AQA GCSE Science & Additional Science Chemistry 1 Topic 4 Hodder Education Revision Lessons Crude...
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Transcript of AQA GCSE Science & Additional Science Chemistry 1 Topic 4 Hodder Education Revision Lessons Crude...
AQA GCSE Science & Additional Science
Chemistry 1 Topic 4
Hodder Education Revision Lessons
Crude oil and fuelsCrude oils and fuels
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AQA GCSE Science & Additional Science
Chemistry 1 Topic 4
Overview — crude oil
• Crude oil is derived from an ancient biomass found in rocks. • Many useful materials can be produced from crude oil. • Crude oil can be fractionally distilled. Some of the fractions
can be used as fuels.
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What useful materials can be made from crude oil?
AQA GCSE Science & Additional Science
Chemistry 1 Topic 4
Overview — biofuels
• Biofuels are produced from plant material. • There are advantages and disadvantages to their use as
fuels. • Fuels can come from renewable or non-renewable resources.
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What are the advantages and disadvantages of biofuels?
AQA GCSE Science & Additional Science
Chemistry 1 Topic 4
Crude oil
Crude oil is a mixture of a large number of compounds.
A mixture consists of two or more elements or compounds not chemically combined together. The chemical properties of each substance in the mixture are unchanged.
It is possible to separate the substances in a mixture by physical methods, including distillation.
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Why does crude oil have so many different compounds in it?
AQA GCSE Science & Additional Science
Chemistry 1 Topic 4
Hydrocarbons 1Most of the compounds in crude oil consist of molecules made up of hydrogen and carbon atoms only (hydrocarbons).
Most of these are saturated hydrocarbons called alkanes, which have the general formula CnH2n+2.
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What would a model of ethane (two carbons) look like?
A molecular model of methane and its structural formula
AQA GCSE Science & Additional Science
Chemistry 1 Topic 4
Hydrocarbons 2
The many hydrocarbons in crude oil may be separated into fractions by evaporating the oil and allowing it to condense at a number of different temperatures.
Each fraction contains molecules with a similar number of carbon atoms.
This process is called fractional distillation.
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AQA GCSE Science & Additional Science
Chemistry 1 Topic 4
Fractional distillation
Explain how the fractionating column works.
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AQA GCSE Science & Additional Science
Chemistry 1 Topic 4
Properties 1Some properties of hydrocarbons depend on the size of their molecules. Look at the table below and on the next slide. What patterns do you notice?
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Fraction
Carbon atoms
in the molecule Description
Boiling
point (C) Flammability Uses
Petroleum
gas
1–4 Colourless gas Less than 40 Explodes if
mixed with air
and lit
Used as a fuel in
the refinery
Bottled and sold
as LPG
Naphtha 5–10 Yellowish liquid,
flows easily
25–175 Evaporates
easily, vapour
mixed with air
is explosive
Petrol
Used for making
other chemicals
Kerosene 10–14 Yellowish liquid,
flows like water
150–260 Burns when
heated
Aircraft fuel
AQA GCSE Science & Additional Science
Chemistry 1 Topic 4
Properties 2
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Fraction
Carbon
atoms in
molecule Description
Boiling
point (C) Flammability Uses
Light gas
oil
14–20 Yellow liquid,
thicker than
water
235–360 Only burns when
soaked onto a wick
or other material
Diesel fuel
Heavy gas
oil
20–50 Yellow brown
liquid
330–380 Only burns when
soaked onto a wick
— very smoky
Used in the
catalytic cracker
Lubricants
(car engine
oils)
50–60 Thick brown
syrup-like liquid
340–575 Only burns when
hot and soaked
onto a wick
Grease for
lubrication
Catalytic cracker
Fuel oil 60–80 Thick brown
sticky liquid
Above 490 Only burns when
hot and soaked
onto a wick
Fuel oil for power
stations and
ships
Bitumen More than 80 Black semi-solid Above 580 Only burns if very
hot
Road and roof
surfaces
AQA GCSE Science & Additional Science
Chemistry 1 Topic 4
Hydrocarbon fuels 1
Most fuels, including coal, contain carbon and/or hydrogen and may also contain some sulfur.
The gases released into the atmosphere when a fuel burns may include carbon dioxide, water (vapour), carbon monoxide, sulfur dioxide and oxides of nitrogen.
Solid particles (particulates) may also be released.
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What problems do carbon dioxide, sulfur dioxide and particulates cause? (Answers on the next slide.)
AQA GCSE Science & Additional Science
Chemistry 1 Topic 4
Hydrocarbon fuels 2The combustion of hydrocarbon fuels releases heat.
During combustion, the carbon and hydrogen in the fuels are oxidised.
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• Sulfur dioxide causes acid rain.• Carbon dioxide causes global warming.• Solid particles cause global dimming.
How can these effects be reduced? (Answers on the next slide.)
AQA GCSE Science & Additional Science
Chemistry 1 Topic 4
Hydrocarbon fuels 3
Sulfur can be removed from fuels before they are burned, for example in vehicles.
Sulfur dioxide can be removed from the waste gases after combustion, for example in power stations using scrubbers.
Catalytic converters in the exhausts of vehicles reduce the release of nitrogen oxides.
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AQA GCSE Science & Additional Science
Chemistry 1 Topic 4
BiofuelsBiofuels, including biodiesel and ethanol, are produced from plant material, e.g palm oil. There are economic, ethical and environmental issues surrounding their use.
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What are the issues with biofuels?
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