Unit Overview
Practical and investigative skills
IB Chemistry HLΒ· 5 min read π n/a
1. Unit at a glance
Practical chemistry is the foundation of chemistry as an experimental science, and this unit builds transferable skills you will use for both exam questions and your mandatory internal assessment. The learning arc progresses logically from planning an experiment through processing data, analyzing error, drawing conclusions, and finally breaks down all IA requirements.
Each subtopic builds directly on the previous one: you cannot correctly analyze data without first designing a controlled experiment, and you cannot draw a valid conclusion without properly accounting for experimental uncertainty. These skills are applied across all other units of IB Chemistry.
The following subtopics make up this unit:
Experimental design
Learn to write testable research questions, control variables, and plan safe, appropriate experimental methods.
β β β± 8 min
Data collection and processing
Master recording qualitative/quantitative data, converting units, and processing raw data into usable results.
β β β± 7 min
Graphical analysis and error estimation
Construct meaningful graphs, propagate error, and calculate uncertainty in final experimental results.
β β β β± 10 min
Scientific reasoning and conclusion drawing
Evaluate whether data supports your hypothesis, and identify key limitations of your experimental design.
β β β β± 8 min
Internal assessment requirements
Break down IB's IA marking criteria, and learn how to structure your IA report for full marks.
β β β± 12 min
2. Common Pitfalls
Wrong move:
Confusing random error with systematic error when evaluating experiments
Why:
This leads to incorrect improvement suggestions, costing marks in both exams and the IA
Correct move:
Attribute inconsistent variation to random error (reduced by repeats) and consistent bias to systematic error (reduced by better calibration)
Wrong move:
Leaving multiple key variables uncontrolled in an experimental design
Why:
This makes it impossible to isolate the effect of the independent variable on your outcome
Correct move:
Explicitly list all controlled variables and describe how they are kept constant during the experiment
Wrong move:
Ignoring uncertainty when drawing conclusions from data
Why:
This can lead to false claims of trends or correlations that are not supported by your results
Correct move:
Always compare the magnitude of uncertainty to the size of your measured effect when concluding
3. Quick Reference Cheatsheet
Key Concept/Formula | Description |
|---|---|
Calculate percentage uncertainty for a single measurement | |
Total uncertainty = Sum of absolute uncertainties | Rule for combining uncertainty with addition/subtraction |
Total % uncertainty = Sum of individual % uncertainties | Rule for combining uncertainty with multiplication/division |
Independent variable | Variable intentionally changed in an experiment to test its effect |
Dependent variable | Variable measured to assess the effect of the independent variable |
Controlled variable | Variable kept constant to avoid confounding experimental results |
Random error | Unpredictable measurement variation, reduced by repeated trials |
Systematic error | Consistent measurement bias, reduced by improved equipment or procedure |
IA Criterion: Evaluation | Worth 6 marks, assesses your analysis of error and experimental limitations |
IA Criterion: Personal Engagement | Worth 2 marks, assesses your personal input and interest in your topic |
What's Next
Begin your study of this unit with the first subtopic on experimental design, which lays the foundation for all other practical skills you will build in this unit. Mastering this first topic will make it easier to understand subsequent concepts around data processing, error analysis, and internal assessment. Once you complete all subtopics in this unit, you are ready to move on to the next unit of IB Chemistry HL covering additional higher-level topics.