5.2.1
Fractional Distillation
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Fractional Distillation
Fractional distillation is the process of separating crude oil into groups of hydrocarbons with similar numbers of carbon atoms. We call these groups of hydrocarbons “fractions”.

Long-chain hydrocarbons
- Hydrocarbons with lots of carbon atoms are called ‘long-chain hydrocarbons’.

Short-chain hydrocarbons
- Hydrocarbons with few carbon atoms are called 'short-chain hydrocarbons'.
The Process of Fractional Distillation
Different-sized hydrocarbons have different boiling points. Fractional distillation separates hydrocarbons using their different boiling points. The steps of the process are:

Evaporation
- Crude oil is heated until it evaporates.
- Crude oil vapour is put into a fractionating column at the bottom and rises upwards.

Condensation
- The temperature is highest at the bottom of the column. Long-chain hydrocarbons condense at the bottom and are collected as liquids.
- Short-chain hydrocarbons have lower boiling points. They pass up the column and condense at lower temperatures nearer the top.

Collection
- The fractions are collected. They are then processed to create end products:
- Fuels (e.g. petrol, diesel) are a common end product.
- The petrochemical industry can use some fractions as feedstock (material used in an industrial process) to make solvents, lubricants, detergents etc.
1Physical Chemistry
1.1Atomic Structure
1.1.1Fundamental Particles1.1.2Isotopes & Mass Number1.1.3Mass Spectrometry1.1.4Electron Shells, Sub-Shells & Orbitals1.1.5Electron Configuration1.1.6Ionisation Energy1.1.7Factors Affecting Ionisation Energies1.1.8Trends of Ionisation1.1.9Specific Impacts on Ionisation Energies1.1.10End of Topic Test - Atomic Structure1.1.11A-A* (AO3/4) - Atomic Structure
1.2Amount of Substance
1.2.1Relative Masses1.2.2The Mole1.2.3The Ideal Gas Equation1.2.4Empirical & Molecular Formulae1.2.5Balanced Equations1.2.6Percentage Yield1.2.7A-A* (AO3/4) - Percentage Yield1.2.8Atom Economy1.2.9End of Topic Test - Amount of Substance1.2.10A-A* (AO3/4) - Substances & Yield1.2.11Diagnostic Misconceptions - Moles
1.3Bonding
1.3.1Ionic Bonding1.3.2Covalent & Dative Bonding1.3.3Carbon Structures1.3.4Metallic Bonding1.3.5Physical Properties1.3.6Shapes of Molecules1.3.7Polarity1.3.8Intermolecular Forces1.3.9Intermolecular Forces 21.3.10End of Topic Test - Bonding1.3.11Exam-Style Question - Shape of Molecules1.3.12A-A* (AO3/4) - Bonding1.3.13Diagnostic Misconceptions - Ions1.3.14Diagnostic Misconceptions - Ionic & Covalent1.3.15Diagnostic Misconceptions - Phase Change1.3.16Diagnostic Misconceptions - Boiling1.3.17Diagnostic Misconceptions - Polar Bonds
1.4Energetics
1.5Kinetics
1.6Equilibria
2Physical Chemistry 2 (A2 Only)
2.1Thermodynamics (A2 Only)
2.2Rate Equations (A2 Only)
2.3The Equilibrium Constant Kp (A2 Only)
2.4Electrochemical Cells (A2 Only)
2.5Acids & Bases (A2 Only)
2.5.1Brønsted-Lowry Acids & Bases (A2 Only)2.5.2pH (A2 Only)2.5.3The Ionic Product of Water (A2 Only)2.5.4Weak Acids & Bases (A2 Only)2.5.5pH Curves & Titrations (A2 Only)2.5.6pH Curves & Titrations 2 (A2 Only)2.5.7Buffer Solutions (A2 Only)2.5.8End of Topic Test - Acids & Bases2.5.9Exam-Style Question - Weak Acids2.5.10A-A* (AO3/4) - Acids & Bases2.5.11Diagnostic Misconceptions - Ammonia is an Alkali2.5.12Diagnostic Misconceptions - Water's Neutrality2.5.13Diagnostic Misconceptions - Concentrate & Strength
3Inorganic Chemistry
3.1Periodicity & Trends
4Inorganic Chemistry 2 (A2 Only)
4.1Period 3 (A2 Only)
4.2Transition Metals (A2 Only)
4.2.1General Properties (A2 Only)4.2.2Substitution Reactions (A2 Only)4.2.3Shapes of Complex Ions (A2 Only)4.2.4Colours of Ions (A2 Only)4.2.5Variable Oxidation States (A2 Only)4.2.6Titrations (A2 Only)4.2.7Homogeneous Catalysts (A2 Only)4.2.8Heterogeneous Catalysts (A2 Only)4.2.9End of Topic Test - Transition Metals4.2.10A-A* (AO3/4) - Transition Metals
4.3Reactions of Ions in Aqueous Solutions (A2 Only)
5Organic Chemistry 1
5.1Introduction
5.2Alkanes
5.3Halogenoalkanes
5.4Alkenes
5.5Alcohols
5.6Organic Analysis
5.7A-A* (AO3/4) - Organic 1
6Organic Chemistry 2 (A2 Only)
6.1Optical Isomerism (A2 Only)
6.2Aldehydes & Ketones (A2 Only)
6.3Carboxylic Acids & Esters (A2 Only)
6.4Aromatic Chemistry (A2 Only)
6.5Amines (A2 Only)
6.6Polymers (A2 Only)
6.7Biological Organic (A2 Only)
6.8Organic Synthesis (A2 Only)
6.9NMR Spectroscopy (A2 Only)
6.10Chromatography (A2 Only)
6.11A-A* (AO3/4) - Organic 2
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1Physical Chemistry
1.1Atomic Structure
1.1.1Fundamental Particles1.1.2Isotopes & Mass Number1.1.3Mass Spectrometry1.1.4Electron Shells, Sub-Shells & Orbitals1.1.5Electron Configuration1.1.6Ionisation Energy1.1.7Factors Affecting Ionisation Energies1.1.8Trends of Ionisation1.1.9Specific Impacts on Ionisation Energies1.1.10End of Topic Test - Atomic Structure1.1.11A-A* (AO3/4) - Atomic Structure
1.2Amount of Substance
1.2.1Relative Masses1.2.2The Mole1.2.3The Ideal Gas Equation1.2.4Empirical & Molecular Formulae1.2.5Balanced Equations1.2.6Percentage Yield1.2.7A-A* (AO3/4) - Percentage Yield1.2.8Atom Economy1.2.9End of Topic Test - Amount of Substance1.2.10A-A* (AO3/4) - Substances & Yield1.2.11Diagnostic Misconceptions - Moles
1.3Bonding
1.3.1Ionic Bonding1.3.2Covalent & Dative Bonding1.3.3Carbon Structures1.3.4Metallic Bonding1.3.5Physical Properties1.3.6Shapes of Molecules1.3.7Polarity1.3.8Intermolecular Forces1.3.9Intermolecular Forces 21.3.10End of Topic Test - Bonding1.3.11Exam-Style Question - Shape of Molecules1.3.12A-A* (AO3/4) - Bonding1.3.13Diagnostic Misconceptions - Ions1.3.14Diagnostic Misconceptions - Ionic & Covalent1.3.15Diagnostic Misconceptions - Phase Change1.3.16Diagnostic Misconceptions - Boiling1.3.17Diagnostic Misconceptions - Polar Bonds
1.4Energetics
1.5Kinetics
1.6Equilibria
2Physical Chemistry 2 (A2 Only)
2.1Thermodynamics (A2 Only)
2.2Rate Equations (A2 Only)
2.3The Equilibrium Constant Kp (A2 Only)
2.4Electrochemical Cells (A2 Only)
2.5Acids & Bases (A2 Only)
2.5.1Brønsted-Lowry Acids & Bases (A2 Only)2.5.2pH (A2 Only)2.5.3The Ionic Product of Water (A2 Only)2.5.4Weak Acids & Bases (A2 Only)2.5.5pH Curves & Titrations (A2 Only)2.5.6pH Curves & Titrations 2 (A2 Only)2.5.7Buffer Solutions (A2 Only)2.5.8End of Topic Test - Acids & Bases2.5.9Exam-Style Question - Weak Acids2.5.10A-A* (AO3/4) - Acids & Bases2.5.11Diagnostic Misconceptions - Ammonia is an Alkali2.5.12Diagnostic Misconceptions - Water's Neutrality2.5.13Diagnostic Misconceptions - Concentrate & Strength
3Inorganic Chemistry
3.1Periodicity & Trends
4Inorganic Chemistry 2 (A2 Only)
4.1Period 3 (A2 Only)
4.2Transition Metals (A2 Only)
4.2.1General Properties (A2 Only)4.2.2Substitution Reactions (A2 Only)4.2.3Shapes of Complex Ions (A2 Only)4.2.4Colours of Ions (A2 Only)4.2.5Variable Oxidation States (A2 Only)4.2.6Titrations (A2 Only)4.2.7Homogeneous Catalysts (A2 Only)4.2.8Heterogeneous Catalysts (A2 Only)4.2.9End of Topic Test - Transition Metals4.2.10A-A* (AO3/4) - Transition Metals
4.3Reactions of Ions in Aqueous Solutions (A2 Only)
5Organic Chemistry 1
5.1Introduction
5.2Alkanes
5.3Halogenoalkanes
5.4Alkenes
5.5Alcohols
5.6Organic Analysis
5.7A-A* (AO3/4) - Organic 1
6Organic Chemistry 2 (A2 Only)
6.1Optical Isomerism (A2 Only)
6.2Aldehydes & Ketones (A2 Only)
6.3Carboxylic Acids & Esters (A2 Only)
6.4Aromatic Chemistry (A2 Only)
6.5Amines (A2 Only)
6.6Polymers (A2 Only)
6.7Biological Organic (A2 Only)
6.8Organic Synthesis (A2 Only)
6.9NMR Spectroscopy (A2 Only)
6.10Chromatography (A2 Only)
6.11A-A* (AO3/4) - Organic 2
Practice questions on Fractional Distillation
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- 3Which is NOT an end product of fractional distillation?Multiple choice
- 4What are these changes of state?Fill in the list
- 5What are the steps in the process of fractional distillation?Fill in the list
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