Organic ChemistryTopic Summary
Knowledge Organiser: Crude Oil & Fractional Distillation
Part of Crude Oil · GCSE GCSE Chemistry revision
This topic summary covers Knowledge Organiser: Crude Oil & Fractional Distillation within Crude Oil for GCSE Chemistry. Topic 37: Crude Oil It is section 13 of 13 in this topic. Use this topic summary to connect the idea to the wider topic before moving on to questions and flashcards.
Topic position
Section 13 of 13
Practice
20 questions
Recall
0 flashcards
Knowledge Organiser: Crude Oil & Fractional Distillation
Key Terms
- Crude oil — mixture of hydrocarbons
- Hydrocarbon — contains C and H only
- Fraction — group with similar bp
- Fractional distillation — physical separation by bp
Column Position Rules
- Top = small, low bp, flammable, runny
- Bottom = large, high bp, less flammable, viscous
- Hot at bottom, cool at top
- Gases exit at the very top
Fractions (top to bottom)
- Refinery gases (C1-C4) — heating/fuel
- Petrol (C5-C10) — cars
- Kerosene — jet fuel
- Diesel — vehicles/heating
- Bitumen — roads
Exam Checklist
- Physical process — no bonds broken
- Smaller = lower bp = higher up column
- Crude oil = finite, non-renewable
- Separated by boiling points
Key Equations
- Alkanes general formula: CₙH₂ₙ₊₂
- Complete combustion: CₙH₂ₙ₊₂ + O₂ → CO₂ + H₂O
- Fractions separated by boiling point — no chemical reaction involved
Common Mistakes
- Saying fractional distillation is a chemical process: It is a PHYSICAL separation — no bonds are broken; hydrocarbons are not chemically changed
- Getting column position wrong: Small molecules (short chains) have LOW boiling points and rise to the TOP of the column — large molecules stay at the bottom
- Saying crude oil is renewable: Crude oil is a finite, non-renewable fossil fuel — it cannot be replaced on human timescales
- Confusing fractions and compounds: Each fraction is a MIXTURE of hydrocarbons with similar boiling points — not a single pure compound