Petrol and alternative fuels
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How is petrol obtained from crude oil?
By fractional distillation
In a petrol engine the mixture is ignited by a ____?
What used to be added to petrol to stop the mixture auto-igniting?
What did auto-igniting cause the engine to do?
The naptha fraction is ________ to produce the mixture of hydrocarbons needed to add to petrol?
What kind of molecules are found in petrol?
Alkanes, branched chain alkanes, cycloalkanes and aromatics
In petrol, why are smaller molcules used in winter than in summer?
As they need to evaporate more easily in the colder temperatures
Are fossil fuels finite or infinite?
What are the four alternative fuels?
Methanol, ethanol, biogas and hydrogen
How is ethanol made?
This is made by fermenting sugar cane
Is ethanol renewable?
Give one advantage and one disadvantage of methanol
- 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
- 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
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
How can hydrogen be obtained?
By electrolysing water (using solar power)
What is the main advantage of burning hydrogen?
It only produces water when burned
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