IB Chemistry Extended Essay: Guide for the 2027 Criteria
By Michael Thompson · Education Specialist; 10 years teaching the IB at Bromsgrove School · Published 4 October 2026 · Updated 6 October 2026
The IB chemistry extended essay is a 4,000-word independent research project assessed under five criteria totalling 30 marks, first examined in May 2027. If you are sitting the May 2027 session or later, this is the model that applies to you - the previous 34-mark model is used for the last time in the November 2026 session. Choosing a focused, testable research question is the single most important decision you will make, and it shapes every criterion from Framework to Reflection. This guide walks through the 2027 criteria, what each one demands in a chemistry context, how to choose and test a research question, and what to do this week to get started.
Key Takeaways
- 30 marks across five criteria: The updated assessment model - Framework (6), Knowledge and understanding (6), Analysis and line of argument (6), Discussion and evaluation (8), Reflection (4) - applies from May 2027 onwards.
- 4,000-word limit: The word count covers the introduction, body, conclusion and any quotations; the title page, contents page, references and bibliography sit outside this count.
- Three mandatory reflection sessions: The last session is a 20-30 minute viva voce with your supervisor, and you submit a 500-word reflective statement on the Reflection and Progress Form at the end of the process.
- Subject-focused or interdisciplinary pathway: You can write your chemistry EE on a single-subject basis or combine chemistry with another DP subject on the interdisciplinary pathway - both use the same five criteria.
- The EE is not your IA: The chemistry internal assessment is a separate scientific investigation of at most 3,000 words worth 20% of your subject grade; you cannot submit the same work for both.
- No grade boundaries yet: The IB has not published grade boundaries for the 30-mark scale; they will not be available until after the May 2027 session results on 6 July 2027.
In This Article
- What the IB Chemistry Extended Essay Is (and What It Is Not)
- The 2027 Assessment Criteria Explained
- How Each Criterion Works in a Chemistry Essay
- Choosing an IB Extended Essay Chemistry Topic and Research Question
- Structure, Format and IB Extended Essay Guidelines
- Common Mistakes to Avoid in a Chemistry Extended Essay
- What to Do Next
1. What the IB Chemistry Extended Essay Is (and What It Is Not)
The IB chemistry extended essay is a compulsory, independently researched piece of academic writing that sits at the core of the IB Diploma Programme. Per the IB's extended essay updates page, first assessment under the new criteria takes place in May 2027. Every DP student writes one, regardless of their subject choices.
You have two structural options. The subject-focused pathway ties the essay to one DP subject - for a chemistry EE, chemistry. The interdisciplinary pathway draws on two DP subjects together. Both pathways are assessed against exactly the same five criteria, so the choice of pathway does not give you a marking advantage either way.
One distinction that trips up students regularly: the EE is not your chemistry internal assessment (IA). The IA is a separate scientific investigation with a maximum written report of 3,000 words, worth 20% of your chemistry subject grade, and assessed entirely independently from the EE. The two pieces are designed for different purposes, and you cannot repurpose one as the other.
The EE does feed into your overall DP score. Completed alongside Theory of Knowledge, the two components together carry a combined maximum of 3 bonus points toward your DP total, as confirmed by the IB Extended Essay subject brief.
2. The 2027 Assessment Criteria Explained
The updated assessment model contains five criteria totalling 30 marks, as set out on the IBO's extended essay updates page. They are labelled Criterion A to E.
| Criterion | Name | Marks |
|---|---|---|
| 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 |
| Total | 30 |
Criterion D carries the most weight at 8 marks, which tells you something about where examiners expect the intellectual effort to show. A tidy experiment with weak evaluation will not score well.
The same five criteria apply in every subject and on both pathways (subject-focused and interdisciplinary). Subject-specific guidance for chemistry sits in the full EE guide on the IB Programme Resource Centre, which your supervisor or coordinator can access. Ask them for the sciences guidance, which includes chemistry examples, rather than working from general descriptions.
No grade boundaries for the 30-mark scale will be published until after the May 2027 results, which are due on 6 July 2027. Any boundary figures circulating before that date are unofficial estimates.
> Note on the previous model: November 2026 is the final session assessed on the old 34-mark framework. If you are sitting May 2027 or later, that model does not apply to you.
3. How Each Criterion Works in a Chemistry Essay
The five criteria are identical across every subject and both EE pathways: the IB EE subject brief says every extended essay, subject-focused or interdisciplinary, is assessed against common criteria. What changes in a chemistry essay is how each criterion is satisfied in practice.
Criterion A - Framework (6 marks). A focused, specific research question and a justified, replicable method are the structural backbone here. In chemistry this means your research question names the substances and the independent and dependent variables precisely, and your method gives enough detail, controlled variables included, for another student to replicate the experiment. Section 4 looks at the IB's own chemistry example and what it does and does not pin down. Vague questions score poorly on this criterion regardless of how strong the data are.
Criterion B - Knowledge and understanding (6 marks). Accurate use of chemical terminology, correct SI units, and relevant chemical theory must run consistently through the whole essay. Subscripts and superscripts in chemical formulae matter here - sloppy notation signals weak subject knowledge even when the underlying chemistry is sound.
Criterion C - Analysis and line of argument (6 marks). Systematic data analysis includes explicit attention to uncertainty and error - the same data-handling skills the Paper 1B data-based questions draw on. The argument must follow clearly from the evidence rather than from assertion.
Criterion D - Discussion and evaluation (8 marks, the highest-weighted criterion). This is where most marks are won or lost. Evaluating findings against the research question, and honestly discussing methodological limitations, are both required. A counter-intuitive point: acknowledging where your method fell short tends to score better than overselling results, because it demonstrates genuine scientific thinking.
Criterion E - Reflection (4 marks). This is assessed on the 500-word reflective statement you write on the Reflection and Progress Form (RPF) at the end of the process, after the three mandatory supervisor sessions. The statement draws on those sessions, so use them to think about how you are developing as a researcher, not just to report progress.
Subject-specific guidance on what the criteria mean for chemistry sits in the full EE guide on the IB Programme Resource Centre, available to teachers and coordinators. Ask your supervisor to share the relevant sections rather than relying on older or unofficial interpretations.
4. Choosing an IB Extended Essay Chemistry Topic and Research Question
A focused research question is the single biggest factor in whether a chemistry EE succeeds or collapses. The trap most students fall into is writing a question that is either too broad ("How do catalysts work?") or too vague to test experimentally. A strong chemistry question names the specific substance, fixes the key variables, and points clearly to a measurable relationship.
What a focused chemistry research question looks like
The IB EE subject brief gives a worked example for chemistry:
> 'What is the effect of manganese oxide versus copper (II) oxide in the catalysation of hydrogen peroxide at 21°C?'
Notice what the question does: it names both catalysts, names the substrate, locks in the temperature, and sets up a direct comparison. What it does not say is what will be measured (the rate of oxygen production, for example) or which other conditions, such as peroxide concentration and catalyst mass, are held constant; a one-line example leaves those to the method. In your own question, name the dependent variable too, and give oxidation states, as in manganese(IV) oxide. Named compounds, a named dependent variable and fixed conditions are the template to follow.
Fixing a key condition such as temperature in the question is fine, but the question's main job is to name the independent and dependent variables. The full list of controlled variables, with how you kept each one constant, belongs in your method.
Topic ideas written for this guide
These span the DP Chemistry syllabus strands of Structure and Reactivity (IB Chemistry subject brief):
- Reaction kinetics: How does the concentration of sodium thiosulfate affect the rate of its reaction with hydrochloric acid at 25°C, measured by turbidity change?
- Electrochemistry: How does the concentration of copper(II) sulfate electrolyte affect the current efficiency of copper deposition at the cathode, measured by the mass deposited at a fixed current and time and compared with the Faraday's-law prediction?
- Acid-base equilibria: How does the addition of sodium acetate in varying molar ratios to acetic acid affect the buffer capacity of the resulting solution, measured by pH change on addition of a fixed volume of HCl?
- Energetics: How does the chain length of primary alcohols (methanol to pentan-1-ol) affect the enthalpy of combustion per mole, determined by calorimetry?
- Spectroscopy: How does the concentration of copper(II) sulfate solution affect its absorbance at 635 nm, as measured by colorimetry, and does the relationship follow Beer-Lambert linearity?
Checklist: is your research question strong enough?
Before committing to a question, run it through these five tests:
- Named substance. Does the question name specific chemicals rather than generic categories? ("Iron(III) chloride" not "a metal salt.")
- Measurable variable. Is the independent variable something you can set precisely, and the dependent variable something an instrument can record with units?
- School-achievable scope. Can you repeat trials with available equipment, within standard lab sessions, without specialist facilities?
- Theory connection. Does the question tie to a concept in the Structure or Reactivity strands of the DP syllabus, so you can build genuine chemical analysis around the data?
- Enough to sustain 4,000 words. Is there sufficient underlying theory, methodology, data, and evaluative discussion to fill the word limit without padding?
On safety and ethics: any investigation involving hazardous reagents, biological materials, or human subjects needs careful planning before you begin. This is good scientific practice regardless of subject, and your supervisor should review your methodology early in the process.
5. Structure, Format and IB Extended Essay Guidelines
The IB subject brief sets out the required elements of the final submission:
- Title page
- Contents page
- Introduction
- Body
- Conclusion
- References and bibliography
The 4,000-word limit covers the introduction, body, conclusion, quotations and any footnotes that are not references. The title page, contents page, tables, equations and calculations, references, and bibliography sit outside the count. That distinction matters more than it looks: quotations count, so long quoted passages in the main text eat into your 4,000 words.
Reflection sessions and the RPF
Three formal reflection sessions with your supervisor are mandatory throughout the process. The third session is a viva voce, a conversation lasting about 20 to 30 minutes, used to check academic integrity and give you the chance to reflect on what the research taught you. At the end of the entire process, you submit a 500-word reflective statement on the Reflection and Progress Form (RPF). This is not a summary of your essay. It records how your thinking developed, not what you found.
Subject-specific structural guidance
The IB subject brief gives the universal framework. Subject-specific structural guidance, including any chemistry-focused requirements, sits in the full EE guide on the IB Programme Resource Centre. That guide is available to teachers and coordinators, not directly to students. Ask your supervisor or coordinator to share the sciences section, which covers chemistry, before you draft your methodology.
A note on examples
No essay has yet been marked in a real session under the 2027 criteria, so any marked sample essay you find online was marked on the old 34-mark model. Use it to judge quality, not to predict a mark out of 30.
6. Common Mistakes to Avoid in a Chemistry Extended Essay
A few errors appear so consistently that they are worth naming directly.
Submitting your chemistry IA as the EE. These are distinct components. The chemistry internal assessment is a written report of at most 3,000 words worth 20% of the subject grade, assessed separately from the EE. The EE is externally assessed, has a 4,000-word limit, and sits within the DP core. Recycling one as the other will be caught, and the purposes are genuinely different.
A research question that is too broad or too narrow. Four thousand words cannot sustain a question like "How do catalysts work?" It also cannot support one so obscure that it has no connection to chemical theory. The IB's own example in section 4 is a useful calibration point for scope: two specific catalysts, one substrate and a fixed temperature.
Thin uncertainty and error analysis. This feeds directly into Criterion C, Analysis and line of argument, worth 6 marks. Processed data without propagated uncertainties signals to the reader that the analysis is incomplete.
Underwriting the discussion section. Discussion and evaluation carries 8 marks, the highest of any criterion. A discussion that only summarises results rather than evaluating methodological limitations will not score well here.
Leaving reflection until submission week. The three formal reflection sessions are mandatory, and the 500-word reflective statement on the Reflection and Progress Form is assessed under Criterion E (4 marks). The sessions cannot be made up at the end, and the statement you write after them draws on them.
Applying the old marking model. The previous 34-mark framework does not apply to May 2027 onwards. The new model totals 30 marks across five criteria.
7. What to Do Next
The most useful thing you can do this week is ask your EE supervisor to share the sciences section of the full EE guide from the IB Programme Resource Centre, which covers chemistry alongside the other science subjects. That document is where subject-specific guidance for the 2027 criteria lives, and your supervisor or coordinator can access it directly.
While you wait, settle two decisions: which pathway you are following (subject-focused chemistry, or interdisciplinary combining chemistry with a second DP subject), and a working research question. A good first draft is narrow enough to test in a school lab and names specific substances, conditions, or variables.
Then book your first formal reflection session. Three are mandatory under the 2027 framework, so scheduling the first one early keeps the process on track rather than compressed at the end.
Contact your supervisor this week and confirm a date for that opening session.
FAQ
What is the extended essay in IB?
The Extended Essay is a compulsory, externally assessed component of the IB Diploma Programme core in which students produce an independent 4,000-word research essay; from May 2027 it is assessed on a 30-mark scale across five criteria and contributes to the combined EE and Theory of Knowledge bonus points.
How long is the IB extended essay?
The word limit is 4,000 words, covering the introduction, body, conclusion and any quotations; the title page, contents page, references and bibliography fall outside this limit.
What are the IB extended essay assessment criteria for 2025 and beyond?
From August 2025 (first assessment May 2027), the five criteria are: Framework for the essay (6 marks), Knowledge and understanding (6 marks), Analysis and line of argument (6 marks), Discussion and evaluation (8 marks), and Reflection (4 marks) - totalling 30 marks.
Can I use my IB chemistry internal assessment as my extended essay?
No - the chemistry internal assessment is a separate scientific investigation with a maximum written report of 3,000 words worth 20% of the subject grade, assessed independently; submitting the same work for both components is not permitted.
What is the IB extended essay grading scale for the new criteria?
The new model is marked out of 30; grade boundaries for this scale will not be published until after the May 2027 session results, expected 6 July 2027, so no boundaries can be quoted at this stage.
Where can I find IB extended essay examples for chemistry?
No essays have yet been marked under the 2027 criteria, so published examples follow the old model; the full EE guide on the IB Programme Resource Centre, which your supervisor or coordinator can access, includes chemistry example research questions and guidance for the sciences.
References
- DP extended essay updates - International Baccalaureate - https://www.ibo.org/university-admission/latest-curriculum-updates/dp-extended-essay-updates/
- Diploma Programme Subject Brief: Extended essay, first assessment 2027 (International Baccalaureate Organization, 2024) - https://www.ibo.org/globalassets/new-structure/university-admission/pdfs/ee_subjectbrief_en.pdf
- Diploma Programme Subject Brief - Sciences: Chemistry, first assessment 2025 (International Baccalaureate Organization 2022) - https://www.ibo.org/globalassets/new-structure/recognition/pdfs/dp_sciences_chemistry_subject-brief_jan_2022_e.pdf