What Makes a Good IB Chemistry Extended Essay Topic?

A good topic is narrow enough to investigate with real data, not a textbook summary. It needs a clear independent and dependent variable, equipment you can actually access, and a link to a named chemistry concept — kinetics, equilibrium, electrochemistry — so your analysis can go beyond description into genuine chemical reasoning.

Start with a variable you can change and a measurable outcome you can quantify — then name both explicitly. "Investigating the effect of catalyst concentration on the rate of decomposition of hydrogen peroxide, measured by volume of oxygen gas produced" beats "Why do catalysts work?" every time. Specificity is what examiners reward under Criterion A.

Narrower than you think. A whole reaction class ("esterification reactions") is too broad; one specific reaction with one manipulated variable and a defined range is right. If you can imagine writing 4,000 words on it without repeating yourself, you've probably got the scope correct — if you're already stuck at 1,500, it's too narrow.

Yes, but it's harder to score well. The IB allows non-experimental Chemistry essays (analysing published spectroscopic or computational data, for instance) but you still need original analysis, not a summary of sources. Most supervisors, myself included, recommend a hands-on lab investigation because it's easier to demonstrate personal engagement and rigorous data analysis.

It's marked out of 34 against five criteria: Focus and Method, Knowledge and Understanding, Critical Thinking, Presentation, and Engagement — the same criteria used across all subjects, applied through a chemistry lens. According to the IB, the current Extended Essay guide (first assessed 2023) weights Critical Thinking most heavily at 12 marks, which usually decides whether a chemistry essay reaches a B or an A.

4,000 words maximum, including the introduction, body, and conclusion — but excluding the abstract, contents page, footnotes, bibliography, and appendices. Examiners stop reading at word 4,000, so essays that ramble past the limit lose marks by omission, not penalty. Tight, well-planned chemistry essays usually land between 3,600 and 3,900 words.

Enough to run a meaningful uncertainty and trend analysis — in practice, at least 5 values of your independent variable with 3 repeats each (15 data points minimum), so you can calculate means, standard deviation, and propagate uncertainty properly. Thinner datasets make Criterion C (Critical Thinking) very hard to score well on.

Yes, in effect — the IB doesn't mandate the word "hypothesis" but a strong essay states a predicted outcome grounded in chemical theory before presenting results. This shows you understood the underlying chemistry going in, which examiners credit under Knowledge and Understanding, and gives your discussion section something concrete to evaluate against.

Most successful school-based chemistry EEs use standard equipment already in your lab: titration apparatus, colorimeters, pH probes, gas syringes, or a data logger. Before committing to a topic, check with your supervisor whether the specific equipment (a spectrophotometer, for example) is actually available — a brilliant topic that needs equipment your school doesn't have is a dead end.

Avoid anything requiring hazardous reagents your school won't approve (concentrated acids beyond lab-safe dilutions, toxic heavy-metal salts), anything already extensively published with no room for original variation, and anything relying on equipment you don't have access to. Also avoid topics so common that examiners have seen the exact same investigation dozens of times with identical conclusions.

Supervisors can discuss your topic choice, point out feasibility issues, and give feedback during three formal reflection sessions (part of the Reflections on Planning and Progress form, or RPPF), but they cannot correct drafts sentence-by-sentence or supply your research question. According to the IB, supervisors are limited to a maximum of roughly 3-5 hours of contact time in total.

Most schools launch the Extended Essay process in the first term of DP1, with topic selection due within weeks and data collection ideally finished before the end of that school year. Starting chemistry data collection early matters more than for essay-based subjects — you may need repeat trials if your first results are inconclusive, and lab access during DP2 exam term is limited.

Beyond your child's school supervisor, structured revision resources help most with the background chemistry needed to justify a topic choice and write a confident theory section — not with picking the topic itself, which must be genuinely their own. RevisionPrep's Revision Notes and Topical Worksheets on RevisionPrep are useful for shoring up the underlying content knowledge a strong EE analysis depends on.