25 Killer IB Chemistry IA Ideas for Top Marks

The IB Chemistry Internal Assessment (IA) is more than just a lab report; it’s your chance to dive into a chemical investigation that genuinely interests you, showing off your scientific skills and critical thinking. As former IB grads and expert tutors, we know that a great topic and careful work are your secret weapons for hitting those top marks.

This guide will give you the inside scoop, with a list of practical, experiment-friendly IA ideas and the strategies you need to nail the assessment criteria.

By using this guide, you will be able to:

• Discover 25 unique and practical IB Chemistry IA ideas, chosen for their potential to give you great data and deep analysis.
• Understand the latest IB Chemistry IA assessment criteria, giving you a clear roadmap of what examiners are looking for.
• Master research design, including how to create a killer research question, identify variables, and design a solid method.
• Learn best practices for data collection and processing to ensure your results are accurate, reliable, and meaningful.
• Identify and avoid common mistakes that often trip students up, protecting your marks and boosting your confidence.

The Foundation: Understanding the IB Chemistry IA

Your Internal Assessment (IA) is worth a hefty 20% of your final IB Chemistry grade, for both SL and HL. As of May 2025, it’s called a "Scientific Investigation" with a 3,000-word limit. It’s marked out of 24, split across four key criteria:

1. Research Design (6 marks): This is all about your research question, background theory, methodology, and safety/ethical considerations. Is your plan solid?
2. Data Analysis (6 marks): How well do you record, process, and present your quantitative and qualitative data? It's about making sense of your results.
3. Conclusion (6 marks): Do you interpret your data correctly? Does your conclusion answer your research question and link back to scientific theory?
4. Evaluation (6 marks): Here you reflect on the strengths and weaknesses of your experiment. What were the limitations, and how could you improve it?

25 Killer IB Chemistry IA Ideas

Here are 25 practical ideas to get you started. Remember, the goal is to refine one of these into a specific, focused research question you can realistically investigate in your school lab.

Chemical Kinetics

1. Effect of Temperature on Reaction Rate: Investigate how temperature changes the rate of the iodine clock reaction.
   • Variables: Independent: Temperature (°C); Dependent: Time for colour change (s).
2. Catalyst Concentration and Reaction Rate: Examine how varying the concentration of a catalyst (like manganese dioxide) affects the decomposition rate of hydrogen peroxide.
   • Variables: Independent: Catalyst concentration (mol dm⁻³); Dependent: Volume of oxygen produced over time (cm³ s⁻¹).
3. Surface Area and Reaction Rate: Study how the surface area of a solid (e.g., marble chips in different sizes) influences its reaction rate with an acid.
   • Variables: Independent: Surface area (powder vs. small chips vs. large chips); Dependent: Volume of CO₂ produced over time (cm³ s⁻¹).
4. pH and Enzyme Activity: Investigate how pH affects the rate of an enzyme-catalyzed reaction, like amylase breaking down starch.
   • Variables: Independent: pH of the buffer solution; Dependent: Time for starch to disappear (s), measured with iodine.
5. Ionic Strength and Reaction Rate: Explore how adding an inert salt to a solution affects the rate of a reaction between two ions.
   • Variables: Independent: Concentration of an inert salt (e.g., NaCl); Dependent: Reaction rate.

Thermochemistry & Energetics

6. Enthalpy of Combustion of Alcohols: Determine how the chain length of primary alcohols (methanol, ethanol, propan-1-ol, etc.) affects their enthalpy of combustion.
   • Variables: Independent: Type of alcohol; Dependent: Temperature change of water (ΔT) in a simple calorimeter.
7. Enthalpy of Neutralization: Compare the enthalpy change of neutralization for a strong acid-strong base reaction versus a weak acid-strong base reaction.
   • Variables: Independent: Strength of the acid/base; Dependent: Temperature change (ΔT) in a calorimeter.
8. Enthalpy of Dissolution: Investigate how the initial temperature of water affects the enthalpy of dissolution for a salt like ammonium nitrate.
   • Variables: Independent: Initial water temperature (°C); Dependent: Final temperature change (ΔT).
9. Hess's Law Verification: Use calorimetry to measure the enthalpy changes for a series of reactions that can be summed up to verify Hess's Law.
   • Variables: Independent: Reaction pathway; Dependent: Enthalpy change (ΔH).
10. Specific Heat Capacity of Metals: Determine and compare the specific heat capacities of different metals using calorimetry.
    • Variables: Independent: Type of metal; Dependent: Temperature change of water (ΔT).

Acid-Base Chemistry

11. Antacid Effectiveness: Compare how effective different commercial antacid tablets are at neutralizing a simulated stomach acid (HCl).
    • Variables: Independent: Brand of antacid; Dependent: Volume of HCl neutralized (cm³) determined by back-titration.
12. Vitamin C Content in Juices: Determine the concentration of ascorbic acid (Vitamin C) in different fruit juices using an iodometric titration.
    • Variables: Independent: Type of fruit juice (e.g., fresh vs. packaged); Dependent: Volume of iodine solution required (cm³).
13. Acidity of Coffee: Investigate how the brewing time or grind size affects the titratable acidity of coffee.
    • Variables: Independent: Brewing time (min) or grind size; Dependent: Volume of NaOH required for titration (cm³).
14. Buffering Capacity of Sports Drinks: Compare the ability of various sports drinks to resist changes in pH.
    • Variables: Independent: Brand of sports drink; Dependent: pH change after adding a set amount of acid/base.
15. Ethanoic Acid in Vinegar: Measure and compare the concentration of ethanoic acid in different types of vinegar (e.g., white, apple cider, balsamic).
    • Variables: Independent: Type of vinegar; Dependent: Volume of NaOH required for titration (cm³).

Electrochemistry

16. Electrolyte Concentration and Conductivity: Investigate how the concentration of an electrolyte (e.g., NaCl) affects the electrical conductivity of its solution.
    • Variables: Independent: Concentration of electrolyte (mol dm⁻³); Dependent: Conductivity (µS cm⁻¹).
17. Electrode Material and Galvanic Cell Voltage: Build several galvanic (voltaic) cells and determine how different combinations of metal electrodes affect the voltage produced.
    • Variables: Independent: Combination of metal electrodes; Dependent: Voltage (V).
18. Corrosion Rate of Iron: Investigate how salinity (NaCl concentration) affects the rate of rusting of an iron nail.
    • Variables: Independent: NaCl concentration (mol dm⁻³); Dependent: Mass loss of the nail (g) over time.
19. Electroplating Copper: How does current or time affect the mass of copper deposited onto an electrode during electrolysis of copper(II) sulfate solution?
    • Variables: Independent: Current (A) or time (s); Dependent: Mass of copper deposited (g).

Organic & Environmental Chemistry

20. Ester Synthesis Yield: Investigate how the carbon chain length of an alcohol affects the percentage yield when forming an ester with ethanoic acid.
    • Variables: Independent: Type of alcohol; Dependent: Yield of ester (g or %).
21. Saponification Rate: Study how temperature affects the rate of saponification (soap-making) of a specific vegetable oil.
    • Variables: Independent: Temperature (°C); Dependent: Time taken for the mixture to solidify or pH change.
22. Degradation of Bioplastics: Investigate how pH affects the degradation rate of a bioplastic (like PLA) in water.
    • Variables: Independent: pH of the solution; Dependent: Mass loss of the bioplastic (g) over time.
23. Aspirin Hydrolysis: Investigate how temperature affects the rate of hydrolysis of acetylsalicylic acid (aspirin) into salicylic acid.
    • Variables: Independent: Temperature (°C); Dependent: Concentration of salicylic acid produced (measured using colorimetry).
24. Water Hardness Analysis: Use EDTA titration to compare the total hardness (concentration of Ca²⁺ and Mg²⁺ ions) of different local water sources (e.g., tap water, bottled water, river water).
    • Variables: Independent: Water source; Dependent: Volume of EDTA solution required (cm³).
25. Phosphate Levels in Water: Compare the phosphate concentration in different water samples (e.g., from a pond, river, or tap) using colorimetry.
    • Variables: Independent: Water source; Dependent: Absorbance of light (related to phosphate concentration).

Mastering the Mechanics: How to Secure Top Marks

A great topic is just the start. The top marks are won in the details of your execution.

Crafting Your Research Question

Your Research Question (RQ) is the absolute backbone of your IA. A good RQ is focused, specific, and measurable.

Variables: The Heart of Your Experiment

You must clearly identify and control your variables. A table is a great way to present this.

• Independent Variable (IV): The one thing you deliberately change. You need at least five different values (e.g., five different concentrations) to see a clear trend.
• Dependent Variable (DV): The thing you measure that changes in response to the IV.
• Controlled Variables: Everything else that could possibly affect your results. You need to list them, explain why they matter, and state exactly how you will keep them constant.

Flawless Data Collection & Processing

• Go Beyond the Numbers: Your IA needs both quantitative (numerical) data and qualitative observations (e.g., "the solution turned cloudy," "fizzing was observed").
• More Data is Better: For each level of your IV, do at least three trials (five is even better). This proves your results are reliable and allows you to calculate averages and standard deviations.
• Uncertainty is a Must: Every measurement you take has an uncertainty. You must record these (e.g., ±0.05 cm³) and propagate them through all your calculations. This is a non-negotiable for a high score.
• Show Your Work: Include a clear sample calculation for each type of data processing you do (e.g., calculating a rate, finding an average, propagating uncertainty).

Avoiding Common Pitfalls

• Vague Methodology: Your method needs to be a step-by-step recipe that another student could follow perfectly. Include all chemical concentrations, equipment sizes, and specific instructions. Don't forget a risk assessment!
• Weak Background Theory: Your introduction needs to explain the chemistry behind your experiment. Why do you expect to see the results you're predicting? Cite your sources.
• Ignoring Errors: Your evaluation is critical. Don't just say "there was human error." Be specific. "The reaction time was hard to judge, leading to a random error of ±2 seconds." Then, suggest a specific, realistic improvement, like using a colorimeter.
• Conclusion Doesn't Match Data: Your conclusion must directly answer your RQ and be supported entirely by your processed data. Don't make claims your results can't back up.