Anything written in purple is for higher tier
Exam tips are in red
Fossil Fuels
3 types
Coal (made from dead plants that lived millions of years ago)
Crude oil (made from dead sea creatures that lived millions of years ago)
Natural gas (made from dead sea creatures that lived millions of years ago)
Key words to learn
Non-renewable- fossil fuels are said to be this as we are using them up faster than they can be made
Finite- these will run out if we continue using them
Crude oil
This fossil fuel is made up of a mixture of hydrocarbons. Hydrocarbons are compounds that contain hydrogen and oxygen atoms only a) b)
In the exam you may be asked to identify hydrocarbons from their structure. You can see that a) is not a hydrocarbon as it contains oxygen as well
Crude oil on its own is not useful but the hydrocarbons it contains on their own are useful and so they need to be separated. They are separated by a process called fractional distillation and this happens in a fractionating column
You might have a diagram like the one above and you have to label the fractions in the order they come off the column and so learn them. You also need to learn what the fractions are used for
The fractionating column is heated at the bottom so the bottom is much cooler than the top of the column. The crude oil is piped into the fractionating column and heated.
In the exam you could be asked by what property difference are the different hydrocarbons (called fractions) separated by and the answer is Boiling Point
Small hydrocarbons have low boiling points so when the crude oil is heated, they travel to the top of the column and leave as a gas (LPG)
Hydrocarbons with the highest boiling points stay as a liquid and leave at the bottom of the column (bitumen). In the exam you could be ask to label where on the column bitumen leaves, and you would put an X on the tube at the bottom of the column)
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