Practical 6

• How to test for alkenes?

  Test: Shake with bromine water

  Result: Orange solution to colourless solution
• How to test for primary and secondary alcohols?

  Test: Warm with acidified potassium dichromate(VI)

  Result: Orange solution to green solution (OMG)
• What can also be tested with acidified potassium dichromate(VI) other than primary and secondary alcohols?

  Aldehydes as it would be oxidised to a carboxylic acid
• Why do tertiary alcohols show no reaction with potassium dichromate(VI)?

  It cannot be oxidised
• How to test for aldehydes and ketones?

  Test: Warm with Tollen's reagent or Fehling's solution

  Tollen's: Colourless solution to silver mirror and no change with ketone

  Fehling's: Blue solution to red precipitate with aldehyde and no change with ketone
• How to test for carboxylic acid?

  Test: Add sodium carbonate

  Result: Effervescence and carbon dioxide produced which turns limewater cloudy
• How to test for halogenoalkanes?

  Test: Warm with acidified silver nitrate

  Result: Chloride forms white ppt, bromide forms cream ppt, iodide forms yellow ppt