Crude Oil (Edexcel GCSE Chemistry: Combined Science)

Mixture of Hydrocarbons

• Crude oil is a complex mixture of lots of different hydrocarbon compounds of different sizes
• Hydrocarbons are compounds that contain hydrogen and carbon atoms only
• It is a thick, sticky, black liquid that is found in porous rock (under the ground and under the sea)

Diagram showing crude oil under the sea

Chains & Rings

• The hydrocarbon molecules in crude oil consist of a carbon backbone which can be in a ring or chain, with hydrogen atoms attached to the carbon atoms
• The mixture contains molecules with many different ring sizes and chain lengths

Crude oil is a mixture containing different sized hydrocarbon molecules

Useful Substances

• Crude oil is the main source of hydrocarbons which are used for producing fuels such as petrol and diesel.
• It is also a main source of raw materials (called feedstock) for the petrochemical industry

Finite Resource

• Crude oil formed over millions of years from the effects of high pressures and temperatures on the remains of plants and animals
• Since it is being used up much faster than it is being formed crude oil is a finite resource
• The petrochemical industry is hugely important for modern society and development
• The fuels that are used in most modern methods of transport (cars, trains, airplanes etc.) are all based on oil products
• Polymers, lubricants, solvents, detergents and adhesives are all products that are obtained from crude oil