ChemistryChapter 22: Energy
Fossil Fuels and Crude Oil
Crude oil is a mixture of hydrocarbons.
Learning objectives
- Explain fossil fuels and crude oil in simple chemical language.
- Connect 1. mixture with 2. fractions named using equations, observations, or trends where needed.
- Answer a short Federal Board question with the correct terms and a clear reason.
Definition
Crude oil is a mixture of hydrocarbons. Formation: ancient plankton/buried organic matter over geological time (school). Non-renewable on a human timescale. Fractional distillation named: heat, tower, fractions by b.p. (refinery stage name, not a plant design). Meaning: petrol, kerosene, diesel, lubricating oil, bitumen are cuts, not pure compounds. Coal, oil, gas — hydrocarbon stores from ancient biomass; finite on human timescale. Compare fuels on emissions and renewability, not slogans alone — one advantage and one drawback each.
Important terms
- FOSSIL FUELS AND CRUDE OIL
- Crude oil is a mixture of hydrocarbons.
- 1. MIXTURE
- Alkanes mainly, some other organics.
- 2. FRACTIONS NAMED
- Refinery gas, petrol, naphtha, kerosene, diesel, residue.
Relationship
- fraction = b.p. cut
Overview
What it is, then the tower names:
Mixture
Alkanes mainly, some other organics. Viscous black. Sour if sulphur (SO2 later when burned). Not a drilling manual. Crude fractionated by boiling range: gas, petrol, kerosene, diesel, residue.
Examples Short: gas · Middle: fuels · Long: bitumen
Fractions Named
Refinery gas, petrol, naphtha, kerosene, diesel, residue. Higher up the tower: lower b.p., smaller molecules, more volatile, lower viscosity (school table). Combustion releases stored chemical energy as heat — CO2 and pollutants follow.
Examples Top: gases · Bottom: bitumen · Not a P&ID
WHAT — FOSSIL FUELS AND CRUDE OIL
Crude oil is a mixture of hydrocarbons. Formation: ancient plankton/buried organic matter over geological time (school). Non-renewable on a human timescale. Fractional distillation named: heat, tower, fractions by b.p. (refinery stage name, not a plant design). Meaning: petrol, kerosene, diesel, lubricating oil, bitumen are cuts, not pure compounds. Coal, oil, gas — hydrocarbon stores from ancient biomass; finite on human timescale. Compare fuels on emissions and renewability, not slogans alone — one advantage and one drawback each.
WHY — Why this topic matters
FOSSIL FUELS AND CRUDE OIL is an independent FBISE learning unit because students must use its definitions, conditions, equations, or trends separately in explanations and calculations.
HOW — How it works
MIXTURE: Alkanes mainly, some other organics. Viscous black. Sour if sulphur (SO2 later when burned). Not a drilling manual. Crude fractionated by boiling range: gas, petrol, kerosene, diesel, residue. Examples: Short: gas; Middle: fuels; Long: bitumen. FRACTIONS NAMED: Refinery gas, petrol, naphtha, kerosene, diesel, residue. Higher up the tower: lower b.p., smaller molecules, more volatile, lower viscosity (school table). Combustion releases stored chemical energy as heat — CO2 and pollutants follow. Examples: Top: gases; Bottom: bitumen; Not a P&ID. Exam fractional distillation: crude oil is a mixture tower separates by boiling point smaller molecules higher up (named fractions)
In simple words
Named fractions. No refinery design or drilling how-to.
Key points
- mixture of hydrocarbons
- fraction = b.p. cut
- many chain lengths
- b.p. up with size
Exam preparation
Exam Focus
Quick revision
Revision Zone
Review the key facts, formulas and checks before you move on.Fossil Fuels and Crude Oil
Sticky Notes · Quick Revision
Core Idea
- Crude oil is a mixture of hydrocarbons. Formation: ancient plankton/buried organic matter over geological time (school). Non-renewable on a human timescale. Fractional distillation named: heat, tower, fractions by b.p. (refinery stage name, not a plant design). Meaning: petrol, kerosene, diesel, lubricating oil, bitumen are cuts, not pure compounds. Coal, oil, gas — hydrocarbon stores from ancient biomass; finite on human timescale. Compare fuels on emissions and renewability, not slogans alone — one advantage and one drawback each.
1. MIXTURE
- Alkanes mainly, some other organics. Viscous black. Sour if sulphur (SO2 later when burned). Not a drilling manual. Crude fractionated by boiling range: gas, petrol, kerosene, diesel, residue.
- Short: gas
- Middle: fuels
- Long: bitumen
2. FRACTIONS NAMED
- Refinery gas, petrol, naphtha, kerosene, diesel, residue. Higher up the tower: lower b.p., smaller molecules, more volatile, lower viscosity (school table). Combustion releases stored chemical energy as heat — CO2 and pollutants follow.
- Top: gases
- Bottom: bitumen
- Not a P&ID
Exam Example
- Exam fractional distillation:
- crude oil is a mixture
- tower separates by boiling point
- smaller molecules higher up (named fractions)
Common Misconceptions
- Do not confuse 1. MIXTURE with 2. FRACTIONS NAMED; state the difference before giving an example.
- Writing only “mixture of hydrocarbons” is not enough. Explain what it means in a complete sentence.
FBISE Exam Check
- Explain fossil fuels and crude oil, compare its two main parts, and include the correct chemical evidence.
- Named fractions. No refinery design or drilling how-to.
60-second revision
- Crude oil is a mixture of hydrocarbons.
- 1. MIXTURE: Alkanes mainly, some other organics.
- 2. FRACTIONS NAMED: Refinery gas, petrol, naphtha, kerosene, diesel, residue.
- Exam reminder: Exam fractional distillation: crude oil is a mixture tower separates by boiling point smaller molecules higher up (named fractions)
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