Chemistry 2

Chemistry 2

1. Solid materials

   • melting point
   • strength in tension
   • stiffness
   • hardness
   • density
   • strength in compression

2. Crude oil

   • Refining Crude Oil
     • Crude Oil is a raw material obtained from the Earths crust
     • Mixture of many chemicals, many are Hydrocarbons
     • These are a chain of molecules of varying length that are made up of hydrogen and carbon atoms
     • crude oil is not very useful until it is processed through an oil refinary
     • Fractional Distillation
       • This is the process of refining which seperates hydrocarbons into fractions or batches
         • Each fraction separates as they have different boiling points
           • The crude oil is heated to about 400 degrees in a furnace
       • Smallest molecules in the crude oil have the lowest boiling points, this is because the forces between the molecules are so weak. so little energy is required to vaporise them.
         • The fractions gathered contain a mixture of hydrocarbons but are now useful.
           • majority of the fractions are used as different energy sources
           • boiling point of hydrocarbons increase as the number of carbon atoms in the molecule increase
             • Forces between the molecules increase as the size of molecules increase
       • Top of the tower is cooler and the bottom is hotter

3. Polymerisation

   • Some small molecules called monomers can join together to make long chains called polymers
   • Many polymers are made from chemicals that are obtained from crude oil
     • For eg. molecules of Ethane join together to Poly(ethene). Known as Polythene

4. Modifying Polymers

   • different Polymers have different properties
   • Plasticisers
     • Small molecules that can be added to polymers when they are being made, they push the polymer molecules, pushing the molecules slightly apart, weakening the force , making the material softer and flexible.
   • Cross Links

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