How to Write a Strong IB Chemistry IA - 2025 Guide

The updated 2025 Chemistry IA is clearer than ever—but you still need to show precision, insight, and ownership of your investigation.

What’s New in the 2025 IB Chemistry IA?

The 2025 IB Chemistry specification puts more emphasis on scientific thinking, data literacy, and real-world connections. The Internal Assessment still counts for 20% of your final grade, but expectations are now more structured.

Key updates include:

• Greater emphasis on uncertainty and data analysis

• Personal engagement now means justifying design decisions

• Real-world relevance is encouraged

• No page limit, but clarity and structure are essential

• Clear focus on scientific method and critical thinking

What the Chemistry IA Is Really About

Your Chemistry IA is a student-designed investigation that demonstrates your ability to:

• Ask a clear research question

• Design and carry out an experiment

• Collect and analyse quantitative data

• Interpret results with scientific theory

• Evaluate your method and findings

• Communicate your work like a chemist

IB Chemistry IA Assessment Criteria (2025 Edition)

Assessment Criteria (2025 Edition)

Criterion	What It Assesses
Design	Research question, planning, controls, scientific rationale
Data Collection & Processing	Data quality, uncertainties, graphs, analysis
Discussion & Conclusion	Interpretation, theory link, critical evaluation
Communication	Clarity, structure, formatting, correct chemical language

Each is scored out of 6, for a total of 24 marks.

Step 1: Choosing a Strong IA Topic

The best topics are:

• Focused on one independent variable

• Quantitative and measurable

• Scientifically explainable

• Feasible in a school lab

Avoid:

• Comparing commercial products

• Overly complex variables

• Projects without clear chemical theory

2025-Spec Example IA Topics

2025-Spec Example IA Topics

Topic Area	Research Question
Kinetics	How does ionic strength affect the rate of the thiosulfate-acid reaction?
Acids and Bases	How does dilution affect the buffer capacity of citric acid?
Electrochemistry	How does H₂O₂ concentration affect cell voltage?
Equilibrium	How does adding a common ion affect Fe³⁺/thiocyanate equilibrium?
Organic	How does carbon chain length affect alcohol combustion enthalpy?
Environmental	How does nitrate concentration in local rivers vary after rainfall?

👉 Use local or personal context to boost engagement.

Step 2: Framing a Great Research Question

A strong IA question should:

• Be focused and specific

• Use one independent and one dependent variable

• Allow for control of variables

Examples:

• ✅ “How does temperature affect the decomposition rate of H₂O₂ using MnO₂ catalyst?”

• ❌ “What affects enzyme activity?” (too vague)

Step 3: Designing the Investigation

Examiners want to see justification and control. Include:

• A hypothesis

• Rationale for variable selection

• Full equipment list

• Clear, step-by-step method

• Safety and ethics considerations

2025 Tip: Show you’ve thought critically about design—not just followed a worksheet.

Step 4: Data Collection & Processing

Raw Data:

• Clear tables with units and uncertainties

• Repeated trials

• Consistent significant figures

Processed Data:

• Calculations with units

• Graphs with error bars and best-fit lines

• Uncertainty propagation where relevant

Tip: Use tools like Excel, LoggerPro, or Google Sheets for graphs and calculations.

Step 5: Discussion and Conclusion

Explain what your data shows using chemical principles.

Include:

• Trend analysis (quantitative and qualitative)

• Connection to theory (activation energy, collision theory, etc.)

• Explanation of anomalies or unexpected results

• Specific evaluation of method (not just “human error”)

Conclusion must:

• Directly answer your research question

• Refer to specific data

• Include a confidence level in your findings

IB Chemistry IA Structure (2025)

1. Title and Research Question

2. Introduction and Hypothesis

3. Design and Justification

4. Safety and Ethics

5. Method and Materials

6. Raw Data Table(s)

7. Processed Data + Graphs

8. Discussion and Interpretation

9. Conclusion and Evaluation

10. References

11. Appendix (if needed)

💡 How to Show Personal Engagement (2025)

You don’t get marks for enthusiasm—you get marks for showing ownership and agency.

Do this by:

• Choosing a topic with real relevance to you

• Justifying your experiment choices

• Explaining how you responded to challenges

Example:

“As someone interested in pharmacology, I explored how pH affects aspirin hydrolysis. I adjusted the procedure after an early trial revealed inconsistent timing.”

⚠️ Common Mistakes and How to Fix Them

Common Mistakes and Fixes

Mistake	Fix
Vague research question	Focus on one measurable variable
No control variables	Identify and hold variables constant
Poor graph labels	Always include axis titles, units, and legends
No link to theory	Explain results using IB syllabus concepts
No reflection in conclusion	Discuss anomalies, limitations, and confidence level
“Human error” as evaluation	Be specific about uncertainty sources

Final IA Checklist (2025)

• Focused, quantitative research question

• Justified method with controlled variables

• Clear tables with uncertainties and trials

• Graphs with error bars and labels

• Trends explained with theory

• Thoughtful, evidence-based evaluation

• Structured, formal, scientifically written

• Personal engagement demonstrated

• 6–12 pages of focused content

• Referenced sources included

Example Mini IA: 2025 Style

Title: The Effect of pH on the Rate of the Iodine Clock Reaction
Research Question: How does pH affect the time taken for colour change in the iodine clock reaction?
Method:

• Buffers used to control pH (3 to 7)

• Stopwatch used for timing

• Repeat each trial 3x
  Processing:

• Time plotted against pH

• 1/time calculated for rate

• Error bars added
  Conclusion:

• Rate increases as H⁺ concentration increases

• Consistent with collision theory

• Minor fluctuations due to manual timing

Final Thoughts

The updated 2025 Chemistry IA is clearer than ever—but you still need to show precision, insight, and ownership of your investigation.

Choose a good question. Justify your design. Analyse with care. Reflect honestly. Present your thinking like a scientist.

Need help crafting or refining your IB Chemistry IA?
Dr Marguerite Quinn is an experienced IB Chemistry tutor with a PhD in Chemistry and 3,470+ hours of teaching expertise. She offers personalised support on IA topic selection, structure, analysis, and review.

Book a 15-minute consultation to talk about how you can support youn in achieving a top score in your Chemistry IA.