5 - Organic analysis

Question 1

Testing for alkenes

Answer 1

• Bromine water
  +ve result = orange to colourless

Question 2

Testing for Halogenoalkanes

Answer 2

• add NaOH and warm (Nucleo. sub. releases halide ions)
• acidify HNO₃
• add silver nitrate (AgNO₃)
• Precipitates
  AgF = No ppt
  AgCl = white ppt
  AgBr = cream ppt
  AgI = yellow ppt

Question 3

Testing for Alcohols

Answer 3

• Add acidified potassium dichromate
  +ve result = orange to green (only primary and secondary alcohols and aldehydes)

Question 4

Aldehydes

Answer 4

• warm with tollens
  OR
• warm with fehlings
  +ve fehlings = blue to red precipitate
  +ve tollens = silver mirror formed

Question 5

Carboxylic acid

Answer 5

• add sodium carbonate NaCO₃ or sodium hydrogen carbonate NaHCO₃
  +ve result = effervesence (CO₂) released