ADDITION REACTIONS : is a reaction in which two or more molecules react to form a single product
The C=C group in Alkenes reacts with chemicals in addition reactions.
- ADDITION OF HYDROGEN
- Alkenes react with hydrogen to produce Alkanes.
- This reaction is called hydrogenation. A nickel (Ni) catalyst must be used.
- An example is the reaction of ethene with hydrogen.
- C2H4(g) + H2(g) ---> C2H6(g)
- ethene(g) + hydrogen(g) ---> ethane(g)
Hydrogenation is used to change vegetable oils into margarine.
- ADDITION OF BROMINEBromine reacts with ethene in an adition reaction. The bromine molecule adds t the C=C double bond of the ethene molecules.
- ADDITION OF WATER
- Alkenes react wth water to produce alcohols.
- A molecule of H2O adds to the C=C double bonds.
- This is done by passing a mixture of alkene and steam over a catalyst.
- An example is the addition of water to ethene, producing ethanol.
- C2H4(g) + H2O(l) ---> C2H5OH(l)
- ethene + water ---ethanol
- Alcohols are important solvents. They are also used to make other chemicals.