CH02 Syllabus Node
1. Energetics, Calorimetry & Hess Law Cycles
Standard enthalpy definitions (formation, combustion), calorimetry q = mc delta T, cooling curve extrapolation, Hess Law cycles, and mean bond enthalpies.
Open Topic Notes →Unit Overview & Assessment Strategy
Unit 2 (CH02) completes the AS modular tier. It examines quantitative physical chemistry (thermochemical cycles, collision rates, equilibrium yields) and introduces systematic organic reaction mechanisms (curly arrow rules, carbocation intermediates, functional group transformations, and spectroscopic analysis).
Examination Series & Windows
Unit CH02 is examined in both the January series and the May/June series. Candidates typically sit CH01 in January and CH02 in May/June, or sit both together in May/June.
Modular Cash-In Flexibility
CH02 can be combined with CH01 to cash in the International AS award (code 9621), or retained as 20% of the composite score towards the full International A-Level award (code 9622).
OxfordAQA Examiner Differentiators in Unit 2
- Precise Curly Arrow Drawing: Curly arrows represent the movement of an electron pair. They must start directly from a lone pair of electrons or the exact centre of a covalent bond, and terminate precisely on the destination atom or between atoms to form a new bond.
- Carbocation Stability Explanations: Always quote the order of stability: tertiary > secondary > primary. Explain stability in terms of the positive inductive effect of electron-releasing alkyl groups dispersing the positive charge on the carbon atom.
- Mass Spectrometry [M+1] Peak: The tiny peak one unit above the molecular ion peak is caused by the natural abundance of carbon-13 (1.1%), not an impurity.
- Enthalpy Cycle Signs: In Hess cycles, check signs carefully: formation cycle is Products minus Reactants; combustion cycle is Reactants minus Products.
CH02 Syllabus Topics (8 Modules)
Select any module below to access comprehensive revision notes, step-by-step mechanism guides, worked examples, and interactive practice questions:
CH02 Syllabus Node
2. Kinetics, Collision Theory & Catalysis
Collision theory, activation energy, Maxwell-Boltzmann energy distributions with temperature changes, and catalysed reaction profiles.
Open Topic Notes →CH02 Syllabus Node
3. Dynamic Equilibria & Equilibrium Constant Kc
Dynamic equilibrium, Le Chatelier's principle, homogeneous Kc expressions, ICE calculation tables, and temperature dependence of Kc.
Open Topic Notes →CH02 Syllabus Node
4. Alkanes & Free-Radical Substitution
Crude oil fractional distillation, thermal vs catalytic cracking, complete/incomplete combustion, and free-radical chlorination mechanism.
Open Topic Notes →CH02 Syllabus Node
5. Halogenoalkanes: Nucleophilic Substitution & Elimination
Bond polarity and reactivity, curly arrow precision, nucleophilic substitution with OH-, CN-, NH3, base elimination, and ozone depletion by chlorine radicals.
Open Topic Notes →CH02 Syllabus Node
6. Alkenes: Structure, Electrophilic Addition & Polymers
Double bond structure and E/Z isomerism, electrophilic addition mechanisms (HBr, H2SO4, Br2), carbocation stability, Markovnikov rule, and addition polymers.
Open Topic Notes →CH02 Syllabus Node
7. Alcohols: Industrial Production & Reaction Pathways
Fermentation vs hydration of ethene, oxidation of primary, secondary, and tertiary alcohols with acidified dichromate, dehydration to alkenes, and functional tests.
Open Topic Notes →CH02 Syllabus Node
8. Organic Analysis: Infrared Spectroscopy & Mass Spectrometry
Infrared absorption wavenumber ranges (O-H, C=O), fingerprint region, mass spectrometry molecular ion M+ vs [M+1] peak from 13C, and chemical test summaries.
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Mock Exam Practice
Start Unit 2 Exam Practice →
Unit 2 Authentic Mock Examination (CH02)
Complete 70-mark paper featuring 15 Section A MCQs and 6 Section B structured questions with full step-by-step mark schemes, examiner guidance, and printable worksheets.