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Hydrocarbon
- A Hydrocarbon is a compound only containing Hydrogen and Carbon
- They can have single and double bonds, meaning they can be saturated or unsaturated.
- They have a variety of chain lengths
- Varied shapes
- Many are flexible and can move whilst still having fixed van der Waals, Covalent and Hydrogen bonds.
Alkane
- An Alkane is the simplest form of a hydrocarbon. Each Carbon atom has 4 bonded pairs.
- They have single bonds, therefore are saturated.
- They are insoluble in water
- Have a variety of chain lengths
- Rotate and bend easily
- Have the general formula CnH2n+2
- As the molecules get longer the more energy it takes to remove the inter/intramolecular forces holding the atoms together (either van der waals, covalent or hydrogen) therefore boiling point increases.
- Release large amounts of energy.
Crude Oil
- Crude oil is a mixture of long and short-chain hydrocarbons
- It if a non-renewable fossil fuel
- Crude oil , once in shorter chains can be condensed into Petrol, Kerosene, gas oil and many more.
- we use shorter chain hydrocarbons in everyday life, This means that we have to find a way to shorten or separate the hydrocarbons, this is done by:
- Cracking
- Fractional Distillation
You must know how Cracking and Fractional Distillation work in AS/A-level Chemistry exams! 👨🏫
Cracking
- This involves breaking the C-C bonds in the Hydrocarbon.
- The long, heavy hydrocarbons are passed over a catalyst and a very high temperature, this breaks the bonds forming smaller alkenes and Alkanes.
Fractional Distillation
- Fractional distillation is the separation of a mixture into its component parts, or fractions, such as in separating chemical compounds by their boiling point by heating them to a temperature at which several fractions of the compound will evaporate. It is a special type of distillation.
Crude oil is vaporised and sent into a tube. Depending on the boiling point of the hydrocarbons, the boiling points will ether be higher or lower, moving up or down the column. At certain temperatures the hydrocarbons move out of the column and are condensed.
This gives us a variety of shorted hydrocarbons which we can use for a number of different things, more useful than long hydrocarbon chains.
Reference:
https://getrevising.co.uk/resources/crude_oil_and_alkanes
This is the end of the topic! Well done!
Drafted by Cherry (Chemistry)