- What makes a good Chemistry EE idea?
- Which EE guide applies to you: 2026 or 2027
- Ideas: kinetics and catalysis
- Ideas: equilibrium, acids, bases and energetics
- Ideas: electrochemistry and redox
- Ideas: analytical and food chemistry
- Ideas: materials, green chemistry and data-based essays
- Experimental or data-based: which should you choose?
- Safety, ethics and the environment
- How the 2027 criteria apply to a Chemistry EE
- How to Narrow a Chemistry Topic
- Common Chemistry EE Topic Mistakes
Quick Answer
A strong Chemistry extended essay tests one chemical relationship you can measure safely in a school lab or analyse from reliable published data, and links the result to theory. For example: 'How does temperature affect the rate constant of the iodine clock reaction, and what activation energy does an Arrhenius plot give?'. Below are 30 example research questions by topic, with why each works and what to avoid.
What You'll Learn
- From May 2027 the new EE guide applies: 30 marks, with Discussion and evaluation (8 marks) the biggest criterion
- Experimental and data-based Chemistry EEs are both valid; data-based essays still need your own analysis
- The best questions test a model, such as Arrhenius, Nernst or van 't Hoff, rather than just describe a trend
- Use SI units, a replicable method and uncertainties in your calculations
- Safety shapes topic choice: avoid toxic reagents, work at small scale, and follow your school's risk assessment
What makes a good Chemistry EE idea?
The IB's new guide describes a science extended essay as an investigation, based on a focused research question, that collects primary or secondary data using scientific methodology and reaches a valid, evidence-based conclusion. In Chemistry, the strongest ideas let you compare your data with a theoretical prediction, because that gives you something real to discuss and evaluate. Check every idea against these points.
- A defined chemical system: name the reaction, compound or equilibrium, and the variable you will change.
- A model to test: rate equations, the Arrhenius equation, Le Chatelier and Kc, the Nernst equation, Beer-Lambert, Hess's law or an adsorption isotherm.
- Measurable in a school lab: the guide warns against topics needing sophisticated equipment not usually found in school labs. A colorimeter, pH probe, data logger or burette is usually enough.
- Safe and legal at school scale, with waste you can dispose of properly.
- Different from your IA: the guide says the EE must not duplicate other work you submit for the diploma.
Pro Tip
The guide's advice for all sciences is not to overcomplicate the topic. A clean experiment with careful uncertainty analysis beats an ambitious synthesis that fails.
Which EE guide applies to you: 2026 or 2027
The new Extended essay guide was published in February 2025, taught from August 2025, and is first assessed in May 2027. November 2026 is the last session marked under the 2018 guide. Both versions centre the essay on a focused research question.
- May 2027 onwards: 30 marks across five criteria (A Framework for the essay 6, B Knowledge and understanding 6, C Analysis and line of argument 6, D Discussion and evaluation 8, E Reflection 4). Reflection is assessed from one reflective statement of up to 500 words on the Reflection and progress form (RPF), written after your final viva voce.
- November 2026 and earlier: 34 marks (A Focus and method 6, B Knowledge and understanding 6, C Critical thinking 12, D Presentation 4, E Engagement 6), with three reflections on the RPPF.
- Both: a 4,000-word limit that examiners will not read beyond, three mandatory reflection sessions, and a grade that combines with TOK for up to three diploma points. Tables, equations, formulas and calculations do not count towards the word limit.
- New in the 2027 guide: chemistry shares one set of guidance with the other sciences, and you can choose an interdisciplinary essay combining two DP subjects instead of a subject-focused one.
Ideas: kinetics and catalysis
These are illustrative starting points, not past IB essays. Kinetics works well because rates are easy to measure and theory gives clear predictions.
- IB guide example: What is the effect of manganese oxide versus copper(II) oxide in the catalysation of hydrogen peroxide at 21 °C? The guide's approach gathers background on hydrogen peroxide decomposition and catalytic mechanisms, selects variables carefully, and interprets comparative graphs using theory.
- How does temperature affect the rate constant of the persulfate-iodide (iodine clock) reaction, and what activation energy does an Arrhenius plot give? Works because you can compare your value with the literature. Avoid stopping at 'rate increases with temperature'.
- How does ionic strength, adjusted with an inert salt, affect the rate of the reaction between persulfate and iodide ions? Works because it tests the kinetic salt effect for two ions of the same charge, a theory beyond the syllabus. Avoid it unless you are ready to research the theory properly.
- How does the concentration of iron(III) ions affect the rate of the persulfate-iodide reaction? Works because it is a textbook case of homogeneous catalysis by a transition metal, so you can explain the mechanism. Avoid confusing the catalyst's effect with a simple change in ionic strength; control it.
- How does the concentration of copper(II) ions affect the rate of reaction between zinc and dilute sulfuric acid? Works because you can explain the effect through deposited copper and electrochemistry. Avoid large volumes of hydrogen; work at small scale.
- How does temperature affect the rate of hydrolysis of aspirin, followed by colorimetry of the iron(III)-salicylate complex? Works because it links kinetics to drug stability. Avoid letting pH drift between runs.
Ideas: equilibrium, acids, bases and energetics
These questions suit you if you like quantitative analysis and want to test an equilibrium or thermodynamic model.
- How does temperature affect the equilibrium constant of the iron(III) thiocyanate equilibrium, measured by colorimetry, and what enthalpy change does a van 't Hoff plot give? Works because the coloured complex gives precise absorbance data. Avoid skipping a calibration curve.
- IB guide example: How does the electronegativity of the distinctive atom in inorganic mono-oxoacids affect its pKa values? The guide calls this typical data-based research: background on acid-base theory, pKa and the inductive effect, values from several sources, and a graph analysed against theory.
- How does temperature affect the solubility product of calcium hydroxide, determined by titration? Works because its solubility falls as temperature rises, an unexpected trend you can explain with the enthalpy of solution. Avoid carbon dioxide from the air reacting with your solutions.
- How does the number of chlorine substituents affect the pKa of ethanoic acid, and how well does the inductive effect explain the trend? Works as a secondary-data essay using published pKa values. Avoid handling the chloroethanoic acids themselves, which are corrosive and toxic.
- How does the total concentration of an ethanoic acid and sodium ethanoate buffer affect its buffer capacity against added sodium hydroxide? Works because the Henderson-Hasselbalch equation gives predictions to test with a pH probe. Avoid relying on indicator colours.
- How does temperature affect the pH of pure water, and how well do the results match published values of Kw? Works because the pH of neutral water falls below 7 as temperature rises, which surprises most readers. Avoid dissolved carbon dioxide; use freshly boiled water and a calibrated probe.
- How does the enthalpy of neutralisation of sodium hydroxide differ between strong and weak acids, and what does the difference suggest about the energy of ionisation? Works because Hess's law gives a clear framework. Avoid ignoring heat losses; use an insulated cup and a cooling correction.
Ideas: electrochemistry and redox
Electrochemistry questions are cheap to run and test equations with numbers you can predict in advance.
- How does the concentration of copper(II) ions affect the cell potential of a zinc-copper (Daniell) cell, and how closely do the results fit the Nernst equation? Works because theory gives an exact prediction. Avoid a voltmeter with poor resolution, and record its uncertainty.
- How does temperature affect the cell potential of a zinc-copper cell, and what entropy change does the slope imply? Works because it links electrochemistry and thermodynamics in one graph. Avoid uneven temperatures between the two half-cells.
- How does current affect the efficiency of copper electroplating, comparing actual mass deposited with Faraday's laws? Works because there is a theoretical value to compare. Avoid weighing wet cathodes; dry them the same way each time.
- How does sodium chloride concentration affect the corrosion rate of iron nails over two weeks, measured by mass loss? Works because it is simple and has clear real-world relevance. Avoid uncontrolled oxygen exposure and coated nails.
- How does storage time and temperature affect the vitamin C content of fresh orange juice, measured by iodometric or DCPIP titration? Works because redox titrations are precise and repeatable. Avoid comparing brands with unknown processing histories.
Ideas: analytical and food chemistry
Analytical questions work when the method is standard and the comparison has a chemical explanation, not just a ranking of brands.
- How does cooking method affect the iron content of spinach, determined by colorimetry with thiocyanate? Works because sample preparation and calibration give real analytical depth. Avoid incomplete digestion of samples; run a pilot.
- What percentage of eggshell is calcium carbonate, determined by back titration, and how does it vary with shell source? Works because the method is well established. Avoid a comparison with no chemistry to explain.
- How does water hardness from different local sources compare, measured by EDTA titration, and how does it relate to local geology? Works because complexometric titration is precise and the explanation is chemical. Avoid too few samples per source.
- How does steeping temperature affect the tannin content of black tea, measured by a permanganate titration? Works because it connects extraction to solubility and temperature. Avoid unclear end points; practise the titration first.
- How does brewing time affect the caffeine concentration of coffee, measured by UV-visible spectrophotometry, if your school has one? Works because Beer-Lambert calibration gives quantitative data. Avoid ignoring other compounds that absorb at the same wavelength.
- How does water temperature affect the dissolved oxygen concentration of a local stream, measured by Winkler titration? Works because it links gas solubility to a real environmental issue. Avoid delays between sampling and fixing the oxygen.
Ideas: materials, green chemistry and data-based essays
These suit you if you want a real-world angle, or if lab time is limited and a data-based essay makes more sense.
- How does glycerol content affect the tensile strength of starch-based bioplastic films? Works because a simple rig gives quantitative data linked to polymer structure. Avoid films of uneven thickness; measure and control it.
- How does the methanol-to-oil ratio affect the yield of biodiesel from used cooking oil? Works because it links reaction stoichiometry to sustainability. Avoid it unless your school can manage methanol and strong base safely in a fume cupboard.
- How effectively does banana peel adsorb methylene blue dye compared with activated charcoal, and does a Langmuir or Freundlich isotherm fit better? Works because isotherm modelling adds analytical depth. Avoid uncontrolled particle size and pH.
- How effective is Moringa oleifera seed powder compared with alum at reducing the turbidity of water samples? Works because both are real coagulants and you can explain charge neutralisation. Avoid measuring turbidity by eye.
- How does branching in alkane isomers affect boiling point, using NIST Chemistry WebBook data, and how well does surface area explain the trend? Works as a data-based essay with clear intermolecular force theory. Avoid comparing too few isomers.
- How well do the Born-Landé and Kapustinskii equations predict experimental lattice enthalpies for Group 1 halides? Works because you test theoretical models against Born-Haber values. Avoid plotting data booklet values without testing a model.
Experimental or data-based: which should you choose?
Both are valid under the new guide, and every EE must include a review of the literature. Choose the route that gives you the cleanest data and the strongest link to theory.
- Experimental: use controlled independent variables and a standardised method that someone else could repeat. Use SI units, label tables and graphs with units, and show uncertainties in example calculations, as the guide requires.
- Data-based: use several sources for your values, explain how you selected them, and choose sources with similar standardised methods. You may reproduce published tables, but the analysis must be your own.
- Mixed: run a smaller experiment and compare your results with literature values, which strengthens your evaluation.
- External labs: allowed, but the guide says the methods must be your own, not just those set by the organisation.
- Unexpected results: the guide says negative results are as valid as positive ones. Explain them with theory and evaluate the method.
Safety, ethics and the environment
The guide says your safety and the safety of others is paramount in research that involves experimentation, and calls the IB's Sciences experimentation guidelines essential reading. They cover handling of equipment, chemicals and waste disposal, and risk assessment. Plan around these points from the start.
- Write a risk assessment with your teacher before any practical work, and never run experiments alone or at home.
- Avoid highly toxic, carcinogenic or explosive reagents; a safer alternative or a data-based question is usually available.
- Work at the smallest practical scale, especially with flammable solvents or gases.
- Dispose of heavy-metal and organic waste as your school directs, not down the sink.
- Use AI tools only as a cited research aid and check what they produce; presenting AI-written text as your own is an academic integrity breach.
Watch Out
If the only way to answer your question safely needs equipment or reagents your school cannot provide, change the question rather than cut corners.
How the 2027 criteria apply to a Chemistry EE
The guide's science notes show what examiners look for under each criterion.
- A: Framework for the essay (6). The research question decides the method, which must yield scientific data that answers it. Define and justify variables, use SI units, make tables and graphs easy to read, process all data and include uncertainties.
- B: Knowledge and understanding (6). Explain the underlying chemistry with accurate terminology, for example rate equations and mechanisms for a kinetics essay. This is especially critical in data-based essays.
- C: Analysis and line of argument (6). Use standard quantitative and statistical methods, including mathematical transformations such as logarithmic plots, that answer the question directly. Keep every section linked to the question.
- D: Discussion and evaluation (8). Discuss results critically in their chemical context, using sources to support your conclusion. Make the conclusion a synthesis, not a repeat of results, and evaluate unresolved issues, improvements and your sources.
- E: Reflection (4). Marked only from your reflective statement on the RPF.
How to Narrow a Chemistry Topic
Test each idea against feasibility, safety and depth of theory before you write the final question.
- 1Start with an area you enjoy: kinetics, equilibrium, electrochemistry, analysis, energetics or materials.
- 2Find the equation or model that governs it, because that is what your data will test.
- 3Check equipment, reagents and safety with your teacher.
- 4Write the research question with the system, the independent variable and its range, and the measured quantity.
- 5Run a pilot to check that the method gives readings precise enough to show a trend beyond your uncertainties.
Common Chemistry EE Topic Mistakes
Most Chemistry EEs that disappoint go wrong in the plan, not the write-up. An IB Chemistry tutor can strengthen the Chemistry your method depends on, such as the techniques and calculations; whether it works in your school lab is a question for your supervisor.
- Overused IA-style topics, such as the enthalpy of combustion of alcohols or temperature versus rate with no model tested.
- Ranking brands or products with no chemical explanation for the differences.
- Uncertainties larger than the effect you are measuring, discovered too late to change the method.
- Ignoring theory that contradicts your results instead of discussing it.
- A data-based essay that copies values without your own processing and analysis.
- Putting key working in appendices: examiners are not required to read them, and they do not read beyond 4,000 words.
Watch Out
A technically impressive topic is not necessarily a strong one if the method, data or explanation are too weak to support a convincing essay.
Frequently Asked Questions
A good Chemistry EE topic tests one chemical relationship that you can measure safely, or analyse from reliable data, and compare with a theoretical model. For example, 'How does copper(II) ion concentration affect the cell potential of a Daniell cell, and how closely do the results fit the Nernst equation?'. It should be different from your IA and feasible with school equipment.
No. The new guide says a science EE can collect primary or secondary data, and it gives a data-based chemistry example on the pKa of inorganic oxoacids. A data-based essay must use several sources, explain how values were selected, and contain your own analysis. Every EE must also include a review of the literature.
There is no fixed number in the guide. What matters is enough levels of the independent variable to show a reliable trend, and enough repeats to estimate uncertainty, so that a conclusion is supported by the data. A pilot run tells you whether your planned range and precision are enough.
The guide says you and your supervisor must make sure the EE does not duplicate other work submitted for the diploma, such as an IA. You can work in a related area, but the research question, method and data must be clearly different. Raise any overlap with your supervisor early.
It is marked out of 30 against five criteria: Framework for the essay (6), Knowledge and understanding (6), Analysis and line of argument (6), Discussion and evaluation (8) and Reflection (4). Reflection is assessed only from your 500-word statement on the RPF. Essays in the November 2026 session, the last under the 2018 guide, are marked out of 34 on its criteria.
The new IB Extended essay guide gives two chemistry examples: manganese oxide versus copper(II) oxide as catalysts for hydrogen peroxide decomposition (experimental) and electronegativity versus pKa in inorganic oxoacids (data-based). Both are on this page. Your EE coordinator can access more support material and subject reports on the IB's Programme Resource Centre.
Yes. An IB Doctor tutor, verified and with a score of 40 or more IB points, can help you understand the models and techniques behind topics you are considering and practise uncertainty analysis on other data in online sessions, while the research question, method and essay stay your own. Your supervisor remains the only person who comments in writing on your full draft. Matching usually happens within 24 hours.