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

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

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

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

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

Cracking fractions of crude oil

Combined science

In the Atmosphere and Changing Climate unit, pupils will build on their understanding of Earth's resources to learn about the evidence for the composition and evolution of the Earth's atmosphere and the impact of human activity on climate change.

In the Earth's Resources unit, pupils learned about the composition and structure of the Earth, and the rock cycle.

Using Earth's resources

Which of the following fractions are commonly used as fuels for cars?

What is the name of the thermal decomposition reaction where larger alkanes are broken down into smaller alkanes and alkenes?

Which of the following is an example of a hydrocarbon that can be cracked?

Which process involves heating larger alkanes to vapourise them, mixing with steam and heating to high temperatures to break down the hydrocarbon molecules? 

They have a double bond between carbon atoms.

Bromine water remains an orange/brown colour when an alkene is added.

Which of the following statements about alkenes is false?

They have the same boiling points but different densities.

They have different boiling points, viscosities, and flammabilities.

They have the same chemical structure but different colours.

Which statement best describes why different fractions of crude oil have different properties and uses?

Which property of hydrocarbons affects their viscosity?

In the fractional distillation of crude oil, which fraction is collected at the bottom of the column?

Alkanes contain single bonds between carbon atoms.

Alkanes contain double bonds between carbon atoms.

Which of the following statements about alkanes are true?

Which of the following hydrocarbons is the most flammable?

A process to separate a mixture of solids based on their densities.

A technique to separate a mixture of liquids based on their boiling points.

A method to combine different liquids into a single mixture.

A process to break down large alkanes into smaller more useful molecules.

Why do smaller hydrocarbon molecules have lower boiling points?

This lesson will be removed by end of Summer Term 2025.

Cracking fractions of crude oil

Lesson outcome

This lesson will be removed by end of Summer Term 2025.