How do you test for a...

Question 1

alkane or alkene

Answer 1

• add a few drops of bromine water to the sample and shake, the bromine water should decolourise if it is an alkene

Question 2

test for a haloalkane

Answer 2

• silver nitrate
• ethanol
• water
  white precipitate - indicates chloro
  cream precipitate - indicates bromo
  yellow precipitates - indicates iodo

Question 3

Test for carbonyl

Answer 3

• acidified potassium dichromate - ketone would have no change, aldehyde turns from orange to green
• Fehling’s solution - ketone no change, aldehyde have a dark red precipitate
• Tollens’ reagent - ketones would have no silver mirror, aldehydes would have a silver mirror

Question 4

Test for carboxylic acid

Answer 4

• universal indicator - pH of a weak acid
• reactive metal - hydrogens
• metal carbonate - carbon dioxide

Question 5

Test for an alcohol

Answer 5

• warm with an equal volume of carboxylic acid and a few drops of sulphuric acid
• sweet smell of an ester over time