A strong IB Chemistry IA research question identifies exactly what will be changed or compared, what will be measured, the chemical system being investigated, and, where useful, the measurement method. It must also lead to sufficient quantitative data and a conclusion grounded in chemical theory.
The research question is not an isolated sentence added after planning. It determines your variables, experimental range, controls, data processing, safety decisions, and ultimately what you can conclude. This article explains how to turn a broad topic into a focused, measurable question and how that decision affects the current Research Design criterion.
What the IB Chemistry scientific investigation requires
In the current course, first assessed in 2025, the Chemistry internal assessment is officially called the scientific investigation. According to the official IB Chemistry subject brief, it is an open-ended task in which students gather and analyse data to answer their own formulated research question.
The investigation accounts for 20% of the final Chemistry grade, is allocated approximately 10 hours, and produces an individual report with a maximum overall word count of 3,000 words. The current assessment model uses four criteria worth six marks each: Research Design, Data Analysis, Conclusion, and Evaluation.
The IB permits limited collaboration in small groups. Students may sometimes use similar methodologies, but the independent or dependent variable must differ and each student must collect unique data and submit an individual report. The IB Chemistry curriculum update also confirms that half of the available IA marks are allocated to Conclusion and Evaluation, making it especially important to choose a question that can support meaningful interpretation and criticism.
The anatomy of a strong IB Chemistry IA research question
A practical structure is:
How does [independent variable and range] affect [dependent variable with units] in [specific chemical system and conditions], as determined using ?
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[measurement or analytical method]
This is a planning framework, not an official sentence template. A good question can use different wording, including “What is the relationship between...” for a correlational or database investigation. What matters is that the question establishes a specific and appropriate chemical context.
Component
What it should establish
Example
Independent variable
What is deliberately changed
Temperature from 298 K to 338 K
Dependent variable
The quantitative outcome
Rate constant in s⁻¹
Chemical system
Substances and reaction being studied
Acid-catalysed hydrolysis of aspirin
Measurement method
How raw measurements produce the dependent variable
Colorimetry or titration
Scope
Range, intervals, concentrations, or sampling limits
Five temperatures at 10 K intervals
Relevant conditions
Factors needed to define or control the system
Constant pH, concentration, and total volume
You do not need to force every apparatus detail into the question. The make and model of a balance, the number of repeats, and the complete control procedure belong in the methodology. Include a method in the question when it clarifies what the measured quantity actually means.
From a vague topic to a precise question
Broad ideas such as acids, batteries, reaction rates, or vitamin C are starting points rather than research questions. Refinement requires you to select a chemical relationship and decide how it can be measured reliably.
Vague or weak question
Why it is weak
More precise version
How does temperature affect reaction rate?
No reaction, range, rate definition, or method is identified.
How does temperature from 298 K to 338 K affect the initial rate of the reaction between sodium thiosulfate and hydrochloric acid, determined from the time required to reach a fixed turbidity threshold?
Which antacid is best?
“Best” is subjective and brands introduce several uncontrolled differences.
How does the active ingredient in calcium carbonate, magnesium hydroxide, and sodium hydrogencarbonate antacid tablets affect acid-neutralising capacity in mol HCl g⁻¹, determined by back titration?
Does heating destroy vitamin C?
“Heating” and “destroy” are not operationally defined.
How does heating time from 0 to 30 minutes at 80.0 °C affect the ascorbic acid concentration of filtered orange juice in mol dm⁻³, determined by iodine titration?
How does concentration affect a voltaic cell?
The changing solution and electrode system are unclear.
How does Zn²⁺ concentration from 0.100 to 1.00 mol dm⁻³ affect the cell potential of a Zn/Zn²⁺
The improved versions are not automatically excellent investigations. For example, a student must still test whether the endpoint is objective, whether the proposed temperature can be maintained, and whether the expected change is larger than the measurement uncertainty.
A continuous independent variable, such as concentration, temperature, pH, or time, often supports stronger trend analysis than a set of unrelated categories. It may allow you to determine a gradient, reaction order, equilibrium relationship, or activation energy rather than merely compare means.
Choose a range broad enough to produce a detectable change but narrow enough for the same chemical process and method to remain valid. Use a pilot investigation to check suitable intervals, reaction times, solubility limits, instrument ranges, and safety constraints. Five evenly spaced values are often workable, but the IB does not prescribe a universal minimum number of values or repeats.
Define the dependent variable operationally
“Reaction rate,” “acidity,” and “efficiency” are concepts, not complete measurements. State what will be recorded and how it becomes the dependent variable. Reaction rate might be derived from gas volume per second, concentration change per second, or the reciprocal of the time to a reproducible endpoint.
Units and instruments should match the expected scale. If the anticipated mass change is 0.01 g, a balance reading only to 0.1 g cannot resolve it convincingly. Planning for precision at the research-question stage prevents a dataset dominated by instrumental uncertainty.
Identify controls through chemical reasoning
Controlled variables should be selected because they could affect the dependent variable, not because a generic checklist says to include them. In a kinetics investigation, concentration, temperature, catalyst quantity, surface area, mixing, and total volume may alter collision frequency or the reaction pathway. In electrochemistry, electrode area, ion concentration, temperature, salt bridge composition, and measurement time may influence cell potential.
For each important control, state why it matters and how it will be controlled. The RevisionDojo guide to designing a science IA experiment provides a useful planning sequence for connecting the question, variables, controls, and data collection.
Build chemical rationale into the question and context
A research question becomes chemically meaningful when a model or principle predicts a relationship. Examples include:
Collision theory and the Arrhenius equation for temperature and reaction rate.
Le Châtelier’s principle and equilibrium expressions for changes in equilibrium position or constant.
The Nernst equation for ion concentration and electrochemical potential.
Intermolecular forces for boiling point, solubility, or partitioning trends.
Acid-base equilibria for buffer capacity, pH, and neutralisation.
Redox stoichiometry for determining analyte concentration by titration.
The background section should explain only the theory needed to justify the predicted relationship, variable range, controls, and processing method. For instance, if temperature is varied to determine activation energy, explain why plotting ln k against 1/T should produce a linear relationship and how the gradient relates to activation energy. The official IB Chemistry data booklet contains relevant equations and constants, but you must still explain their application to your investigation.
How the research question drives Research Design marks
Research Design assesses more than the wording of the question. It evaluates how effectively you communicate the purpose and practice of the methodology used to address it. A high-level response places the question in a specific and appropriate context, explains methodological decisions for collecting relevant and sufficient data, and presents a reproducible method.
The research question drives each of those elements:
Context: The substances, reaction, variables, and relevant theory establish what is being investigated.
Data relevance: Every measurement must contribute directly to answering the question.
Data sufficiency: The range, intervals, repeats, precision, and sampling frequency must support a defensible trend.
Controls: The proposed causal relationship determines which competing variables require control.
Reproducibility: The method must specify how the variables are changed, measured, and controlled.
Safety and environmental decisions: The selected chemicals, concentrations, temperatures, and disposal route determine the risks.
A beautifully phrased question cannot compensate for an unreproducible method. Conversely, a detailed procedure cannot fully rescue a question that lacks clear variables or a coherent chemical purpose. Use the current RevisionDojo IB Chemistry IA guide alongside your teacher’s copy of the official subject guide to check the criterion language.
Test feasibility before finalising the question
Carry out a short pilot before committing to your final wording. The pilot should answer practical questions:
Does the reaction produce a measurable change within the available lesson time?
Is the endpoint objective and repeatable?
Does the equipment have suitable resolution and range?
Can the important control variables be maintained?
Can enough data be collected safely with available chemicals?
Is the planned processing capable of answering the question?
Revise the question if the pilot reveals that the dependent variable cannot be measured reliably. Changing from “time until a cross disappears” to colorimeter absorbance, for example, may reduce observer subjectivity if suitable equipment is available. RevisionDojo’s methodology-writing guide can then help you turn the tested design into a reproducible procedure.
Common research-question mistakes
Investigating several independent variables at once: This makes causal interpretation and control difficult. Keep one principal relationship unless a more complex design is scientifically justified and manageable.
Using categories without chemical justification: Comparing brands often confounds composition, tablet mass, coatings, and manufacturing differences.
Naming a method without understanding it: A spectrophotometer does not automatically make an investigation sophisticated. You must justify wavelength, calibration, concentration range, and relevant assumptions.
Choosing a predetermined demonstration: Simply confirming that concentration increases rate may leave little analytical depth unless you determine a rate law or test a quantitative model.
Ignoring uncertainty until data analysis: Precision determines whether the proposed effect can be distinguished from measurement variation.
Making the question excessively long: Include details that define the investigation, then place procedural specifics in the method.
The RevisionDojo Chemistry IA topic collection is useful for generating possibilities, but every idea must be adapted to your laboratory, interests, and available measurement techniques.
A final research-question checklist
Before obtaining teacher approval, confirm that you can answer yes to each question:
Does the question identify an independent variable and dependent variable, or two correlated variables?
Is the chemical system unambiguous?
Can the dependent variable be measured quantitatively with appropriate units?
Is there relevant chemical theory predicting or explaining the relationship?
Is the range likely to produce detectable but manageable changes?
Can important variables be controlled consistently?
Will the design generate enough relevant data for processing and uncertainty analysis?
Are the chemicals, quantities, temperatures, and disposal procedures safe and realistic?
Can the question be answered within the available time and 3,000-word report limit?
Conclusion
A strong IB Chemistry IA research question combines focus, measurable variables, chemical context, a workable analytical method, and a defensible scientific rationale. Its quality matters because it determines what data you collect, what controls you need, what analysis is possible, and how convincingly you can answer and evaluate the investigation.
After piloting the method, revise the wording so it accurately reflects what you will investigate rather than what you originally hoped to investigate. RevisionDojo’s IA guide, Chemistry exemplars, and IA Feedback with Jojo AI can help you test clarity and identify design gaps, while your Chemistry teacher should confirm laboratory feasibility and safety before data collection begins.
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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