practical 5b

Cards (8)

  • Write a word and symbol equation for the oxidation of ethanol to ethanal.
    Word: Ethanol + [O] → ethanal + water
    Symbol: CH3CH2OH + [O] → CH3CHO + H2O
  • With reference to the structure of ethanol and ethanal, and intermolecular forces, explain how distillation is able to separate ethanal from the mixture.
    > Ethanol has hydrogen bonding between the molecules
    > Dipole-dipole forces are weaker than hydrogen bonding and they require less heat energy to overcome
    > Ethanal has a lower boiling point than ethanol and ethanal can be separated from the mixture using distillation
  • State the role of the anti-bumping granules.
    To create small bubbles to ensure smooth boiling
  • State why the mixture in the round bottom flask should not be heated with a naked flame.
    Organic compounds such as ethanol are flammable and they will set on fire
  • Suggest two ways in which the yield of ethanal could be maximised.
    > Add acidified potassium dichromate(VI) dropwise to ethanol
    > Heat the mixture at the boiling point of ethanal
    > Cool the receiving flask with an ice bath
  • State the test for ethanal and the observation if it is present.
    Warm with Tollen’s reagent and a silver mirror should be produced
  • State the test for a carboxylic acid and the observation if it is present.
    Add sodium carbonate and fizzing should be observed
  • Ethanol can be oxidised to a carboxylic acid by reacting it with acidified potassium dichromate (VI) under reflux. Explain why a mixture is refluxed.
    To heat a mixture at a high temperature without the loss of reactants and products