Organic analysis

• Test for functional groups pt1

  Alkenes

  • Test for alkenes is adding bromine water and shaking
  • Positive result is colour change from brown to colourless
• Test for functional groups pt2

  1°/2° alcohols

  • Add acidified potassium dichromate
  • Positive result is the colour change orange to green
• Test for functional groups pt3

  Aldehydes (There's three test)

  • Tollens's reagent
  • Positive result is a silver mirror forming
  • Fehling's reagent
  • Positive result is a brick red precipitate forming
  • Add acidified potassium dichromate
  • Positive result is a colour change to green from orange
• Test for functional groups pt4

  Carboxylic acids

  • pH or universal indicator
  • Positive result is a colour change to red, orange or yellow
  • Add a metal carbonate
  • Forms effervescence and turns limewater cloudy
• Test for functional groups pt5

  Haloalkanes/Halogenalkanes

  • Add nitric acid and acidified silver nitrate
  • Fluorine forms no precipitate
  • Chlorine forms a white precipitate
  • Bromine forms a cream precipitate
  • Iodine forms a yellow precipitate
  • Add dilute ammonia solution to dissolve the chlorine ppt
  • Add concentrated ammonia solution to dissolve the bromine ppt
• For the aldehydes and alcohols test you would also need to heat up the chemicals
• Effervescence is just gas bubbles
• For halogens, nitric acid is added first to remove any soluble carbonate ions CO3 2-. Before it reacts with the Ag+ in silver nitrate. The formula for that reaction is:

  CO3 2- (aq) + 2H+ + 2NO3 -(aq) ---> CO2 (g) + H2O (l) + 2NO3 -(aq)