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Distillation
• Distillation is a process of separating a
mixture of liquids by boiling it.
Crude Oil
Formation, Composition,
Purification and Properties
Formation of Oil
1. Crude oil is found in the Earth’s crust
2. It was formed from the remains of sea
creatures that lived millions of years
ago
3. It is a fossil fuel
Formation of oil and gas
1) Layers of
dead sea _____
settle on the
seabed.
2) Layers of
__________
rock build up on
top.
3) The heat and ________ from
these rocks, along with the
absence of ______, mean that oil
and gas are formed over ______
of years.
Words – sedimentary, millions, oxygen, creatures, pressure
Formation of Oil
Finding Oil
Crude Oil
1. Crude oil contains a mixture of
hydrocarbons
2. Hydrocarbons have different lengths
and therefore different boiling points
3. They can be separated by fractional
distillation
4. Each fraction is put to a different use
depending on the properties of the
hydrocarbon
Crude Oil
Distillation
Uses of hydrocarbons
Most of the hydrocarbons present in
crude oil can be used as fuels because
they burn easily and give out a lot of
heat energy.
As the chain length increases they
become less flammable and so
purification is aimed to make simple
mixtures containing similar molecules
with similar behaviour.
Fractional Distillation
Fractional distillation
Crude oil can be separated by fractional distillation. The oil is evaporated
and the hydrocarbon chains of different lengths condense at different
temperatures:
Fractions with
low boiling
points condense
at the top
Fractions with
high boiling
points condense
at the bottom
Hydrocarbons
1. A hydrocarbon is a molecule which
contains hydrogen and carbon atoms
only
2. The longer the carbon chain the;
• Higher the boiling point
• Less volatile it is
• More viscous it is
• Less flammable it is
Comparing hydrocarbons
Which is a correct statement about crude oil?
A.
B.
C.
D.
A mixture of carbohydrates.
Formed by the decay of dead sea creatures.
Consist of a mixture of very large molecules.
Is purified in an oil rig.
© Boardworks Ltd 2003
Which is a correct statement about fractional
distillation?
A. Oil is separated into fractions with the same size
molecule.
B. Oil is separated into fractions with the same
density.
C. Oil is separated into fractions with similar size
molecules.
D. Oil is separated into alkanes and alkenes.
© Boardworks Ltd 2003
Which is a correct order for these fractions working
down from the top of the column?
A.
B.
C.
D.
Fuel gas, kerosine, petrol, diesel, bitumen.
Fuel gas, diesel, kerosine, petrol, bitumen.
Fuel gas, petrol, diesel, kerosine, bitumen.
Fuel gas, petrol, kerosine, diesel, bitumen.
© Boardworks Ltd 2003
Which of these is a true statement about the changes
that occur as hydrocarbon molecules get larger?
A.Boiling point decreases.
B.Viscosity increases.
C.Flammability increases.
D.Transparency increases.
© Boardworks Ltd 2003
Problems caused by burning hydrocarbons
1. When a hydrocarbon burns carbon
dioxide and water are made.
2. E.g. CH4 + 3O2 → CO2+ 2H2O
3. Carbon dioxide adds to the
greenhouse effect.
4. All fuels also contain sulphur
impurities from the original sea
creatures. When the sulphur burns in
an engine sulphur dioxide is made.
5. Sulphur dioxide adds to acid rain