Crude oil
A thick dark liquid found underground, made from the remains of ancient sea creatures. It is a mixture of many hydrocarbons and is a non-renewable resource.
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Analogy
Crude oil is like a giant smoothie of fuels. It has to be separated before it is useful.
In practice
Petrol, diesel, jet fuel and the starting materials for plastics all come from crude oil.
Practice
Flashcards
- What does fractional distillation separate?Crude oil into fractions with different boiling points.
Interview questions
- Describe how fractional distillation separates crude oil and explain why the fractions come out at different heights.
- Oil is heated and vapours enter the column
- The column is hotter at the bottom and cooler at the top
- Molecules condense where the temperature is below their boiling point
- Smaller molecules with low boiling points rise higher
Questions people ask
Why is crude oil called a non-renewable resource?
It forms over millions of years from the remains of dead sea creatures buried under mud. We use it far faster than it forms, so once used it cannot be replaced in a human lifetime. This is why people look for renewable alternatives such as wind and solar.
What is crude oil used for apart from fuel?
Many products start from crude oil, including plastics, solvents, detergents, lubricants and bitumen for roads. A large share is burned as fuel, but some chemists argue oil is too valuable as a raw material to burn. Cracking turns oil fractions into ethene and propene for polymers.