Question

Suggest a simple chemical test to distinguish propane and propene.

Answer 1

Propene is an alkene, whereas propane is an alkane. Thus, propene is an unsaturated molecule, having a carbon-carbon double bond. If you add bromine water, an aqueous solution of bromine, to the test tubes, you can tell which is propene, the alkene. The bromine reacts with and saturates the double bonds in alkenes, and so decolourises. The bromine does not decolourise when added to an alkane as it does not react. So, in conclusion:

Add $brominewater$ (brown) to the test tubes

If the bromine water stays brown, the test tube contains propane

If the bromine water goes colourless, the test tube contained propene.