively charged hydrogen atom (δ+) form?

  Intermolecular hydrogen bonds
• What are the unique physical properties of alcohols due to the hydroxyl (-OH) group?

  1. Solubility: Small alcohols dissolve in water; larger alcohols have decreased solubility.
  2. Volatility: Alcohols have lower volatility (higher boiling points) than alkanes of similar size.
• Why do small alcohols like methanol to propanol dissolve in water?

  Because the hydroxyl group forms strong hydrogen bonds with water molecules
• Why are alkanes insoluble in water?

  Due to their lack of polar groups and inability to form hydrogen bonds
• How does the solubility of alcohols in water change with molecular size?

  It decreases as their molecular size increases