Chemistry IA Ideas Examiner-ranked topics · 2026
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24 IB Chemistry IA ideas that score highly

Experienced IB examiners's pick of Chemistry Internal Assessment topics for 2026 — sorted by syllabus area, each with the variables, the technique and why it scores. Choose one, then plan it in our examiner-written Chemistry IA writing frame.

What makes a Chemistry IA topic score? A genuine chemical reaction at its heart (a purely physical change is not a valid Chemistry IA); a clearly named independent variable (with range and units) and dependent variable (with how it's measured); feasibility with school apparatus; and enough quantitative data to process with uncertainty and graph. Every idea below is built to tick all four — phrase yours as "How does … affect …?".

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ENERGETICS & THERMOCHEMISTRY

Calorimetry investigations are reliable, data-rich and easy to compare against literature values.

1 · How does the carbon-chain length of an alcohol affect its enthalpy of combustion?

IV: chain length (methanol → pentanol) · DV: ΔHc from calorimetry · Technique: spirit-burner calorimetry

A classic for a reason: a clean linear trend, a clear comparison to data-book ΔHc values (the gap drives your evaluation: incomplete combustion, heat loss), and rich uncertainty work.

🔥 calorimetry★ data-richvs literature

2 · How does the concentration of a salt affect its enthalpy change of solution?

IV: concentration / identity of salt · DV: ΔHsol · Technique: polystyrene-cup calorimetry

Lets you discuss lattice enthalpy vs hydration enthalpy in the conclusion — strong syllabus links and a clear endothermic/exothermic story.

🔥 calorimetrytheory links

3 · How does the strength of an acid–base pair affect the enthalpy of neutralisation?

IV: strong/weak acid & base pairs · DV: ΔHneut · Technique: calorimetry

The weak-acid dip (energy used to dissociate) gives a genuinely interesting result to explain — well above a generic "does it get hot" study.

🔥 calorimetryacids/bases

KINETICS — RATES OF REACTION

Rate studies give you a gradient, an order or an activation energy — perfect for graphical analysis and error bars.

4 · How does temperature affect the rate of the sodium thiosulfate–HCl reaction, and the activation energy?

IV: temperature · DV: rate = 1/t (the "disappearing cross") · Technique: turbidity timing → Arrhenius plot

An Arrhenius treatment lets you extract an activation energy and compare it to literature — sophisticated processing that reaches the top of Data Analysis.

⏱ ratesArrhenius / Ea★ data-rich

5 · How does acid concentration affect the rate of reaction of calcium carbonate with HCl?

IV: [HCl] · DV: rate from gas volume or mass loss · Technique: gas syringe / mass-loss balance

Determine the order with respect to acid from a rate–concentration graph — a stronger analysis than a single rate comparison.

⏱ ratesorder of reaction

6 · How does catalyst concentration affect the rate of decomposition of hydrogen peroxide?

IV: [catalyst] (e.g. MnO₂ or catalase) · DV: rate of O₂ evolution · Technique: gas collection over time

Clean gas-collection data and a clear catalysis story; with a biological catalyst it links to enzyme kinetics for the evaluation.

⏱ ratescatalysis

7 · How does the surface area of calcium carbonate affect reaction rate with acid?

IV: particle size (powder → chips) · DV: initial rate · Technique: gas syringe / mass loss

Feasible and reliable; push it above the basics by quantifying surface area rather than just "small vs large".

⏱ ratesaccessible

ACIDS, BASES & TITRATION

Titrations are precise, repeatable and produce small percentage uncertainties — examiner gold.

8 · How does storage time (or temperature) affect the vitamin C content of fruit juice?

IV: storage time/temp · DV: [vitamin C] · Technique: redox titration (DCPIP or iodometric)

A real-world hook, a clear degradation trend, and titration precision — consistently a high scorer.

🧪 titrationreal-world★ data-rich

9 · Determining and comparing the calcium content of milk brands by EDTA titration.

IV: milk brand/type · DV: [Ca²⁺] · Technique: EDTA complexometric titration

Complexometric titration is a step up in sophistication and gives tight, comparable data with labelled-value comparison.

🧪 titrationcomplexometric

10 · How does brewing time or temperature affect the acid content of tea or coffee?

IV: brew time/temp · DV: titratable acidity · Technique: acid–base titration / pH probe

Everyday context with a clean trend; pair with a colour/colourimeter measure for a richer dataset.

🧪 titrationreal-world

11 · Determining the percentage of acetylsalicylic acid in aspirin brands by back-titration.

IV: aspirin brand · DV: % active ingredient · Technique: back-titration

Back-titration shows real technique, and comparing to the stated dose gives a built-in accuracy check for the conclusion.

🧪 titrationback-titration

12 · How does cooking method affect the vitamin C retained in a vegetable?

IV: cooking method/time · DV: [vitamin C] · Technique: redox titration

Strong personal-interest angle and a clear, explainable trend (heat and water-solubility losses).

🧪 titrationreal-world

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REDOX & ELECTROCHEMISTRY

13 · How does temperature affect the EMF of a Daniell (zinc–copper) voltaic cell?

IV: temperature · DV: cell EMF · Technique: voltmeter / data logger

Links to the Nernst equation for a sophisticated conclusion; data-logging gives precise, repeatable readings.

⚡ electrochemNernst

14 · How does electrolyte concentration affect the mass of copper deposited during electrolysis?

IV: [CuSO₄] or current · DV: mass deposited · Technique: electrolysis + precise weighing

A direct Faraday's-law test with a clean linear relationship and small mass uncertainties.

⚡ electrochemFaraday

15 · How do salt concentration and pH affect the rate of corrosion (rusting) of iron?

IV: [NaCl] / pH · DV: extent of corrosion · Technique: mass change / colourimetric indicator

Real-world relevance and a redox story; control the time and surface area carefully for a clean trend.

⚡ redoxreal-world

EQUILIBRIUM

16 · How does temperature affect the position of the Fe³⁺/SCN⁻ equilibrium?

IV: temperature · DV: equilibrium colour / [FeSCN²⁺] · Technique: colourimeter / spectrophotometer

A quantitative Le Chatelier study (not just "it goes darker") using a calibration curve — high-level processing.

⚖ equilibriumcolourimetry★ data-rich

17 · Determining the equilibrium constant of an esterification and how temperature shifts it.

IV: temperature / mole ratio · DV: Kc · Technique: titration of the equilibrium mixture

Ambitious and rewarding — a genuine Kc determination demonstrates command of equilibrium for the top band.

⚖ equilibriumstretch

ORGANIC, ANALYTICAL & APPLIED

18 · How does the degree of unsaturation of cooking oils affect their iodine number?

IV: oil type · DV: iodine number · Technique: iodine/bromine titration

Connects structure (C=C bonds) to a measurable quantity — a clear, explainable comparison across brands.

🧪 titrationorganic

19 · How does temperature affect the rate of esterification (or hydrolysis of an ester)?

IV: temperature · DV: rate · Technique: titration of remaining acid over time

Combines organic chemistry and kinetics; gives an activation-energy extension if you take several temperatures.

organic⏱ rates

20 · Comparing the energy content of biodiesel and vegetable oil by calorimetry.

IV: fuel type · DV: energy released per gram · Technique: calorimetry

Topical sustainability angle with a measurable, comparable result and a strong evaluation about heat loss.

🔥 calorimetrysustainability

21 · How effectively do different antacid brands neutralise stomach acid?

IV: antacid brand · DV: moles of acid neutralised per gram · Technique: back-titration

Consumer-chemistry hook with a fair, quantitative comparison and clear method control.

🧪 titrationreal-world

22 · Determining water hardness across sources by EDTA titration.

IV: water source · DV: total hardness (ppm CaCO₃) · Technique: EDTA titration

Precise complexometric data with an environmental angle and easy comparison to published values.

🧪 titrationenvironmental

23 · How does pH affect the rate of enzymatic browning (or vitamin degradation) in fruit?

IV: pH · DV: rate of colour change · Technique: colourimeter

A colourimetric kinetics study with a clear optimum to find and explain — visually engaging, quantitatively solid.

colourimetryreal-world

24 · Determining and comparing the sugar content of soft drinks.

IV: drink brand · DV: [sugar] · Technique: density/refractometry or an enzymatic/Benedict's method

Accessible data with a strong consumer hook; choose a quantitative method (not just Benedict's colour) to reach the higher bands.

analyticalreal-world

From a topic to a top-band IA

An idea is the easy part — the marks are in how you build it. The Chemistry IA is scored out of 24 across four equal criteria: Research Design, Data Analysis, Conclusion and Evaluation. Whichever topic you pick, the same moves win: a focused research question with named variables, a method developed through trials, data processed with absolute and percentage uncertainty, a graph with error bars and a gradient, a conclusion justified against literature, and an evaluation that weighs your errors and proposes realistic improvements and extensions.

Build your chosen idea into a full IA

The examiner-written Chemistry IA writing frame takes you through every section with the rubric, worked examples and the traps that cost marks. Research Design is free — unlock Data Analysis, Conclusion & Evaluation to finish the whole investigation and export it to Word or PDF.

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Chemistry IA ideas — FAQ

What makes a good IB Chemistry IA topic?

A genuine chemical reaction at its heart (not a purely physical change), a clearly named independent variable with range and units, a dependent variable with how it's measured, feasibility with school apparatus, and enough quantitative data to process with uncertainty and graph. Phrase it as "How does … affect …?".

How many data points and repeats do I need?

At least five values of the independent variable across a sensible range, each repeated at least three times so you can take a mean, show error bars and judge reliability. A wide enough range to reveal a clear trend matters more than sheer quantity.

Can I just copy one of these ideas?

Use them as a launchpad, but make the investigation your own: narrow the research question, choose your own variable ranges, and develop the method through your own trials. That ownership is exactly what the Research Design and Evaluation criteria reward.

How do I turn the idea into a top-band IA?

Build it section by section in the free Chemistry IA writing frame — research question, variables, method, data with uncertainty, graphs with error bars, conclusion against literature, and an evaluation with realistic improvements and extensions.

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