RP 06 Organic Tests

• How do you test for an alcohol?

  • Add 1cm^3 of alcohol to a test tube, and add a small piece of sodium
  • Presence of alcohol is indicated by a white precipitate and effervescence
• How do you distinguish between different alcohol types? (primary, secondary, tertiary etc)

  Heat under reflux with acidified potassium dichromate (VI). Primary and secondary alcohols will be oxidised - shown by a colour change from orange to green. Tertiary alcohols cannot be oxidised and will remain orange
• How do you test for an aldehyde?

  • Add Fehling's solution to the sample.
  • If an aldehyde is present, a red precipitate is formed
• How do you test for an alkene?romine water

  • Add bromine water to the sample
  • If alkene is present, the bromine water will decolourise
• How do you test for a carboxylic acid?

  • Add Na2CO3 to the sample
  • If a carboxylic acid is present, CO2 will be given off
• How do you test for a haloalkene?

  • Add 5 drops of haloalkene to about 1cm^3 of NaOH solution in a test tube.
  • Warm the contents of the tube at 60 degrees celsius for a few minutes
  • Then add 2cm^3 of dilute nitric acid and 1cm^3 of silver nitrate solution
  • If a haloalkene is present, a precipitate is formed - the colour of the precipitate formed depends on the halide ion present in the solution
• What are the colours of haloalkane precipitates?

  • chloride ions = white
  • bromide ions = cream
  • iodine ions = yellow