Petroleum and Fractional Distillation
Crude oil is separated by boiling point into fuels.
About this topic
Petroleum, or crude oil, is a mixture of hydrocarbons formed from ancient marine organisms over millions of years. Fractional distillation separates it into fractions according to boiling point in a tall fractionating column that is hot at the bottom and cooler at the top. Small molecules with low boiling points rise to the top; large ones stay at the bottom.
Crude oil is heated to vaporise it and fed into the column. As vapours rise, each condenses at the level where the temperature is below its boiling point. The fractions, from top to bottom, are refinery gases (LPG), petrol (gasoline), naphtha, kerosene (jet fuel), diesel, fuel oil and bitumen. Longer chains are more viscous, less flammable and darker. Cracking breaks large hydrocarbons into smaller, more useful alkanes and alkenes by heat and a catalyst, to meet demand for petrol and to produce monomers: C10H22 gives C8H18 + C2H4. Reforming improves petrol quality.
Petroleum provides fuels, plastics, lubricants, solvents, fertilisers, medicines and asphalt for roads. But burning it releases carbon dioxide, a greenhouse gas, and spills damage ecosystems, so alternatives are needed.
A misconception is that distillation chemically changes the oil; fractional distillation is a physical separation, whereas cracking is chemical. Another is that oil comes from dinosaurs, when it mainly came from plankton and algae.
Key ideas
- Fractions: gas, petrol, diesel, bitumen
- Heavier fractions boil higher
- Cracking breaks big molecules
Quick check
Use cases: where Petroleum and Fractional Distillation helps
- Homework: review the key idea behind Petroleum and Fractional Distillation before you start a problem set.
- Exam revision: use the quick check to test whether you can recall Petroleum and Fractional Distillation without notes.
- Visual learning: play with the interactive lab to see how Petroleum and Fractional Distillation changes when you adjust its inputs.
- Teaching a friend: explain Petroleum and Fractional Distillation in your own words, then compare your version with the key ideas.
Chemistry explains medicine, food, cleaning products, fuels and building materials.
Frequently asked questions
What is Petroleum and Fractional Distillation?
Crude oil is separated by boiling point into fuels.
What will I learn in Petroleum and Fractional Distillation?
Fractions: gas, petrol, diesel, bitumen. Heavier fractions boil higher. Cracking breaks big molecules.
Is Petroleum and Fractional Distillation part of Chemistry?
Yes. It is one of 150 Chemistry topics on LearnViz HighSchoolEdu, with 3 key ideas, a live animation and a quick check.
Does the Petroleum and Fractional Distillation lab work on a phone or tablet?
Yes. The animation resizes to fit your screen and supports touch, so you can drag, tap and slide with your finger.
How should I study Petroleum and Fractional Distillation?
Read the summary and key ideas first, play with the interactive lab to see the idea in motion, then answer the quick check. If you get a question wrong, go back to the key idea it tests.
Do I need an account, and is my progress saved?
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