IB Chemistry IA Topics That Examiners Love (2026 Edition)
IB Chemistry IA Topics That Examiners Love (2026 Edition) Your IB Chemistry Internal Assessment — now officially called the Scientific Investigation — is worth...
Key Takeaways
- Before choosing a topic, understand what the examiners are actually marking.
- A strong IA topic has four characteristics: a single, clearly defined independent variable that you can manipulate; a dependent variable that you can measure quantitatively (with numbers, not just obs.
- Choosing a topic that's too ambitious.
- Weeks 1-2: Research and select your topic.
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Frequently Asked Questions
What makes a good Chemistry IA topic?
A good Chemistry IA topic should be personally interesting, feasible with school lab equipment, allow for quantitative data collection, and have a clear independent and dependent variable. Avoid overly common topics and choose something that lets you demonstrate genuine scientific inquiry.
For more on this topic, explore our guide on 3 Top Chemistry Ia Topics That Score High Marks.
How long should an IB Chemistry IA be?
The IB Chemistry IA should be approximately 6-12 pages, with a recommended word count of around 2,000 words (excluding tables, graphs, and references). Focus on quality analysis rather than length.
What is the most common mistake in Chemistry IAs?
The most common mistake is choosing a topic that is too broad or too simple. Students also frequently lose marks for insufficient error analysis, lack of personal engagement, and failing to connect their findings to the broader scientific context.
Can I use an AI solver for my Chemistry IA?
AI solvers can be helpful for checking calculations and understanding concepts during your research phase, but your IA must reflect your own original work and thinking. Always verify AI outputs and cite any tools you used appropriately.
Your IB Chemistry Internal Assessment — now officially called the Scientific Investigation — is worth 20% of your final grade. That's the same weight as an entire exam paper. Unlike exams, though, you have weeks to plan, draft, and revise your IA before submission. The students who score highest aren't necessarily the ones with the most complex experiments. They're the ones who choose a focused, measurable research question and execute every criterion with precision.
The 2025 curriculum restructured IB Chemistry around two organising concepts: Structure and Reactivity. The old option topics (Materials, Biochemistry, Energy, Medicinal Chemistry) are gone, replaced by a streamlined syllabus with 22 topics built around the idea that structure determines reactivity. Your IA should reflect this updated framework — and the topic ideas below are organised accordingly.
This guide gives you 30 IA topic ideas across the major areas of the syllabus, explains what makes each one work, and walks you through the criteria that determine your score.
If you're feeling uncertain about where to start with your Chemistry IA, you're not alone — it's one of the most common challenges IB Chemistry students face. An experienced Chemistry tutor can help you develop your topic, structure your argument, and avoid the mistakes that cost marks. Tell us what you need help with →
How the IA Is Assessed: The 5 Criteria
Before choosing a topic, understand what the examiners are actually marking. Your Scientific Investigation is assessed on five criteria, each worth a maximum of 6 marks, for a total of 24:
For more on this topic, explore our guide on How to Write an Excellent Chemistry Ia Top Chemistry Ia Topics and Tips.
Personal Engagement (6 marks): Does the investigation reflect genuine personal interest or independent thinking? Examiners look for evidence that you chose this topic because it matters to you — not because you copied it from a list. Context matters here: connecting your research question to a personal experience, a local issue, or a real-world application demonstrates engagement far more effectively than stating "I find chemistry interesting."
Exploration (6 marks): Is your research question focused and scientifically grounded? This criterion assesses the quality of your methodology, your awareness of variables, and whether you've addressed safety, ethical, and environmental considerations. A clear, testable research question with well-defined independent and dependent variables scores highest.
Analysis (6 marks): How effectively do you process and present your data? This includes appropriate use of tables, graphs, uncertainties, and statistical analysis. Raw data alone won't earn high marks — you need to show processed data with clear calculations and meaningful visual representations.
Evaluation (6 marks): Can you critically reflect on your results? This means identifying specific limitations in your method (not just "human error"), suggesting realistic improvements, and comparing your findings to accepted scientific values or published literature.
Communication (6 marks): Is your report well-structured, clearly written, and within the 3,000-word limit? Proper use of scientific terminology, consistent referencing, and logical organisation all contribute here.
Choosing the Right Topic: What Works and What Doesn't
A strong IA topic has four characteristics: a single, clearly defined independent variable that you can manipulate; a dependent variable that you can measure quantitatively (with numbers, not just observations); enough existing literature to compare your results against; and feasibility with school laboratory equipment and standard safety protocols.
Topics that tend to score poorly share common problems. They're too broad ("How does temperature affect chemical reactions?"), too qualitative ("Observing colour changes in different solutions"), or too dependent on a single measurement with no opportunity for meaningful data analysis.
Topic Ideas by Syllabus Area
Structure 1: Atomic and Molecular Structure
1. Effect of molecular size on the enthalpy of combustion of alcohols. Measure heat released when burning methanol through pentanol using a calorimeter. Plot enthalpy of combustion against number of carbon atoms to establish a trend. Strong data analysis potential with percentage error calculations against literature values.
2. Relationship between bond length and bond energy in diatomic molecules using spectroscopic data. Use published spectroscopic data to investigate trends in bond properties across a period or group. This works well as a database investigation if lab access is limited.
3. Investigating the relationship between atomic radius and first ionisation energy across a period. Another data-based investigation using published values. Strong for demonstrating understanding of periodicity and electronic structure.
Structure 2: Bonding and Intermolecular Forces
4. How does the number of hydroxyl groups affect the viscosity of organic compounds? Compare flow rates of methanol, ethanol, ethane-1,2-diol, and glycerol. Connects intermolecular forces (hydrogen bonding) to a measurable physical property.
5. Effect of chain length on the surface tension of alcohols. Use a stalagmometer or drop-counting method to measure surface tension. Relates London dispersion forces to a physical property with clear quantitative data.
6. Investigating how polarity affects solubility of organic compounds in different solvents. Measure solubility of a series of compounds in polar vs non-polar solvents. Connects the "like dissolves like" principle to experimental data.
Structure 3: Classification of Matter
7. Determining the empirical formula of magnesium oxide by combustion. A classic experiment that produces clean quantitative data. Compare your experimental ratio to the theoretical 1:1 ratio and analyse sources of error.
8. Effect of crystallisation temperature on the purity of a recrystallised product. Measure melting points of aspirin or benzoic acid recrystallised at different cooling rates. Connects purification techniques to measurable outcomes.
Reactivity 1: Rates of Reaction (Kinetics)
9. Effect of temperature on the rate of reaction between sodium thiosulfate and hydrochloric acid. Measure the time for the solution to turn opaque at different temperatures. Calculate rate constants and use the Arrhenius equation to determine activation energy. This is a strong HL topic with excellent data analysis potential.
10. Effect of concentration on the rate of decomposition of hydrogen peroxide catalysed by manganese dioxide. Measure oxygen gas production using a gas syringe at different H₂O₂ concentrations. Determine the order of reaction from your data.
11. Investigating the catalytic efficiency of different transition metal oxides on the decomposition of hydrogen peroxide. Compare MnO₂, Fe₂O₃, and CuO as catalysts by measuring initial rates of oxygen production. Connects to transition metal chemistry and catalysis.
12. Effect of surface area on the rate of reaction between marble chips and hydrochloric acid. Vary particle size (powder, small chips, large chips) and measure CO₂ production over time. Straightforward experiment with clear results.
13. Determining the activation energy of the iodine clock reaction. Run the reaction at multiple temperatures, measure induction times, and use an Arrhenius plot (ln k vs 1/T) to calculate Ea. Excellent for demonstrating HL-level data analysis.
Reactivity 2: Equilibrium and Acid-Base Chemistry
14. Effect of temperature on the equilibrium constant of the cobalt chloride equilibrium. Measure absorbance at different temperatures using a colorimeter. Calculate Kc values and relate the shift to Le Chatelier's principle and enthalpy of reaction.
15. Determining the Ka of a weak acid by half-equivalence point titration. Titrate ethanoic acid with NaOH, identify the half-equivalence point where pH = pKa, and compare your result to the literature value. Clean experimental design with strong analytical potential.
16. Comparing the buffer capacity of different buffer solutions. Prepare buffers at various concentrations and measure how much strong acid or base is needed to change the pH by one unit. Relevant to biological and environmental chemistry.
17. Effect of common ion on the solubility of a sparingly soluble salt. Measure the solubility of calcium hydroxide in solutions containing different concentrations of calcium chloride. Calculate Ksp values and compare to literature.
18. Investigating the effect of pH on the rate of enzyme-catalysed hydrolysis of starch by amylase. Bridges chemistry and biology. Measure the time for starch to be fully hydrolysed at different pH values using iodine testing.
Reactivity 3: Electrochemistry and Thermochemistry
19. Measuring the electrochemical series: comparing experimental cell potentials with standard values. Construct galvanic cells using different metal combinations and measure EMF values. Compare your experimental series to the standard electrode potential table.
20. Effect of electrolyte concentration on the EMF of a galvanic cell. Vary the concentration of one half-cell and measure cell potential. Apply the Nernst equation to your data for HL-level analysis.
21. Determining the enthalpy of neutralisation of strong and weak acids. Compare the heat released when HCl vs CH₃COOH reacts with NaOH. Explain the difference using incomplete dissociation of the weak acid.
22. Investigating Hess's Law by measuring enthalpy changes for related reactions. Use calorimetry to measure ΔH for individual reactions and verify that the sum equals the ΔH of the overall reaction. A classic IA that reliably produces good data.
23. Effect of current on the mass deposited during electrolysis of copper sulfate solution. Vary the current and measure the mass of copper deposited at the cathode. Apply Faraday's laws and calculate percentage efficiency.
Reactivity 4: Organic Chemistry
24. Comparing the rate of hydrolysis of primary, secondary, and tertiary halogenoalkanes. Use the silver nitrate test to measure the rate of precipitate formation. Connects SN1 vs SN2 mechanisms to experimental evidence.
25. Effect of temperature on the rate of esterification. Measure the yield of an ester (by titrating unreacted acid) at different temperatures. Connects organic reactions to kinetics and equilibrium.
26. Determining the percentage of ethanoic acid in commercial vinegar by titration. A practical, real-world application with reliable quantitative data. Multiple trials produce good statistical analysis opportunities.
Applied and Cross-Topic Investigations
27. Measuring vitamin C content in fruit juices using iodometric titration. Compare fresh vs stored juices, or different brands. The real-world connection strengthens personal engagement, and the titration produces precise quantitative data.
28. Investigating the effect of water hardness on soap efficiency. Measure the volume of soap solution needed to produce a lasting lather in water samples with different calcium ion concentrations. Connects to environmental and everyday chemistry.
29. Effect of temperature on the dissolved oxygen content of water. Use a dissolved oxygen probe or Winkler method to measure O₂ at different temperatures. Relevant to environmental chemistry and climate science.
30. Analysing the caffeine content of different tea varieties using UV-Vis spectrophotometry. If your school has a spectrophotometer, this produces excellent quantitative data with strong real-world relevance.
Common IA Mistakes to Avoid
Choosing a topic that's too ambitious. You don't need a university-level experiment. A well-executed investigation of a straightforward reaction will outscore a poorly controlled investigation of a complex system every time. The criteria reward precision and rigour, not complexity.
You might also find these guides helpful: How to Analyze Data for Chemistry Ia Topics a Step by Step Guide and How to Choose the Best Chemistry Ia Topics a Step by Step Guide.
Neglecting uncertainties. Every measurement has an uncertainty, and examiners expect you to propagate these through your calculations. If your final result has no uncertainty range, you're missing marks in both Analysis and Evaluation.
Writing "human error" as a limitation. This is the single most common mistake in IA evaluations. "Human error" is not a valid scientific limitation. Instead, identify specific systematic or random errors: "The thermometer had a resolution of ±0.5°C, which introduces an uncertainty of approximately 2% in the temperature readings."
Ignoring the word limit. The 3,000-word maximum is strictly enforced. Examiners stop reading at 3,000 words, so anything beyond that limit won't earn marks. Edit ruthlessly — move detailed calculations to an appendix if needed.
Copying a topic without making it your own. Using a standard experiment is fine, but personal engagement requires you to bring something original. Adapt the research question to a context that interests you, test an additional variable, or connect the results to a real-world application specific to your community.
Timeline for Completing Your IA
Weeks 1-2: Research and select your topic. Formulate a clear research question with defined variables. Write a preliminary methodology.
Weeks 3-4: Conduct a pilot experiment. Identify problems with your method and refine before collecting final data. This step separates strong IAs from average ones.
Weeks 5-7: Collect your final data. Run enough trials for meaningful statistical analysis (at least 5 trials per data point, with a minimum of 5 different values for your independent variable).
Weeks 8-9: Process data, create graphs, perform calculations. Write your Analysis and Conclusion sections while the data is fresh.
Weeks 10-11: Write the Evaluation, refine Personal Engagement and Exploration sections. Check that every criterion is addressed.
Week 12: Edit for clarity, check the word count, verify all references, and submit.
Getting Expert Support
The difference between a 16/24 and a 22/24 IA often comes down to understanding what examiners actually reward at each criterion. Our IB Chemistry tutors include current and former IB examiners who have marked hundreds of Scientific Investigations. They can review your research question before you start experimenting, identify weaknesses in your methodology, and provide criterion-specific feedback on your draft.
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Related: IB Subjects Page | How to Read Your IB Grades: The Complete 1-7 Scale
