qualitative functional group analysis

• functional group: alkene

  chemical test: add bromine water drop-wise

  observation: bromine water decolourised from orange to colourless
• FUNCTIONAL GROUP: haloalkane

  CHEMICAL TEST: add silver nitrate and ethanol and warm to 50 °C in a water bath

  OBSERVATION:

  1. chloroalkane - white precipitate
  2. bromoalkane - cream precipitate
  3. iodoalkane - yellow precipitate
• FUNCTIONAL GROUP: carbonyl

  CHEMICAL TEST: add 2,4-dinitrophenylhydrazine

  OBSERVATION: orange precipitate
• FUNCTIONAL GROUP: aldehyde

  CHEMICAL TEST: add Tollens' reagent and warm

  OBSERVATION: silver mirror
• FUNCTIONAL GROUP: primary/secondary alcohol and aldehyde

  CHEMICAL TEST: add acidified potassium dichromate (VI) and warm in a water bath

  OBSERVATION: colour change from orange to green
• FUNCTIONAL GROUP: carboxylic acid

  CHEMICAL TEST: add aqueous sodium carbonate

  OBSERVATION: effervescence