IB Chemistry IA: 60+ Ideas, the Criteria, and How to Score 24

Most students pick their IB Chemistry IA topic backwards. They fall in love with an idea first, then find out the school lab can't measure it.

The students who score 22, 23 and 24 do it the other way round. They start with a measurement their lab can actually take well, then build a question around it.

This guide walks through the whole task. How the four criteria work. What examiners want in each one. How to write a research question that scores. And 60+ example research questions sorted by the 2025 syllabus themes.

Quick answer: The IB Chemistry IA (Internal Assessment) is one scientific investigation worth 20% of your final Chemistry grade at both Standard Level (SL) and Higher Level (HL). You choose your own research question, collect and process your own data, then write it up in a report of no more than 3,000 words. It's marked out of 24 across four equal criteria: Research design, Data analysis, Conclusion and Evaluation. The IB gives it 10 hours of class time. Your teacher marks it, and the IB moderates a sample from your school.

What is the IB Chemistry IA?

The IB Chemistry IA is a chemistry investigation you design yourself, written up as a report, worth 20% of your grade.

IA stands for Internal Assessment. "Internal" means your own teacher marks it, not an examiner in another country. The IB then re-marks a sample of reports from your school to check every school marks to the same standard. That check is called moderation.

The IB's official name for the task is the scientific investigation. It's the same task, with the same criteria and the same word limit, in Biology, Chemistry and Physics. Only the subject content changes.

You get one investigation. Not a folder of experiments. One research question, one method, one set of data, one report.

Since first assessment in 2025, the task has been simpler than the old version. There's no longer a mark for personal engagement, and no separate mark for communication. Four criteria, six marks each, 24 in total.

How much is the IB Chemistry IA worth?

The IB Chemistry IA is worth 20% of your final Chemistry grade at both SL and HL.

The other 80% comes from two written exams sat at the end of the course.

That 20% is the friendliest grade in the course. You pick the topic. You control the conditions. You can redo a data set that went wrong. Nobody is timing you in an exam hall.

Chemistry is graded out of 7. One grade band is often worth only a few percent overall, so a strong IA moves you more than students expect. Twenty-two out of 24 banks about 18 percentage points before you sit a single paper. Twelve out of 24 banks 10. That ten-point gap is a whole grade for many students.

It also lands early. Most schools finish the IA in Year 12 or early Year 13, months before exams. It's the one part of your grade you can fix while there's still time.

How is the IB Chemistry IA marked? The four criteria

The IB Chemistry IA is marked out of 24, split evenly across four criteria worth 6 marks each: Research design, Data analysis, Conclusion and Evaluation.

Every criterion is worth 25% of the IA mark. There's no mark for effort, neat formatting or how interesting your topic is. Write to hit these four things and you score.

Let's take them one at a time.

Criterion A: Research design (6 marks)

Research design asks how well you explain what you set out to measure and how you measured it.

To reach the top band (5–6 marks) your report has to do three things:

• State the research question inside a specific context. Name the independent variable, the dependent variable and the chemical system. Add background theory that actually matters to your question — not a general essay on kinetics.

• Explain your methodological choices, not just list them. Why that concentration range? Why five repeats? Why did you control temperature that way?

• Describe the method so precisely that another student could repeat it without asking you a question. Exact concentrations, exact volumes, exact equipment, exact steps.

You also have to name any safety, ethical or environmental issues. In Chemistry that usually means corrosive acids, flammable solvents, toxic salts and how you disposed of them. A one-line risk table is enough.

The most common way students lose marks here is a vague range. "Different concentrations of hydrochloric acid" is a 3-mark method. "0.25, 0.50, 0.75, 1.00 and 1.25 mol dm⁻³ hydrochloric acid, five trials each, all at 22 °C in a water bath" is a 6-mark method.

Criterion B: Data analysis (6 marks)

Data analysis asks whether you recorded, processed and presented your data in a way that answers your question.

Top-band work is clear and precise. Clear means someone can follow how you got from raw numbers to processed ones. Precise means you followed the conventions: correct units, sensible significant figures, labelled axes, uncertainties on every measured quantity.

This is where Chemistry IAs are usually won or lost. Three things do the damage:

• Significant figures. Your answer can't have more significant figures than your least precise measurement. A balance reading to 0.01 g does not give you a mass to five decimal places.

• Uncertainties. Every instrument has one. Write it down, then carry it through your calculation. Absolute uncertainties add when you add or subtract. Percentage uncertainties add when you multiply or divide.

• Raw before processed. Show the raw table first, then the processed table, then the graph. Examiners want to see the path.

Qualitative observations count too. Colour changes, precipitates, smells, temperature rises you noticed but didn't measure — record them. They often explain an odd data point later.

Criterion C: Conclusion (6 marks)

Conclusion asks whether you answered your own research question, and whether your answer matches accepted chemistry.

Two halves, both needed for full marks:

• A conclusion justified by your analysis. Not "the rate increased" but "the rate constant rose from 0.012 to 0.048 s⁻¹ across the 20 °C range, consistent with the gradient of my Arrhenius plot."

• A comparison with the accepted scientific context. Find a published value — a literature enthalpy of combustion, a textbook activation energy, a data booklet figure — and compare yours to it. Say by how much you differ, in percent, and why.

Cite the source properly. The IB says citations must be detailed enough for the source to be traceable. A bare URL isn't enough.

The trap here is the essay ending. Students write a beautiful paragraph about how much they learned. That earns nothing. Answer the question you asked, with your numbers, against a published number.

Criterion D: Evaluation (6 marks)

Evaluation asks you to judge your own method honestly and suggest fixes that follow from what went wrong.

The word that decides your band is specific. Generic weaknesses — "human error", "the equipment wasn't accurate", "I could have done more repeats" — sit in the 1–2 band. They apply to every experiment ever done, so they say nothing about yours.

Top-band evaluation does three things:

• Names a weakness that belongs to your method. "Heat loss from the open copper calorimeter meant my measured temperature rise was systematically low."

• Explains the relative impact. Which weakness mattered most? By roughly how much did it shift your result, and in which direction?

• Suggests improvements that are realistic and connected. A bomb calorimeter you'll never own is not realistic. A lid, a polystyrene cup and an extrapolated cooling curve are.

Ranking your weaknesses by size is the single fastest upgrade to this criterion. Most students list four problems as if they all mattered equally. They almost never do.

What makes a good IB Chemistry IA research question?

A good IB Chemistry IA research question names one independent variable, one dependent variable, and the exact chemical system you'll use.

Test yours against these five checks:

1. Can you measure the dependent variable in your school lab? If it needs a spectrometer your school doesn't own, it fails on day one.

2. Does the independent variable have at least five levels? Five points make a graph. Three make a rumour.

3. Can you repeat each level three to five times? Repeats are where uncertainty and reliability marks live.

4. Is there published chemistry to compare against? Criterion C needs a number to compare with.

5. Is it narrow? "How does temperature affect reaction rate" is a textbook chapter. "How does temperature (20–60 °C) affect the rate constant for the reaction between sodium thiosulfate and hydrochloric acid, measured by the disappearing-cross method?" is an IA.

A reliable template:

How does [independent variable, with range and units] affect [dependent variable, with units and how it is measured] in [the specific chemical system]?

Fill every bracket and Criterion A almost writes itself.

If you're stuck at the idea stage, Educifly's free IB IA topic generator throws subject-specific starting points at you until one fits your lab.

60+ IB Chemistry IA ideas and research questions

Here are 64 IB Chemistry IA ideas, sorted by the themes of the 2025 syllabus. All of them can be run with standard school equipment unless marked otherwise.

Treat these as starting points. Change the system, the range or the measurement method to make it yours — an identical copy of a published IA is an academic integrity problem, not a shortcut.

Structure 1: Particles, the mole and gases (8 ideas)

1. How does the temperature of a fixed mass of air (20–80 °C) affect its volume at constant pressure, and how closely does it follow Charles's law?

2. How does the molar mass of a volatile liquid measured by the gas syringe method compare with its accepted value, across five different alkanes?

3. How does the concentration of a copper(II) sulfate solution affect its absorbance, and how accurate is a calibration curve for finding an unknown?

4. How does the water of crystallisation in hydrated magnesium sulfate change with heating time (0–40 minutes) at a fixed temperature?

5. How does the percentage of calcium carbonate in different brands of antacid tablet compare, measured by back titration?

6. How does the purity of home-made copper(II) sulfate crystals change with the rate of cooling during crystallisation?

7. How does the empirical formula of magnesium oxide found by combustion compare with the theoretical formula, across five different masses of magnesium?

8. How does dissolved carbon dioxide content differ across five carbonated drinks, measured by mass loss over time?

Structure 2: Bonding, intermolecular forces and materials (8 ideas)

1. How does the number of carbon atoms in a straight-chain alcohol (C1–C5) affect its enthalpy of vaporisation, measured by cooling rate?

2. How does chain length in a homologous series of alcohols affect surface tension, measured by drop counting?

3. How does the polarity of a solvent affect the distance travelled by food dye pigments in paper chromatography?

4. How does the ratio of PVA glue to borax affect the viscosity of the resulting polymer slime?

5. How does the concentration of a cross-linking agent affect the water absorbency of a sodium polyacrylate hydrogel?

6. How does branching in isomeric alcohols (butan-1-ol vs 2-methylpropan-2-ol) affect boiling point?

7. How does the metal content of an alloy affect its density, compared across five coin types?

8. How does the concentration of calcium ions in tap water affect the volume of soap solution needed to form a lasting lather?

Structure 3: Periodicity and organic chemistry (8 ideas)

1. How does the position of a halogen in group 17 affect the rate of its displacement reaction with potassium halide solutions?

2. How does the group 1 or group 2 metal used affect the temperature change when its carbonate reacts with hydrochloric acid?

3. How does the length of the alkyl chain in an ester affect the yield of an esterification reaction under fixed conditions?

4. How does the concentration of sulfuric acid catalyst affect the percentage yield of ethyl ethanoate?

5. How does the ripeness of a banana affect the concentration of reducing sugars, measured by Benedict's test with colorimetry?

6. How does storage temperature affect the vitamin C content of orange juice over 10 days, measured by iodine titration?

7. How does the type of cooking oil affect its iodine number, measured by titration?

8. How does the caffeine content of five tea brands change with brewing time, measured by UV absorbance? (needs a UV spectrometer)

Reactivity 1: Energetics, fuels and Gibbs energy (10 ideas)

1. How does the number of carbon atoms in a straight-chain alcohol (C1–C5) affect its enthalpy of combustion, measured by calorimetry?

2. How does the concentration of hydrochloric acid affect the enthalpy change of neutralisation with sodium hydroxide?

3. How does the metal used (Mg, Zn, Fe, Sn, Pb) affect the enthalpy change of its displacement reaction with copper(II) sulfate?

4. How does the enthalpy of solution of five ammonium salts relate to their lattice enthalpies?

5. How does the mass of catalyst affect the total heat released in the decomposition of hydrogen peroxide?

6. How does the water content of a fuel affect its measured calorific value?

7. How does insulation type affect the percentage heat loss in a simple calorimeter, and how much does it change a measured enthalpy of combustion?

8. How does temperature affect the solubility of potassium nitrate, and what does the resulting van 't Hoff plot give for ΔH of solution? (HL)

9. How does temperature affect the equilibrium constant for the cobalt(II) chloride colour equilibrium, and what ΔH does that imply? (HL)

10. How does the choice of fuel among five candle waxes affect energy released per gram?

Reactivity 2: Kinetics and equilibrium (10 ideas)

1. How does temperature (20–60 °C) affect the rate constant for the sodium thiosulfate and hydrochloric acid reaction, and what activation energy does the Arrhenius plot give?

2. How does the surface area of calcium carbonate affect the initial rate of reaction with hydrochloric acid, measured by mass loss?

3. How does the concentration of hydrogen peroxide affect the initial rate of its catalysed decomposition, measured by gas volume?

4. How does the catalyst used (manganese(IV) oxide, potassium iodide, liver catalase) affect the activation energy of hydrogen peroxide decomposition?

5. How does pH affect the rate of the iodine clock reaction?

6. How does the concentration of potassium iodide affect the order of reaction in the persulfate–iodide clock reaction?

7. How does temperature affect the rate of decolourisation of potassium manganate(VII) by oxalic acid?

8. How does the concentration of ethanoic acid affect the equilibrium yield of ethyl ethanoate?

9. How does adding chloride ions shift the position of the iron(III) thiocyanate equilibrium, measured by colorimetry?

10. How does surface area of a zinc sample affect the volume of hydrogen produced per minute with dilute sulfuric acid?

Reactivity 3: Acids, bases, redox and mechanisms (12 ideas)

1. How does the concentration of a weak acid affect its measured pKa, across five ethanoic acid dilutions?

2. How does the buffering capacity of a carbonate buffer change with the ratio of acid to conjugate base?

3. How does the acid content of five brands of vinegar compare, measured by titration against standardised sodium hydroxide?

4. How does the citric acid concentration of five citrus fruits compare, measured by titration?

5. How does the antacid brand affect the volume of hydrochloric acid neutralised per gram?

6. How does the salt concentration in the bridge affect the cell potential of a zinc–copper voltaic cell?

7. How does the concentration of the electrolyte affect the mass of copper deposited during electroplating in a fixed time?

8. How does the metal pair chosen affect the standard cell potential of a voltaic cell, and how do the measured values compare with the data booklet?

9. How does temperature affect the rate of corrosion of iron nails in salt water over 14 days?

10. How does the concentration of chloride ions affect the rate of iron corrosion, measured by mass loss?

11. How does the leaving group in a halogenoalkane (Cl, Br, I) affect the rate of nucleophilic substitution with silver nitrate?

12. How does the structure of a halogenoalkane (primary, secondary, tertiary) affect the rate of hydrolysis, and what does that suggest about the mechanism?

Database and no-lab investigations (8 ideas)

Useful if your lab is closed, your school lacks equipment, or you're revisiting a failed data set late.

1. How does the number of carbon atoms in a homologous series affect boiling point, using published data across four different series?

2. How does electronegativity difference relate to bond enthalpy across 30 published diatomic and simple molecules?

3. How does atomic radius relate to first ionisation energy across periods 2 and 3, using data booklet values?

4. How do published Ka values relate to the structure of substituted benzoic acids?

5. How does the measured air quality index in five cities relate to their published nitrogen oxide emissions?

6. How does the pKa of a drug molecule relate to its published solubility, across 25 compounds?

7. How does lattice enthalpy relate to ionic radius across the group 1 halides, using Born–Haber data?

8. How does the octanol–water partition coefficient of a compound relate to its molar mass, across 30 published organic molecules?

Any idea marked (HL) uses HL-only content. SL students can still investigate the same system with an SL-level question.

How to structure your IB Chemistry IA report

There's no compulsory template, but this order maps cleanly onto the four criteria and keeps you inside 3,000 words.

Charts, diagrams, data tables, equations, calculations, citations, the bibliography and headers are all excluded from the 3,000-word count. Only your prose counts. That's more room than most students realise.

The IB also asks you to state four things at the start of the report: the title of the investigation, your IB candidate code, the candidate codes of any group members, and the number of words. You don't need a cover page or a contents page.

If you want a step-by-step walkthrough that applies across every subject, our guide on what an IB Internal Assessment is covers deadlines, weightings and marking across the whole Diploma.

Uncertainties in the Chemistry IA: the marks most students drop

Uncertainty work is the difference between a 4 and a 6 in Data analysis, and most Chemistry IAs handle it badly.

Start by writing down the uncertainty of every instrument you touch:

Then follow three rules:

• Adding or subtracting? Add the absolute uncertainties. A titre is a final reading minus an initial reading, so its uncertainty is double the single-reading value.

• Multiplying or dividing? Add the percentage uncertainties.

• Raising to a power? Multiply the percentage uncertainty by the power.

Put error bars on your graph. Draw a maximum and minimum gradient line. If your published comparison value falls inside that range, say so — it's strong evidence for Criterion C.

One more habit that earns marks: separate random error from systematic error in your evaluation. Random error is scatter, and repeats fix it. Systematic error is a consistent shift, and repeats don't fix it at all. Naming which type each weakness is shows the examiner you understand your own data.

Chemistry has a second uncertainty most students forget: the purity and age of the reagents. A bottle of hydrogen peroxide that's been open all year is not 20 volumes any more.

How to score 24 on the IB Chemistry IA

Full marks come from a boring topic done exceptionally well, not an exciting topic done roughly.

Six habits separate top scorers:

1. Pick a measurable system first. Choose the measurement your lab does best — titration, calorimetry, gas collection, colorimetry — then build the question around it.

2. Run a pilot. One quick trial before you commit tells you whether your range gives a readable trend. Fixing the range afterwards costs a week.

3. Take five levels and five repeats. Twenty-five data points is enough for real error bars and a defensible gradient.

4. Write the method the day you run it. Details you'll need for Criterion A vanish within 48 hours.

5. Find your published comparison value before you write the conclusion. If none exists, your topic is wrong for the IA.

6. Rank your weaknesses. Say which one shifted your result most, in which direction, and by roughly how much.

Your teacher is allowed to give feedback on one draft. They can point out where a criterion isn't met, but they can't edit the work for you. Use that one draft properly. Hand in a complete report, not a half-finished one, or you waste the only feedback you get.

If a specific criterion keeps costing you marks, a subject specialist can look at your draft against the descriptors. Educifly's IB Chemistry tutors work through the report criterion by criterion, and IA and EE coaching is available as an add-on to regular subject sessions.

Common IB Chemistry IA mistakes to avoid

These are the errors that show up again and again in moderated samples.

• A question that's too broad. "How does concentration affect rate?" has no system, no range and no measurement method.

• Only three data points. Not enough for a trend line or meaningful error bars.

• No repeats. Without repeats you can't estimate random uncertainty, which caps Criterion B.

• Copying a published IA. Moderators recognise well-known write-ups. It's an academic integrity breach, and the penalty is far worse than a low mark.

• Significant figures inherited from a calculator. Eight decimal places from a balance reading to 0.01 g is a precision error.

• No comparison to accepted chemistry. Criterion C caps at 2 marks without one.

• "Human error" in the evaluation. Generic, so it earns nothing.

• Ignoring safety and disposal. Chemistry IAs use corrosive and flammable substances. Leaving this out costs marks in Criterion A.

• Going over 3,000 words. Examiners stop reading at the limit, so anything past it is unmarked.

• Waiting for the deadline. IAs written in a rush read like it, and there's no time for a second data set.

How long does the IB Chemistry IA take?

The IB allocates 10 hours of the practical scheme of work to the scientific investigation, at both SL and HL.

Ten hours is class time for planning and lab work. Writing happens outside it. Most students spend 20 to 30 hours in total once drafting and processing are counted.

Those 10 hours sit inside a bigger practical programme: 40 hours at SL and 60 hours at HL. That covers regular practical work, the 10-hour collaborative sciences project, and the 10-hour scientific investigation that becomes your IA.

A realistic timeline looks like this:

Note the collaborative sciences project is a separate 10-hour task. It isn't graded and it isn't your IA. Don't confuse the two.

Chemistry IA vs Biology and Physics IA

The criteria are identical across the three sciences. What changes is where the marks get lost.

Chemistry sits in the middle. It's more repeatable than Biology, because reagents behave the same way every time. It's messier than Physics, because concentration, purity and temperature all drift while you work.

One Chemistry-specific advantage: the data booklet hands you published comparison values for free. Enthalpies of formation, electrode potentials, pKa values, bond enthalpies. Our guide to the IB Chemistry data booklet shows what's in each of its sections, and most of it works as the accepted value Criterion C asks you to compare against.

If you're taking two sciences, it's worth reading how the same four descriptors get judged in a different subject. The wording is identical. The examples examiners have in mind are not.

Where the IA fits in your IB Diploma

Each of your six subjects is graded out of 7, giving 42 points, and the core adds up to 3 more for a maximum of 45.

Your Chemistry IA is 20% of one of those seven-point scores. It won't decide your diploma on its own. But it's marked before exams, under conditions you control, and it can lift a subject by a full grade band.

Students who treat the IA as an early deposit on their final grade tend to walk into Paper 1 needing less from it. Students who leave it until three days before the deadline usually need a very good exam season to recover.

If you want your draft looked at against the four descriptors, book a free trial class and bring the report you've got.

Frequently asked questions about the IB Chemistry IA

What is the IB Chemistry IA?

The IB Chemistry IA is the Internal Assessment for the course: one scientific investigation that you design, run and write up yourself. The IB calls it the scientific investigation. It's worth 20% of your final Chemistry grade at both SL and HL, marked out of 24 across four criteria, with a maximum of 3,000 words.

How much is the IB Chemistry IA worth?

The IB Chemistry IA is worth 20% of your final Chemistry grade, the same at SL and HL. Paper 1 is worth 36% and Paper 2 is worth 44%. Because the IA is finished and marked months before exams, it's the most controllable 20% in the course.

How is the IB Chemistry IA marked?

It's marked out of 24 across four criteria worth 6 marks each: Research design, Data analysis, Conclusion and Evaluation. Your teacher marks it against the IB descriptors, then the IB moderates a sample of reports from your school to check the standard is the same everywhere.

How many words is the IB Chemistry IA?

The maximum is 3,000 words. Charts, diagrams, data tables, equations, formulas, calculations, citations, the bibliography and headers are all excluded from the count. Only your prose counts, so the effective limit is more generous than it first looks.

Is the IB Chemistry IA the same for SL and HL?

Yes. Same task, same four criteria, same 24 marks, same 3,000-word limit and the same 20% weighting. HL students often choose topics that use HL-only content, such as Gibbs energy or the Arrhenius equation, but that's a choice rather than a requirement.

What is a good IB Chemistry IA research question?

A good one names the independent variable with its range and units, the dependent variable with how you measured it, and the exact chemical system. For example: "How does temperature (20–60 °C) affect the rate constant for the reaction between sodium thiosulfate and hydrochloric acid, measured by the disappearing-cross method?"

Can I do a database Chemistry IA instead of an experiment?

Yes. A database or simulation investigation is allowed and can score full marks. You still need a clear research question, a described method for selecting and sampling the data, proper processing, and a conclusion compared with published chemistry. Explain why you chose that database and how you filtered it.

How many repeats do I need for the IB Chemistry IA?

There's no fixed rule, but five levels of the independent variable with three to five repeats each is the standard that supports good error bars and a defensible trend. Fewer than three repeats makes it hard to estimate random uncertainty, which caps Criterion B.

How do I handle uncertainties in the Chemistry IA?

Record the uncertainty of every instrument, then propagate it. Add absolute uncertainties when you add or subtract, add percentage uncertainties when you multiply or divide, and multiply the percentage by the power when you raise to a power. Show error bars on graphs and use maximum and minimum gradient lines where a gradient matters.

Can I collect data with other students?

You can collect data as a group if your teacher allows it, and the IB asks you to list the candidate codes of your group members at the start of the report. Everything after that must be individual: your own research question, your own processing, your own conclusion and your own evaluation. Sharing analysis is collusion, not collaboration.

How many drafts can my teacher check?

One. Your teacher can give oral or written feedback on a single draft, pointing out where criteria aren't met. They can't edit or rewrite it for you. Hand in a complete draft so that feedback is worth something.

When should I start my IB Chemistry IA?

Most schools start the IA late in Year 12 or early in Year 13. Give yourself at least eight weeks from choosing a topic to the final deadline. That leaves room for a pilot trial, a second data set if the first goes wrong, and a proper draft before feedback.

Educifly is a boutique online tutoring practice for IB, IGCSE, AP and SAT students. Our IB Chemistry specialists mark IA drafts against the official descriptors and work with students through the whole investigation, from research question to final evaluation.