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The Evaluation section of your IB Chemistry IA demonstrates your ability to think critically about your experiment. In this section, you should assess the quality of your results, identify limitations, consider sources of error, and propose meaningful improvements. This post will outline some key things to keep in mind when writing the evaluation of your IB Chemistry IA.
IB Chemistry IA Evaluation
Highlight the strengths
A strengths section in the evaluation allows you to demonstrate aspects of the investigation that worked well. This may include effective control of variables, consistent measurement techniques, or appropriate use of equipment with sufficient resolution. For example, an IA about using titrations to measure the vitamin C concentration in orange juice could say, “Using a 25.00 mL burette with a 0.05 mL resolution significantly increased the accuracy of the titration readings.” Highlighting the strengths of your investigation shows awareness of what gave your results credibility and why your experimental method was scientifically sound. For a good example of how to highlight strengths, see this IA.
Explain the weaknesses and suggest improvements
Your evaluation should also address experimental limitations that reduced reliability or accuracy, and offer improvements to address them. You should avoid using vague statements like “human error affected the results” and should instead identify specific procedural or equipment-related issues. For example, an IA discussing the effect of temperature on ester hydrolysis could say, “A major weakness was the fluctuating temperature of the water bath, which altered reaction rate measurements; using a thermostatically controlled bath instead would help maintain a constant temperature.” Each weakness must identify a targeted improvement that would increase the precision or accuracy if the experiment were to be repeated in future. A good example can be seen here.
Discuss all types of errors
The discussion about experimental limitations should reflect random, systematic, and human errors wherever possible. You should explain how each type of error influenced your results. Random errors may arise from minor measurement fluctuations, while systematic errors could stem from impure reagents or miscalibrated instruments. For example, the evaluation for an IA about measuring the percentage of calcium in chalk could say, “A systematic error occurred because the analytical balance consistently read 0.003 g higher, shifting all mass-dependent calculations.” A thorough error discussion shows understanding of where uncertainty entered your experiment and how it affected your final results. A good example of when a student discussed various types of errors can be found here and here.
Provide some extensions to the experiment
Provide some extensions that demonstrate higher-level thinking by proposing broader applications related to your IA topic. These should build on your findings and explore related variables or improved methodologies. For example, an IA about a colourimetric titration could say, “An extension could involve using UV-Vis spectroscopy to measure reaction progress continuously and compare its precision to the manual sampling method used in this experiment.” Including thoughtful extensions shows that you understand the larger scientific context and can provide relevant ideas on how the research could be further explored. A good example of extensions can be found here and here.
We hope this post has helped you learn more about how to write an IB Chemistry IA evaluation. For more useful materials associated with the IB, check out the wide variety of IA, EE and TOK exemplars available at Clastify and other guides available on our blog.
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