Test for Unsaturation (Cambridge International AS Chemistry)

Test for Unsaturation

• Halogens can be used to test if a molecule is unsaturated(i.e. contains a double bond)
• Br₂ (aq) is an orange or yellow solution, called bromine water and this is the halogen most commonly used
• The unknown compound is shaken with the bromine water
• If the compound is unsaturated, an addition reaction will take place and the coloured solution will decolourise

The unsaturation test

The decolourisation of bromine water by an unsaturated compound as a result of an addition reaction