CRACKING

CRACKING

1. Smaller molecules are made from larger molecules

2. Saturated molecule changes to a smaller unsaturated molecule and a saturated molecule

   • Saturated - all single bonds

3. Heat is used to vapourise the molecule

   • Vapourise - change a liquid to a gas by heating
   • Vapours pass over a hot catalyst
     • Catalyst - a chemical which makes a reaction go faster

4. Can be used as a way of making FUELS and POLYMERS

5. Makes alkenes

   • Ethene is an alkene
     • Used to make
       • Ethanol
         • Fermentation is another way to make ethanol
           • Sugar--> Carbon dioxide + Ethanol
             • Sugar is RENEWABLE
             • Yeast is needed for this reaction
         • Ethene + Steam --> Ethanol
           • HYDRATION
       • Polymers e.g. poly(ethene)
         • New packaging materials
         • Waterproof coating for fabrics
         • Polymerisation
           • Small to large
         • Monomers change to polymers
         • Dental polymers
         • Shape memory polymers
         • Not biodegradable
           • Causes problems at landfill sites
   • Unsaturated molecules
     • Carbon to carbon double bond
     • C=C
     • Use bromine water as a test
       • Orange to colourless would be seen
   • CnH2n

6. THERMAL DECOMPOSITION