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5b & 5c) CRUDE OIL and SYNTHETIC POLYMERS (uses of the main fractions…
5b & 5c) CRUDE OIL and SYNTHETIC POLYMERS
the industrial process of fractional distillation of crude oil
Crude oil is heated, most fractions boil
They enter the fractionating column which is hot at the bottom and cool at the top
Hot gases rise; when the temperature falls below the boiling points they condense and are trapped and removed
N.B. each fraction is a mixture of hydrocarbons with similar boiling points
Bitumen never boils, it sinks to the bottom as a liquid
uses of the main fractions in crude oil
(in order of boiling point)
Refinary gases
Domestic heating/ cooking (e.g. methane propane)
Gasoline (petrol)
Fuel for cars
Kerosene
Aircraft fuel, paraffin lamps, domestic heaters
Diesel
Fuel for buses/lorries
Fuel oil
Ship boilers, industrial heating
Bitumen
Road repairs
the higher the boiling point the more carbon atoms with the molecule
Viscosity
viscosity is a measure of how thick a liquid is.
high viscosity = treacle like liquid
low viscosity = very runny
how an addition polymer forms
etc etc until the long chain is formed
The double bond on this second alkene partially breaks
The electrons from this form a single bond to another alkene molecule
The double bond of an alkene partially breaks
Combustion
is when a substance burns with Oxygen in the air
CO2 and H3O are produced
incomplete combustion
when there is not enough oxygen
H2O will always form but soot (C) and CO form instead of CO2
Carbon Monoxide (CO) is formed, which is poisonous
2CH4+3O2→2CO+4H2O
monomer=a small molecule which can combine with others of the same type to form a long chain
Polymer=a long chain molecule formed when many monomers join (bond) together
polymerisation=any reaction where a polymer forms. Addition polymerisation: when the monomers join together with no product other than the polymer
the name of a polymer is simply poly followed by the monomer name in brackets. NO other change is required e.g. ethene → poly(ethene) styrene → poly(styrene)/propene → poly(propene)
if a question asks for the repeat unit then there is no need for brackets
hydrocarbon=chemical containing only hydrogen and carbon
in car engines - nitrogen & oxygen reacting in air to create nitrogen oxides
N2 is a largely nonreactive gas so high temperatures are required for it to react with oxygen
NOx is used to represent the various nitrogen oxides which can form (e.g. NO, NO2, N2O4, N2O2)
issue with nitrogen oxides - smog and acid rain linked to formation of NOx
uses of hydrocarbons:
the supply of each fraction does not correspond to demand
the short chain hydrocarbons are the most useful, but long chain hydrocarbons form a higher proportion of crude oil
Cracking
**
used industrially
this process by which long chain alkanes are broken down into alkenes and shorter chain alkanes
they are heated over a suitable catalyst (silica or alumina) at 600 to 700 degrees C
e.g. C12+H26→C2H4+C10H22
C12H26→2C2H4+C8H18
C12H26→C4H8+C8H18