5 Topics That Always Come Out In A-Level Chemistry Exams

Written By Opeyemi Johnson

If you're revising for OCR A A-Level Chemistry, you’ve probably wondered: What topics actually come up every year? After analysing the past five years of exam papers, I’ve identified 5 frequently examined topics - and I’m giving you brief model answers to typical questions you might encounter so you can study smarter and score higher.

Whether you're aiming for an A* or just trying to boost your confidence, this guide is a starting point to strategic revision.

 

1. Amount of Substance (Moles & Stoichiometry)

What it’s about: Calculating quantities in chemical reactions using the mole concept.

You need to know:

  • Mole calculations

  • Empirical and molecular formulae

  • Ideal gas equation

  • Titration calculations

 

2. Enthalpy Changes & Hess’s Law

What it’s about: Energy changes in reactions and how to calculate them.

You need to know:

  • ΔH definitions (formation, combustion…)

  • Bond enthalpies

  • Hess cycles

  • Calorimetry (q = mcΔT)

 

3. Rates of Reaction

What it’s about: How fast reactions occur and what affects them.

You need to know:

  • Rate equations

  • Orders of reactants and overall order

  • Rate constant (k) and unit derivation

  • Graphical analysis

 

4. Redox & Electrode Potentials

What it’s about: Electron transfer reactions and electrochemical cells.

You need to know:

  • Oxidation states

  • Half equations

  • Standard electrode potentials

  • Cell diagrams and feasibility

 

5. Analytical Techniques (IR, Mass Spec, NMR)

What it’s about: Identifying compounds using instrumental methods.

You need to know:

  • How to determine empirical formulae

  • Common IR absorption peaks

  • How to interpret MS

  • NMR chemical shifts and splitting

 

Final Tip: Practise With Purpose

Use these topics to guide your revision - but don’t just read them. Practise past papers, draw out mechanisms, and practise teaching the concepts to others or to yourself in the mirror. Active recall and spaced repetition are your best friends.

While these topics are a great place to begin revising strategically, do remember that this list is only a reflection of past exams and not meant to offer any assurance that they will appear in upcoming exams.

I go into greater detail with the top 10 examined A-Level Chemistry topics for OCR. The guide includes topic summaries, important takeaways with exam-style questions and A* model answers expected by examiners for each topic in the full guide - all you need to know to start answering exam questions on these topics confidently.

Read the Full Guide
 

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Opeyemi Johnson