The carbon-carbon double bond will open up and add additional atoms on
New atoms are added to each carbon
Reactions with hydrogen:
Open up the double bond and form the equivalent saturated alkane
Needs a catalyst
Reaction with steam/water:
Water is added across the double bond and an alcohol is formed
* For example ethene and water makes ethanol
* After reactions, mixture is passed from the reactor into a condenser
* Ethanol and water have a higher boiling point then ethene so both condense whilst any unreacted ethene gas is recycled back into the reactor
* Alcohol can then be purified through fractional distillation
Reactions with halogens
Halogens include bromine, chlorine and iodine
Molecules formed are saturated, with the C=C carbons each becoming bonded to a halogen atom
Form di(halogen-ine)(alkane)
Test for alkene:
The addition of bromine to a double bond can be used to test for alkenes
* When orange bromine water is added to a saturated compound, like an alkene, no reaction will happen and it remains bright orange
* If it’s added to an alkene the bromine will add across the double bond making a colourless dibromo-compound, so the bromine water is decolourised