Key learning points

1. Fractions of crude oil have different properties and uses, affecting the demand for these molecules.
2. Larger hydrocarbons can be broken down (cracked) to produce smaller, more useful molecules.
3. Cracking can be done by various methods including catalytic cracking and steam cracking.
4. The products of cracking include alkanes and alkenes, which have a double bond between two carbon atoms.
5. Bromine water changes from orange/brown to colourless in the presence of an alkene.

Keywords

• Cracking - Cracking is a thermal decomposition reaction where larger alkanes are broken down into smaller alkanes and alkenes.

• Thermal decomposition - A thermal decomposition reaction is a type of reaction that uses heat to break down a reactant compound into two or more products.

• Catalyst - A catalyst is a chemical that speeds up the rate of a reaction without itself being used up.

• Saturated - Alkanes are saturated hydrocarbons as they contain only single bonds between carbon atoms.

• Unsaturated - Unsaturated compounds contain at least one carbon-carbon double covalent bond.

Common misconception