Zusammenfassung der Ressource
C2 - Material Choices
- Crude Oil
- Mixture of hydrocarbons
- Molecules that are made of a chains of carbon and hydrogen atoms only.
- Varying chain length
- Properties
- As the length of the
hydrocarbon changes the
properties also change.
- When supplied heat the smaller molecules receive enough
energy to overcome the weak intermolecular forces
- Low mpt and bpt
- Longer chains need more energy
- Higher mpt and bpt
- Bonds in crude oil
- Strong covalent bonds
between the carbons and
hydrogens of the molecule
- Weak intermolecular molecular forces
of attraction between molecules
- Uses of Crude Oil
- Separated by
fractional distillation
- Most of the
hydrocarbons in
crude oil are used
to make fuels.
- Some are sued to
make new
compounds
- Plastics,
medicines,
fertilisers
and food
- Chemical synthesis
- The petrochemical industry
refines crude oil to produce
fuels and lubricants.
- It also produced raw
materials that can be used to
make synthetic chemicals
- Some less useful hydrocarbons
can be reacted with hydrogen so
that they split into more useful
hydrocarbons
- Polymers
- Polymerisation
- Plastics are formed when lots
of small molecules (monomer)
join together to make a very
long molecule (polymer)
- Carbon based
- Formed under high pressure
- Properties
- Polymers made from varying
monomers have different properties
- Strong and rigid
- HDPE
- Used to make milk bottles
- Light and stretchable
- LDPE
- Plastic bags and water bottles
- Strong and Durable
- PVC
- Rigid
- Window frames and piping
- Stretchy
- Synthetic leather
- Impact resistant
and soft
- Polystyrene
- Packaging
- Heat resistant
- Melamine resin and
polypropene
- Plastic Kettles
- Replacing natural materials
- Synthetic fibres are replacing
cotton, wool and silk
- Lighter, more durable,
water-resistant and often cheaper
- Rigid PVC has replaced wood
as a material for window frames
- Weather-resistant, strong,
durable, no painting
- Structure and
Properties of
Polymers
- Properties
- Depend on molecular
arrangement
- Density
- Polymers packed
together tightly =
high density
- Polymer chains are
spread out = low density
- Forces
- Weak forces
- Free to slide over each other
- Easily stretched
- Low mpt.
- Strong forces
- Inflexible
- higher mpt.
- Cross links
prevent free
movement
- Crosslinks
are chemical
bonds
- Modification
- Increase
chain length
- Stronger
- Cross-linking
- Stronger, stiffer, more
heat resistance
- Plasticisers
- Softer and easier to shape
- Work by reducing intermolecular forces
- Crystallinity
- Made more crystalline
- Strighter chains
with no branches
- Higher density
- Stronger and have higher mpt.
- B