Alkanes and Alkenes

Aim: to compare the reactivities of alkane/alkene
Equipment: test tubes, test tube rack, 10mL measuring cylinder, cyclohexane & cyclohexene
1. pour 1mL of A into a test tube, 1mL of B into the second test tube
2. measure and pour 1mL of KMnO4 in both test tubes
3. observe whether there is a colour change, indicating a chemical reaction and that it is an alkene
4. rinse out both test tubes and repeat 1
5. measure and pour 1mL of bromine water in both test tubes
6. observe for colour change

Sample Reaction with Br. water Reaction with acidified KMnO4 Hydrocarbon
A Yes Yes Alkene
B No No Alkane

The two chemicals differ only by the double bond in cyclohexene, which can 'open up' to react, making it more reactive than cyclohexane. Cyclohexene and cyclohexane were chosen as they are liquid at room temperature and easy to handle as well as observe for colour changes.