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Fractional distillation of crude oil (QUESTION (State why crude oil can be…
Fractional distillation of crude oil
crude oil
is not runny enough or ignited easily enough for it to be a useful fuel
the different hydrocarbons it contains must be separated into simpler, more useful mixtures
achieved using fractional distillation
different hydrocarbons have different boiling points
QUESTION
State why crude oil can be separated using fractional distillation
the different hydrocarbons in it has different boiling points and so can be separated
Explain where changes of state happen during fractional distillation of crude oil
in the fractioning column
Describe the properties of kerosene that make it suitable for use as an aircraft fuel.
it does not ignite too easily and is not too viscous as well as this it has a low melting point so will not freeze in the air
Describe the relationship between the number of carbon atoms in a hydrocarbon molecule and the physical properties of the hydrocarbon.
the more carbon molecules there are the higher the boiling point, the more difficult it is to ignite and the more viscous it is
Petrol and fuel oil are different fractions separated from crude oil. Describe the difference in one physical property between these two fractions. (2 marks)
petrol has a lower boiling point than fuel.
How does fractional distillation of crude oil work?
all the different hydrocarbons have different boiling points and so separate
What do the substances in a crude oil fraction have in common?
similar amounts of carbon and hydrogen atoms and boiling points
How is crude oil made into useful mixtures?
it is fractionally distilled into different oil fractions which are suitable to fuel certain things such as gases for heating and cooking and into petrol for vechiles
Describe how the hydrocarbons in different fractions differ from each other.
they differ in the number of carbon and hydrogen atoms as well as in boiling points, viscosity, ease of igniting
In the fractionating column
where industrial fractional distillation of crude oil happens
a tall metal column
crude oil is heated strongly to evaporate it
the hot vapours are piped into the bottom of the column
the column is hottest at the bottom and coldest at the top
the vapours rise through the column and cool down
the vapours condense when they reach a part of the column that is cool
the liquid falls into a tray and is piped away
the vapours with the lowest boiling points do not condense at all and leave at the top as a mixture of gases
bitumen has the highest boiling point and leaves at the bottom as a hot liquid
the separate liquids and gases are called oil fraction
Lowest boiling points to highest
gases
domestic heating and cooking
petrol
fuel for cars
kerosene
fuel for aircraft
diesel oil
fuel for some cars and trains
fuel oil
fuel for large ships and power stations
bitumen
surfacing roads and roofs
Properties of fraction
each fraction is a mixture of hydrocarbons
rather than a pure hydrocarbons
the hydrocarbons in a given fraction
have similar numbers of carbon and hydrogen atoms in their molecules
have similar boiling points
different fractions have different properties
hydrocarbons in the gases fraction
suitable fuels
have the lowest viscosity
easiest to ignite
bitumen
suitable for surfacing roads and roofs
solid at room tempreature
waterproof
Lowest boiling points to highest
gases
smallest number of atoms, lowest boiling point, easy to ignite, lowest viscosity
petrol
kerosene
diesel oil
fuel oil
bitumen
largest number of atoms, highest boiling point, difficult to ignite, highst viscosity