Testing for Organic Functional Groups [RPA 6]

Question 1

Testing for Alkenes

Answer 1

Orange bromine water added
Sample shaken
If alkene, colourless solution forms
Electrophilic addition

Question 2

Testing for Alcohols

Answer 2

Add acidified potassium dichromate (K2Cr2O7, acidified with H2SO4)
Heat
Tertiary alcohols present, nothing happens
Primary or secondary alcohols present, orange to green

Question 3

Testing for Aldehydes

Answer 3

Tollens
- Warm
- Ammoniacal Silver Nitrate Solution
- Ag+ reduced to Ag atoms
- Silver mirror forms
.
Fehling’s solution
- Cu2+
- Reduced to Cu+
- Clear blue to opaque red

Question 4

Testing for Carboxylic Acids

Answer 4

Add Na2CO3
CO2 gas emitted
Test gas with limewater
Turns cloudy