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How is petrol obtained from crude oil?
By fractional distillation
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In a petrol engine the mixture is ignited by a ____?
spark
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What used to be added to petrol to stop the mixture auto-igniting?
Lead
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What did auto-igniting cause the engine to do?
"knock"
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The naptha fraction is ________ to produce the mixture of hydrocarbons needed to add to petrol?
reformed
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What kind of molecules are found in petrol?
Alkanes, branched chain alkanes, cycloalkanes and aromatics
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In petrol, why are smaller molcules used in winter than in summer?
As they need to evaporate more easily in the colder temperatures
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Are fossil fuels finite or infinite?
Finite
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What are the four alternative fuels?
Methanol, ethanol, biogas and hydrogen
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How is ethanol made?
This is made by fermenting sugar cane
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Is ethanol renewable?
Yes
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Give one advantage and one disadvantage of methanol
- Advantages
- Carbon monoxide emissions are reduced
- Benzene vapour or other aromatic hydrocarbons are not released into the air
- Methanol is relatively cheap
- Methanol is less volatile and so less likely to explode in a car collision
- Disadvantages
- Methanol is toxic
- Methanol produces less energy than petrol
- Methanol absorbs water to produce a corrosive mixture
- It is difficult to get methanol to mix with petrol
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How is biogas made?
This is made by anaerobic respiration / incomplete fermentation of some biological matter like plant and animal waste eg manure and straw
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How can hydrogen be obtained?
By electrolysing water (using solar power)
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What is the main advantage of burning hydrogen?
It only produces water when burned
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