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Organic Chemistry GCSE AQA Cheat Sheet (DRAFT) by

Cheatsheet for EOT test for Organic Chemistry.

This is a draft cheat sheet. It is a work in progress and is not finished yet.


Made out of only hydrogen and carbon.
Alkanes have the general formula HₙC₂ₙ₊₂.
Alkanes are homolo­gous- they react in a similar way.
Alkanes are saturated- they all have four covalent bonds.
The first four alkanes are methane, ethane, propene and butane.
These can be remembered by My Elephants Pooey Bum.
As the chains get shorter, the flamma­bility, volati­lity, and thickness decreases.
Short chain hydroc­arbons are more useful than longer ones.


Cracking is the breaking of long chain hydroc­arbons into small ones.
Cracking produces an alkane and an alkene.
Cracking is a thermal decomp­osition reaction.
Catalytic Cracking- You can pass long chain molecules over a hot powdered aluminium oxide catalyst.
Thermal Cracking- You can crack hydroc­arbons by vaporising them, mixing them with steam and heating them to a very high temper­ature.
What ever goes into a cracking reaction comes out.

Combustion of Hydroc­arbons

The complete combustion of any hydroc­arbon in oxygen releases a lot of energy.
Hydroc­arbon + Oxygen --> Carbon Dioxide + Water (+energy)
Both carbon and hydrogen are oxidised.
An equation must be balanced.

Crude Oil

Crude oil is a fossil fuels, formed over millions of years, with high temper­atures and pressure.
It is formed from plankton, and can be drilled up from rocks.
It is a non-re­newable and finite resource. They are being used up much faster than they are being formed.

Uses of Crude Oil

Oil is used for modern transport. This includes LPG, Heavy Fuel Oil, Diesel Oil and Kerosene.
All of the products from crude oil are organic compounds.

Fractional Distil­lation of Crude Oil

Crude oil is made out of hydroc­arbons, mostly alkanes.
The oil is heated until most of it turns not a gas. It enters the fracti­onating column.
There is a temper­ature gradient in the column. It is cooler at the top, and hotter at the bottom.
The shorter hydroc­arbons have the lowest boiling points and are condensed at the top.
You end up with LPG, Petrol, Kerosene, Diesel Oil, Heavy Fuel Oil, and Bitumen.
Little (shortest chain) Penguins Keep Drinking Hot Beer


Alkenes have a C=C Double Bond, meaning that alkenes have two fewer hydrogens compare to alkanes.
Alkenes are unsatu­rated.
Alkenes are more reactive than alkanes due to the double bond being able to make a single bond.
Ethene, Propene, Butene and Pentene.
The General Formula is: HₙC₂ₙ
To test for alkenes, you use bromine water, which turns from bright orange to colour­less.
Alkenes can be used to produce polymers and may other chemicals.