Alkenes

• Unsaturated hydrocarbons.
• Made by cracking long chained alkanes.

unsturated - one pair of arbon atoms are joined by a double covalent bond (C=C)

Alkenes from C → C4:

• C2H4 ethene
• C3H6 propene

The general formula for an alkene is:

Cn H2n

• Alkenes are more reactive than Alkanes due to the C=C bond.

Types of reactions that alkene undergo is called addition (with bromide water) - 

• Ethene + Bromine water → 1,2 dibromo ethane
• Propene + Bromine water → 1,2 dibromo propane

• Alkanes do not react with bromine water so this can be used to test for an alkene.

orange / brown → colourless

Alkenes will…