Save My Exams Logo
  • GCSE
  • IGCSE
  • AS
  • A Level
  • O Level
  • Pre U
  • IB
  • Login
  •  
MathsBiologyChemistryPhysicsCombined ScienceEnglish LanguageOther Subjects
GCSE > Maths
Edexcel Topic QuestionsRevision NotesPast PapersPast Papers (old spec)
AQA Topic QuestionsRevision NotesPast Papers
OCR Topic QuestionsRevision NotesPast Papers
GCSE > Biology
Edexcel Topic QuestionsRevision NotesPast Papers
AQA Topic QuestionsRevision NotesPast Papers
OCR Gateway Topic QuestionsRevision NotesPast Papers
GCSE > Chemistry
Edexcel Topic QuestionsRevision NotesPast Papers
AQA Topic QuestionsRevision NotesPast Papers
OCR Gateway Topic QuestionsRevision NotesPast Papers
GCSE > Physics
Edexcel Topic QuestionsRevision NotesPast Papers
AQA Topic QuestionsRevision NotesPast Papers
OCR Gateway Topic QuestionsRevision NotesPast Papers
GCSE > Combined Science
Edexcel Combined: Biology Revision NotesPast Papers
Edexcel Combined: Chemistry Revision NotesPast Papers
Edexcel Combined: Physics Revision NotesPast Papers
AQA Combined: Biology Topic QuestionsRevision NotesPast Papers
AQA Combined: Chemistry Topic QuestionsRevision NotesPast Papers
AQA Combined: Physics Topic QuestionsRevision NotesPast Papers
OCR Gateway Combined: Biology Topic QuestionsRevision Notes
OCR Gateway Combined: Physics Revision Notes
GCSE > English Language
AQA Revision NotesPractice PapersPast Papers
Edexcel Past Papers
OCR Past Papers
GCSE > Other Subjects
AQA English LiteratureBusiness StudiesComputer ScienceEconomicsFurther MathsGeographyHistoryPsychologySociologyStatistics
Edexcel English LiteratureBusiness StudiesComputer ScienceGeographyHistoryPsychologyStatistics
OCR English LiteratureBusiness StudiesComputer ScienceEconomicsPsychology
OCR Gateway GeographyHistory
MathsBiologyChemistryPhysicsDouble ScienceEnglish LanguageGeographyOther Subjects
IGCSE > Maths
Edexcel Topic QuestionsRevision NotesPast PapersBronze-Silver-Gold Questions
CIE (Extended) Topic QuestionsRevision NotesPast Papers
CIE (Core) Topic QuestionsPast Papers
IGCSE > Biology
Edexcel Topic QuestionsRevision NotesPast Papers
CIE Topic QuestionsRevision NotesPast Papers
IGCSE > Chemistry
Edexcel Topic QuestionsRevision NotesPast Papers
CIE Topic QuestionsRevision NotesPast Papers
IGCSE > Physics
Edexcel Topic QuestionsRevision NotesPast Papers
CIE Topic QuestionsRevision NotesPast Papers
IGCSE > Double Science
Edexcel Double: Biology Topic QuestionsRevision NotesPast Papers
Edexcel Double: Chemistry Topic QuestionsRevision NotesPast Papers
Edexcel Double: Physics Topic QuestionsRevision NotesPast Papers
IGCSE > English Language
CIE Revision NotesPractice PapersPast Papers
Edexcel Past Papers
IGCSE > Geography
CIE Past Papers
Edexcel Revision NotesPast Papers Topic QuestionsPast Papers
IGCSE > Other Subjects
CIE Additional MathsEnglish LiteratureBusinessComputer ScienceEconomicsHistorySociology
Edexcel English LiteratureBusinessComputer ScienceHistoryFurther Maths
MathsBiologyChemistryPhysicsEnglish LanguageOther Subjects
AS > Maths
Edexcel Pure MathsMechanicsStatistics
AQA Pure MathsMechanicsStatistics
OCR Pure MathsMechanicsStatistics
CIE Pure 1Pure 2MechanicsProbability & Statistics 1
Edexcel IAS Pure 1Pure 2MechanicsStatistics
AS > Biology
AQA Topic QuestionsRevision NotesPast Papers
OCR Revision NotesPast Papers
CIE 2019-2021 Topic QuestionsRevision NotesPast Papers
CIE 2022-2024 Topic QuestionsRevision NotesPast Papers
Edexcel IAL Revision Notes
AS > Chemistry
Edexcel Revision Notes
AQA Topic QuestionsRevision NotesPast Papers
OCR Revision Notes
CIE 2019-2021 Topic QuestionsRevision NotesPast Papers
CIE 2022-2024 Topic QuestionsRevision NotesPast Papers
Edexcel IAL Revision Notes
AS > Physics
Edexcel Revision Notes
AQA Topic QuestionsRevision NotesPast Papers
OCR Revision NotesPast Papers
CIE 2019-2021 Topic QuestionsRevision NotesPast Papers
CIE 2022-2024 Topic QuestionsRevision NotesPast Papers
Edexcel IAL Revision Notes
AS > English Language
AQA Past Papers
Edexcel Past Papers
OCR Past Papers
AS > Other Subjects
AQA Business StudiesComputer ScienceEconomicsEnglish LiteratureFurther MathsGeographyHistoryPsychologySociology
Edexcel Business StudiesEconomicsEnglish LiteratureFurther MathsGeographyHistoryPsychology
OCR Business StudiesComputer ScienceEconomicsEnglish LiteratureFurther Maths AGeographyHistoryPsychologySociology
CIE Further Maths
MathsBiologyChemistryPhysicsEnglish LanguageEconomicsPsychologyOther Subjects
A Level > Maths
Edexcel Pure MathsMechanicsStatistics
AQA Pure MathsMechanicsStatistics
OCR Pure MathsMechanicsStatistics
CIE Pure 1Pure 3MechanicsProbability & Statistics 1Probability & Statistics 2
Edexcel IAL Pure 1Pure 2Pure 3Pure 4Mechanics 1Mechanics 2Statistics 1Statistics 2
A Level > Biology
Edexcel Topic QuestionsPast Papers
Edexcel A (SNAB) Revision Notes
AQA Topic QuestionsRevision NotesPast Papers
OCR Topic QuestionsRevision NotesPast PapersGold Questions
CIE 2019-2021 Topic QuestionsRevision NotesPast Papers
CIE 2022-2024 Topic QuestionsRevision NotesPast Papers
Edexcel IAL Topic QuestionsRevision NotesPast Papers
A Level > Chemistry
Edexcel Topic QuestionsRevision NotesPast Papers
AQA Topic QuestionsRevision NotesPast Papers
OCR Topic QuestionsRevision NotesPast PapersGold Questions
CIE 2019-2021 Topic QuestionsRevision NotesPast Papers
CIE 2022-2024 Topic QuestionsRevision NotesPast Papers
Edexcel IAL Topic QuestionsRevision NotesPast Papers
A Level > Physics
Edexcel Topic QuestionsRevision NotesPast Papers
AQA Topic QuestionsRevision NotesPast Papers
OCR Topic QuestionsRevision NotesPast Papers
CIE 2019-2021 Topic QuestionsRevision NotesPast Papers
CIE 2022-2024 Topic QuestionsRevision NotesPast Papers
Edexcel IAL Topic QuestionsRevision NotesPast Papers
A Level > English Language
AQA Past Papers
CIE Past Papers
Edexcel Past Papers
OCR Past Papers
Edexcel IAL Past Papers
A Level > Economics
Edexcel Past PapersPast Papers Topic QuestionsRevision Notes
AQA Past PapersPast Papers Topic Questions
OCR Past Papers
CIE Past Papers
A Level > Psychology
AQA Past Papers Topic QuestionsPast PapersRevision Notes
CIE Past Papers
Edexcel Past Papers
OCR Past Papers
Edexcel IAL Past Papers
A Level > Other Subjects
AQA Business StudiesComputer ScienceEconomicsEnglish LiteratureFurther MathsGeographyHistorySociology
CIE BusinessComputer ScienceEconomicsEnglish LiteratureFurther MathsGeographySociology
Edexcel Business StudiesEconomics AEnglish LiteratureFurther MathsGeographyHistory
OCR Business StudiesComputer ScienceEconomicsEnglish LiteratureFurther Maths AGeographyHistorySociology
Edexcel IAL English LiteratureGeography
CIE IAL History
BiologyChemistryPhysicsOther Subjects
O Level > Biology
CIE Topic QuestionsPast Papers
O Level > Chemistry
CIE Topic QuestionsPast Papers
O Level > Physics
CIE Topic QuestionsPast Papers
O Level > Other Subjects
CIE Additional MathsMaths D
MathsBiologyChemistryPhysics
Pre U > Maths
CIE Topic QuestionsPast Papers
Pre U > Biology
CIE Topic QuestionsPast Papers
Pre U > Chemistry
CIE Topic QuestionsPast Papers
Pre U > Physics
CIE Topic QuestionsPast Papers
MathsBiologyChemistryPhysics
IB > Maths
Maths: AA HL Topic QuestionsRevision Notes
Maths: AI HL Topic QuestionsRevision Notes
Maths: AA SL Topic QuestionsRevision NotesPractice Papers
Maths: AI SL Topic QuestionsRevision NotesPractice Papers
IB > Biology
Biology: SL Topic QuestionsRevision Notes
Biology: HL Topic QuestionsRevision Notes
IB > Chemistry
Chemistry: SL Topic QuestionsRevision Notes
Chemistry: HL Topic QuestionsRevision Notes
IB > Physics
Physics: SL Topic QuestionsRevision Notes
Physics: HL Topic QuestionsRevision Notes

OCR Gateway GCSE Chemistry

Revision Notes

Home / GCSE / Chemistry / OCR Gateway / Revision Notes / 6.1 Global Challenges / 6.2 Organic chemistry / 6.2.9 Cracking


6.2.9 Cracking


Cracking

  • Saturated molecules contain single bonds only whereas unsaturated molecules contain double bonds between their carbon atoms
  • Alkanes are saturated compounds and alkenes are unsaturated compounds
  • Long chain alkane molecules are further processed to produce other products consisting of smaller chain molecules
  • A process called cracking is used to convert them into short chain molecules which are more useful
  • Small alkenes and hydrogen are produced using this process
  • Kerosene and diesel oil are often cracked to produce petrol, other alkenes and hydrogen

Cracking-Decane, IGCSE & GCSE Chemistry revision notes

Decane is cracked to produce octane for petrol and ethene for ethanol synthesis

  • Cracking involves heating the hydrocarbon molecules to around 600 – 700°C to vaporise them
  • The vapours then pass over a hot powdered catalyst of alumina or silica
  • This process breaks covalent bonds in the molecules as they come into contact with the surface of the catalyst, causing thermal decomposition reactions
  • The molecules are broken up in a random way which produces a mixture of smaller alkanes and alkenes
  • Hydrogen and a higher proportion of alkenes are formed at higher temperatures and higher pressure

Writing Equations for Cracking

  • We can use the general formulae for alkanes and alkenes to check that we have correctly balanced equations for cracking
  • Hexane for example, can be cracked to form butane and ethene, both of which are very useful molecules
  • Ethene as the starting material for the production of alcohol and butane is used as a fuel
  • The equation for this cracking reaction is:

C6H14 ⟶ C4H10 + C2H4

  • Note that the starting compound for this reaction is an alkane and thus the general formula CnH2n+2 applies
  • Butane is also an alkane and so the same rule applies
  • Ethene is an alkene and so its formula will follow the C2H2n rule

Exam Tip

Always check that sum of the carbons and hydrogens adds up on each side of the equation AND that you have made alkanes or alkenes.



  • 1. Particles
    • 1.1 The Particle Model
      • 1.1.1 The Particle Model
        • 1.1.2 Limitations of the Particle Model
        • 1.2 Atomic Structure
          • 1.2.1 Atomic Models Through Time
            • 1.2.2 Atomic Structure
              • 1.2.3 Calculating the Particles
            • 2. Elements, compounds & mixtures
              • 2.1 Purity & Separating Mixtures
                • 2.1.1 Pure & Impure
                  • 2.1.2 Relative Masses
                    • 2.1.3 Empirical Formula
                      • 2.1.4 Alloys
                        • 2.1.5 Separation Techniques
                          • 2.1.6 Chromatography
                          • 2.2 Bonding
                            • 2.2.1 Metals & Non-Metals
                              • 2.2.2 Electronic Structure
                                • 2.2.3 Ionic Bonding
                                  • 2.2.4 Covalent Bonding
                                    • 2.2.5 Giant Covalent Structures
                                      • 2.2.6 Polymers
                                        • 2.2.7 Metals
                                          • 2.2.8 Atomic Structure & the Periodic Table
                                          • 2.3 Properties of materials
                                            • 2.3.1 Carbon
                                              • 2.3.2 Changes of State
                                                • 2.3.3 Bulk Properties
                                                  • 2.3.4 Nanoparticles
                                                • 3. Chemical Reactions
                                                  • 3.1 Introducing Chemical Reactions
                                                    • 3.1.1 Chemical Symbols & Formulae
                                                      • 3.1.2 Deducing Formulae Using Common Ions
                                                        • 3.1.3 Balancing Chemical Equations
                                                          • 3.1.4 Writing Balanced Ionic Equations
                                                            • 3.1.6 Conservation of Mass
                                                              • 3.1.7 Using Moles to Balance Equations
                                                                • 3.1.8 Calculating Masses from Balanced Equations
                                                                • 3.2 Energetics
                                                                  • 3.2.1 Exothermic & Endothermic Reactions
                                                                    • 3.2.2 Calculating Energy Changes
                                                                    • 3.3 Types of Chemical Reactions
                                                                      • 3.3.1 Oxidation & Reduction
                                                                        • 3.3.2 OxidatIon & Reduction in Terms of Electrons
                                                                          • 3.3.3 Acids & Alkalis
                                                                            • 3.3.4 Neutralisation
                                                                              • 3.3.4 Strong & Weak Acids
                                                                                • 3.3.5 Effect of Hydrogen Ion Concentration on pH
                                                                                • 3.4 Electrolysis
                                                                                  • 3.4.1 Electrolysis
                                                                                    • 3.4.2 Electrolysis of Aqueous Solutions
                                                                                      • 3.4.3 Reactions at Electrodes
                                                                                        • 3.4.4 Half Equations
                                                                                      • 4. Predicting & Identifying Reactions & Products
                                                                                        • 4.1 Predicting Chemical Reactions
                                                                                          • 4.1.1 Group 1
                                                                                            • 4.1.2 Group 7
                                                                                              • 4.1.3 Group 0
                                                                                                • 4.1.4 Transition Metals
                                                                                                  • 4.1.5 The Reactivity Series
                                                                                                  • 4.2 Identifying the Products of Chemical Reactions
                                                                                                    • 4.2.1 Testing for Common Gases
                                                                                                      • 4.2.2 Testing for Aqueous Cations
                                                                                                        • 4.2.3 Testing for Aqueous Anions
                                                                                                          • 4.2.4 Flame Tests
                                                                                                            • 4.2.5 Instrumental Analysis
                                                                                                          • 5. Monitoring & Controlling Chemical Reactions
                                                                                                            • 5.1 Monitoring Chemical Reactions
                                                                                                              • 5.1.1 Concentration in g/dm3
                                                                                                                • 5.1.2 Concentration in mol/dm3
                                                                                                                  • 5.1.3 Titrations
                                                                                                                    • 5.1.5 Gas Volume Calculations
                                                                                                                      • 5.1.6 Yields
                                                                                                                        • 5.1.7 Atom Economy
                                                                                                                          • 5.1.8 Choosing a Reaction Pathway
                                                                                                                          • 5.2 Controlling Reactions
                                                                                                                            • 5.2.1 Measuring Rates
                                                                                                                              • 5.2.2 Rate Graphs
                                                                                                                                • 5.2.3 Change Rates
                                                                                                                                  • 5.2.4 Catalysts & Enzymes
                                                                                                                                  • 5.3 Equilibria
                                                                                                                                    • 5.3.1 Equilibrium
                                                                                                                                      • 5.3.2 Le Chatelier's Principle
                                                                                                                                    • 6.1 Global Challenges
                                                                                                                                      • 6.1 Improving Processes & Products
                                                                                                                                        • 6.1.1 Extracting Metals
                                                                                                                                          • 6.1.2 Biological Extraction Methods
                                                                                                                                            • 6.1.3 The Haber Process
                                                                                                                                              • 6.1.4 Making Fertilisers
                                                                                                                                                • 6.1.5 Explaining the Haber Process
                                                                                                                                                  • 6.1.6 The Contact Process
                                                                                                                                                    • 6.1.7 Life Cycle Assessment
                                                                                                                                                      • 6.1.8 Recycling Materials
                                                                                                                                                        • 6.1.9 Properties & Uses of Alloys
                                                                                                                                                          • 6.1.10 Corrosion of Iron
                                                                                                                                                          • 6.2 Organic chemistry
                                                                                                                                                            • 6.2.1 Alkanes
                                                                                                                                                              • 6.2.2 Alkenes
                                                                                                                                                                • 6.2.3 Addition Polymers
                                                                                                                                                                  • 6.2.4 Condensation Polymers
                                                                                                                                                                    • 6.2.5 DNA
                                                                                                                                                                      • 6.2.6 Alcohols
                                                                                                                                                                        • 6.2.7 Carboxylic Acids
                                                                                                                                                                          • 6.2.8 Crude Oil & Fractional Distillation
                                                                                                                                                                            • 6.2.9 Cracking
                                                                                                                                                                              • 6.2.10 Cells
                                                                                                                                                                              • 6.3 Interpreting & Interacting with Earth Systems
                                                                                                                                                                                • 6.3.1 Origins of the Atmosphere
                                                                                                                                                                                  • 6.3.2 The Greenhouse Effect
                                                                                                                                                                                    • 6.3.3 Climate Change
                                                                                                                                                                                      • 6.3.4 Atmospheric Pollutants
                                                                                                                                                                                        • 6.3.5 Potable Water
                                                                                                                                                                                      • 7. Practical Skills
                                                                                                                                                                                        • 7.1 Practical Skills
                                                                                                                                                                                          • 7.1.1 Reactivity Trends
                                                                                                                                                                                            • 7.1.2 Electrolysis
                                                                                                                                                                                              • 7.1.3 Separation Techniques
                                                                                                                                                                                                • 7.1.4 Distillation
                                                                                                                                                                                                  • 7.1.5 Identification of Species
                                                                                                                                                                                                    • 7.1.6 Titration
                                                                                                                                                                                                      • 7.1.7 Production of Salts
                                                                                                                                                                                                        • 7.1.8 Measuring Rates of Reaction


                                                                                                                                                                                                        DOWNLOAD PDF

                                                                                                                                                                                                      Author: Stewart

                                                                                                                                                                                                      Stewart has been an enthusiastic GCSE, A Level and IB Chemistry teacher for more than 30 years in the UK as well as overseas, and has been an examiner for IB and A Level, also. As a long-standing Head of Department, Stewart brings a wealth of experience to creating Topic Questions and revision materials for Save My Exams.


                                                                                                                                                                                                      Save My Exams Logo
                                                                                                                                                                                                      Resources
                                                                                                                                                                                                      Home Join Support

                                                                                                                                                                                                      Members
                                                                                                                                                                                                      Members Home Account Login

                                                                                                                                                                                                      Company
                                                                                                                                                                                                      About Us Contact Us Jobs Terms Privacy Facebook Twitter

                                                                                                                                                                                                      Quick Links
                                                                                                                                                                                                      GCSE Revision Notes IGCSE Revision Notes A Level Revision Notes Biology Chemistry Physics Maths 2022 Advance Information

                                                                                                                                                                                                       
                                                                                                                                                                                                      © Copyright 2015-2022 Save My Exams Ltd. All Rights Reserved.
                                                                                                                                                                                                      IBO was not involved in the production of, and does not endorse, the resources created by Save My Exams.