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Chemistry Extended Essay Guide
A guide to designing a rigorous IB Chemistry Extended Essay with correct methodology, data analysis, and chemical theory.
What is a Chemistry Extended Essay?
The Chemistry Extended Essay (EE) is one of the most challenging and rewarding parts of the IB Diploma. Below you will find everything you need to choose a strong topic, design your methodology, and write a high-scoring EE in Chemistry.
Word Count
3,500 – 4,000 words
Excluding bibliography, abstract, and appendices. Budget every section carefully before you start writing.
Assessment
Graded A–E
Combined with the TOK essay for up to 3 bonus IB Diploma points. A strong EE and TOK = maximum bonus.
Timeline
12–18 months
From initial topic to final submission. Most students underestimate this. Start early and plan backwards from your deadline.
Supervision
3 required meetings
Initial, interim, and final (viva voce). Each requires an RPPF reflection. Your supervisor approves your RQ.
Strong Chemistry EE Topic Ideas
| Topic Idea | Why It Works | Difficulty |
|---|---|---|
| How does temperature affect the rate of the iodine clock reaction? | Kinetics, Arrhenius equation, measurable | Easy |
| How does pH affect the effectiveness of aspirin as an analgesic? A spectrophotometric study | Medicinal chemistry, UV-Vis spectroscopy | Medium |
| To what extent does electronegativity difference predict the solubility of ionic compounds in water? | Physical chemistry, data analysis, clear hypothesis | Medium |
| How does the concentration of H₂O₂ affect the rate of catalytic decomposition using MnO₂? | Kinetics, catalysis, measurable | Easy |
| How does varying the carbon chain length of alcohols affect their standard enthalpy of combustion? | Thermochemistry, measurable, theory-rich | Medium |
| To what extent can cyclic voltammetry be used to determine the redox behaviour of vitamin C? | Electrochemistry, analytical chemistry, advanced | Hard |
Subject-Specific Advice
Safety
Complete risk assessment first
Chemistry EEs often involve hazardous chemicals. Complete a risk assessment and discuss it with your teacher BEFORE starting any experiment. Safety is non-negotiable.
Uncertainties
Propagate errors correctly
Report all measurements with absolute uncertainty. Propagate uncertainties through calculations. Discuss how measurement uncertainty affects your conclusions.
Chemical Theory
Explain mechanisms
Do not just report your results — explain the chemical mechanism. If rate increases with temperature, apply collision theory and the Arrhenius equation. Link results to theory.
Data Processing
Show all working
Show raw data tables, processed data, graphs with appropriate axes and uncertainties, and statistical analysis. Examiners need to follow your data processing completely.
Assessment & Common Mistakes
Assessed on: chemical knowledge, experimental design, data processing (including uncertainties), and critical evaluation. Chemistry EEs without proper uncertainty analysis and mechanistic explanation are assessed in the lower mark bands.
⚠ Common Pitfall
Many Chemistry EEs report data without explaining why the observed trend occurs chemically. If your reaction rate increased, explain it using collision theory and activation energy — do not just say “the rate increased.” The chemical mechanism and theory are central to a high-scoring EE.
Chemistry EE Checklist
- ✓ My RQ is specific and quantifiable — I can measure a clear outcome
- ✓ I completed a risk assessment and discussed it with my teacher
- ✓ All measurements are reported with absolute and percentage uncertainty
- ✓ I propagated uncertainties through my calculations
- ✓ My discussion explains the chemical mechanism behind my results
- ✓ I acknowledge instrumental and systematic sources of error
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