The current IB Chemistry IA structure should organize your scientific investigation around four equally weighted criteria: Research design, Data analysis, Conclusion, and Evaluation. Your individual written report has a firm maximum of 3,000 words, although several elements, including data tables, equations, calculations, citations, and the bibliography, are excluded from that count.
The IB does not prescribe one compulsory set of section headings. However, a structure aligned with the four assessment criteria makes evidence easy to locate and reduces the risk of overlooking an assessed requirement. This guide explains the official rules, a practical outline, recommended word allocations, and formatting conventions for students assessed under the course first examined in 2025.
Current IB Chemistry IA requirements
The IA is officially called the scientific investigation. It is an open-ended investigation in which you gather and analyse data to answer a research question that you have formulated. According to the official IB Chemistry subject brief, it is designed for approximately 10 hours, contributes 20% of the final Chemistry grade at both SL and HL, and produces a written report of no more than 3,000 words.
SL and HL reports are assessed using the same four criteria, each worth six marks:
Assessment criterion
Maximum marks
Weighting within the IA
Main focus
Research design
6
25%
Research context, question, methodological decisions, and reproducible method
Data analysis
6
25%
Recording, processing, uncertainty treatment, and presentation of data
Conclusion
6
25%
A justified answer connected to the data and accepted scientific context
4.7
X
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Evaluation
6
25%
Methodological limitations, their effects, and realistic improvements
Total
24
100%
Complete scientific investigation
There is no longer a separate criterion for personal engagement, exploration, or communication. Those belong to the previous course. Clear scientific communication still matters because assessors can award marks only for evidence they can understand and connect to the current criteria.
The IB's Chemistry curriculum update also confirms that Conclusion and Evaluation together account for 50% of the IA marks. Students should therefore avoid spending most of the report on background theory and procedure while leaving only a few paragraphs for interpretation and evaluation.
What counts toward the 3,000-word limit?
The current guide states that the following do not count toward the maximum:
Charts and diagrams
Data tables
Equations, formulas, and calculations
Citations and references, including parenthetical citations, numbered citations, footnotes, and endnotes
Bibliography
Headers
Ordinary explanatory prose does count, including text written in bullet points. Do not place paragraphs of analysis inside a table merely to reduce the declared word count. Table contents should genuinely function as data, concise methodological information, or structured comparison rather than disguised continuous writing.
The following information should appear at the start of the report:
Title of the investigation
IB candidate code
Candidate codes of group members, if applicable
Declared word count
A cover page and contents page are not required. Appendices should not contain evidence essential to assessment, since assessors are not expected to search outside the main report for your method, calculations, analysis, or evaluation. The RevisionDojo guide to IA word-count management can help when editing an overlength draft.
Recommended IB Chemistry IA structure
The following outline is not an official mandatory template. It is a practical structure that follows the current criteria and keeps the report below 3,000 words.
Recommended section
Suggested words
Criterion supported
Research question and scientific context
300--450
Research design
Variables and methodological considerations
250--350
Research design
Materials, safety, and method
350--500
Research design
Data collection and processing
650--800
Data analysis
Interpretation of results
250--350
Data analysis
Conclusion
300--400
Conclusion
Evaluation and improvements
450--600
Evaluation
Suggested working total
2,550--3,000
All criteria
These are planning ranges, not IB requirements. Aim for approximately 2,700 to 2,900 words so that later corrections do not push the report over the limit.
Research question and scientific context
Begin with a concise introduction explaining the chemical system, the relevant theory, and why the relationship is scientifically meaningful. Include only background needed to understand the investigation and predict or interpret its outcome.
State a focused research question that identifies:
The independent variable, preferably with its range and units
The dependent variable and how it will be measured or calculated
The chemical system or reaction
Relevant fixed conditions where they define the investigation
For example: “How does temperature from 298 K to 318 K affect the rate constant for the reaction between sodium thiosulfate and hydrochloric acid, determined from the time required to reach a fixed turbidity threshold?” This is stronger than “How does temperature affect reaction rate?” because it makes the variables and measurement approach explicit.
A hypothesis may help organize your reasoning, but it is not a separately assessed requirement. If you include one, justify it using chemical theory rather than writing an unsupported prediction.
Variables and methodological considerations
Identify the independent, dependent, and important controlled variables. For each major control, explain how it was controlled and why variation would influence the result. A list that merely labels temperature, pressure, or concentration as “controlled” does not demonstrate effective experimental design.
Explain important choices such as the variable range, number of intervals, number of repeats, measuring instrument, concentration, database, or model. These decisions should be appropriate for answering the research question and realistic within available time and equipment. RevisionDojo's guide to designing effective science IA experiments provides further planning questions.
Materials, safety, and method
List relevant apparatus with capacities, precision, or measurement uncertainty where appropriate. Include chemical names, concentrations, and quantities so that another student could reproduce the investigation.
Write the method in a logical sequence and include details that affect validity, reliability, and safety. Address chemical hazards, risk controls, waste disposal, and environmental or ethical considerations where relevant. The method should describe what you actually did, including justified modifications made after preliminary trials.
Data collection, processing, and presentation
Present quantitative raw data in clearly labelled tables. Headings should include the measured quantity, unit, and uncertainty where applicable, while decimal places should reflect instrument precision. Record useful qualitative observations separately rather than converting interpretations into supposed raw data.
Show how the raw measurements were transformed into quantities that answer the research question. Depending on the investigation, this may include means, rates, equilibrium constants, percentage yields, standard deviations, calibration relationships, gradients, or propagated uncertainties. Include at least one clear sample calculation for each significant type of processing.
Graphs should have descriptive titles, labelled axes with units, appropriate scales, and suitable best-fit lines or curves. Add uncertainty bars when they communicate measurement uncertainty or variation, but do not use a statistical technique merely because it appears sophisticated. The RevisionDojo Chemistry data-analysis guide explains tables, significant figures, uncertainty processing, and graphs in more detail.
Interpretation of results
Explain the chemical meaning of the processed data. Discuss patterns, gradients, mathematical relationships, anomalies, variability, and whether uncertainty affects the strength of the apparent trend.
Do not simply repeat values already visible in a table. A useful analytical statement combines numerical evidence with interpretation, such as: “Increasing temperature from 298 K to 318 K increased the calculated rate constant from X to Y, consistent with a larger proportion of collisions exceeding the activation energy.”
Conclusion
Answer the research question directly and support the answer using specific processed results, uncertainties, trends, or statistical evidence. The conclusion must follow from the analysis rather than introduce new calculations.
Connect your result to accepted scientific context, such as a theoretical model, published value, or credible literature relationship. Explain agreements and differences rather than stating only that your result was “close” to an accepted value. Use a traceable citation for the comparison.
Evaluation and improvements
Identify specific methodological weaknesses and limitations, then explain their likely effects on the data or conclusion. Distinguish systematic effects, which may shift results consistently, from random variation, which affects precision and repeatability.
Link every important limitation to a realistic improvement:
Weak evaluation
Stronger evaluation
Human error affected the result.
The subjective visual endpoint produced inconsistent reaction times, increasing random variation between repeats.
Use better equipment.
Replace the visual endpoint with a calibrated colorimeter recording absorbance at fixed intervals.
Do more trials.
Increase repeats from three to five at each temperature to produce a more reliable mean and standard deviation.
Prioritize limitations according to their likely influence rather than producing a long list of minor issues. An extension may be included, but it should develop the chemistry logically and must not replace the required evaluation of the completed method.
Formatting conventions for a clear report
The IB does not mandate a particular font, citation system, or heading sequence for the Chemistry IA. Use a readable professional font, consistent spacing, numbered tables and figures, and one recognized referencing style throughout.
Useful conventions include:
Use SI units and correct chemical notation consistently.
Put units in table headings rather than repeating them in every cell.
Match decimal places to instrument resolution.
Define symbols before using them in calculations.
Number equations when referring to them later.
Place tables and graphs near the discussion that interprets them.
Refer to every figure or table in the text.
Keep screenshots, decorative photographs, and repeated calculations to a minimum.
For models of different approaches, consult the RevisionDojo Chemistry IA examples. Use exemplars to study organization and evidence, not to copy topics, wording, data, or analysis.
Common structural mistakes
The most frequent problems are not unusual fonts or missing decorative pages. They are failures to allocate space according to the assessment criteria.
Avoid these mistakes:
Writing an extensive textbook-style introduction unrelated to the research question
Giving a recipe-like method without justifying major design choices
Omitting raw data, measurement uncertainties, or sample calculations
Describing a graph without interpreting its chemical meaning
Making a conclusion without numerical evidence or scientific comparison
Listing vague “human errors” without explaining their direction or magnitude
Suggesting improvements that do not address the identified limitations
Hiding essential information in appendices
Using the pre-2025 five-criterion rubric
Before submission, compare the report with the current RevisionDojo IB Chemistry IA checklist. Jojo AI and the IB Chemistry IA Grader can help identify missing criterion evidence, but all submitted wording, reasoning, and interpretation must remain your authentic work and follow your school's academic-integrity guidance.
Conclusion
An effective IB Chemistry IA structure follows the logic of scientific inquiry: establish a focused question, justify a reproducible method, process and interpret relevant data, reach an evidence-based conclusion, and evaluate the method precisely. The report must remain within 3,000 words, but excluded data tables, equations, calculations, citations, and bibliography allow you to present evidence efficiently.
Treat the suggested word allocations as planning guidance rather than fixed requirements. RevisionDojo's Chemistry IA guide, exemplars, checklist, and Jojo AI feedback tools are most useful when applied criterion by criterion while revising your own original investigation.
Daniel holds an MSc in Chemistry from Imperial College London and has taught IB Chemistry for over 20 years, including as Head of Chemistry. His focus is on building the conceptual understanding behind each equation rather than rote recall.
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