Fractional distillation is the key process that turns crude oil...
Chemistry649 views·Updated 22 Jun 2026·2 pagesUnderstanding Fractional Distillation
L
lydia wilton@lydiawilton_deay
1
of 2
How Fractional Distillation Works
Ever wondered how we get petrol for cars from thick black crude oil? It's all about fractional distillation! This process splits crude oil into useful products by heating it and separating the components.
The process begins by heating crude oil to high temperatures (around 350°C). When heated, different parts of the crude oil turn into vapours at different temperatures. The shorter chain hydrocarbons (like those in petrol) have lower boiling points, so they vapourise first and rise to the top of the fractionating column.
Meanwhile, the longer chain hydrocarbons (like those in diesel and bitumen) have higher boiling points. They vapourise last and stay near the bottom of the column. As the vapours rise through the column, they cool and condense at different heights depending on their boiling points.
Remember this: Temperature decreases as you move up the fractionating column! The top is cool (about 25°C) while the bottom remains hot (around 350°C).
The whole process works because different hydrocarbons have different properties. Those with fewer carbon atoms require less energy to boil, while those with more carbon atoms need more energy to break their stronger bonds.
2
of 2
Fractions and Their Uses
The different parts we get from crude oil are called fractions - they're only portions of the original oil but much more useful! Each fraction has unique properties that make it perfect for specific uses.
Small hydrocarbon molecules (like those in gas and petrol) have weak forces holding them together, giving them low boiling points. These are highly volatile substances that flow easily and ignite quickly - perfect for fuels! The largest molecules form bitumen, which hardly flows at all and is difficult to ignite.
The main fractions we get include liquefied petroleum gas (LPG) for heating and cooking, petrol for cars, kerosene for aircraft, diesel for cars and trains, heavy fuel oil for ships and power stations, and bitumen for roads and roofs.
Quick tip: Try this memory aid for the fractions from top to bottom: "Lazy Penguins Keep Drinking Hot Beer" for LPG, Petrol, Kerosene, Diesel, Heavy fuel oil, and Bitumen!
The properties of each fraction directly relate to their uses. Petrol needs to ignite easily in car engines, while bitumen needs to be solid and waterproof for road surfaces. This is why separating crude oil is so important - it gives us exactly what we need for different purposes.
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Chemistry649 views·Updated 22 Jun 2026·2 pagesUnderstanding Fractional Distillation
L
lydia wilton@lydiawilton_deay
Fractional distillation is the key process that turns crude oil into the useful products we use every day. This process separates crude oil into different fractions based on their boiling points, giving us everything from petrol for cars to bitumen...
1
of 2
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How Fractional Distillation Works
Ever wondered how we get petrol for cars from thick black crude oil? It's all about fractional distillation! This process splits crude oil into useful products by heating it and separating the components.
The process begins by heating crude oil to high temperatures (around 350°C). When heated, different parts of the crude oil turn into vapours at different temperatures. The shorter chain hydrocarbons (like those in petrol) have lower boiling points, so they vapourise first and rise to the top of the fractionating column.
Meanwhile, the longer chain hydrocarbons (like those in diesel and bitumen) have higher boiling points. They vapourise last and stay near the bottom of the column. As the vapours rise through the column, they cool and condense at different heights depending on their boiling points.
Remember this: Temperature decreases as you move up the fractionating column! The top is cool (about 25°C) while the bottom remains hot (around 350°C).
The whole process works because different hydrocarbons have different properties. Those with fewer carbon atoms require less energy to boil, while those with more carbon atoms need more energy to break their stronger bonds.
2
of 2Sign up to see the content. It's free!
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By signing up you accept Terms of Service and Privacy Policy
Fractions and Their Uses
The different parts we get from crude oil are called fractions - they're only portions of the original oil but much more useful! Each fraction has unique properties that make it perfect for specific uses.
Small hydrocarbon molecules (like those in gas and petrol) have weak forces holding them together, giving them low boiling points. These are highly volatile substances that flow easily and ignite quickly - perfect for fuels! The largest molecules form bitumen, which hardly flows at all and is difficult to ignite.
The main fractions we get include liquefied petroleum gas (LPG) for heating and cooking, petrol for cars, kerosene for aircraft, diesel for cars and trains, heavy fuel oil for ships and power stations, and bitumen for roads and roofs.
Quick tip: Try this memory aid for the fractions from top to bottom: "Lazy Penguins Keep Drinking Hot Beer" for LPG, Petrol, Kerosene, Diesel, Heavy fuel oil, and Bitumen!
The properties of each fraction directly relate to their uses. Petrol needs to ignite easily in car engines, while bitumen needs to be solid and waterproof for road surfaces. This is why separating crude oil is so important - it gives us exactly what we need for different purposes.
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Students love us — and so will you.
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