Unit Overview

Practical and Investigative Chemistry

IB Chemistry SL· 5 min read 📊 n/a

1. Unit at a glance

This unit builds the scientific inquiry skills you need to complete your IB Chemistry SL internal assessment (IA) and answer practical questions on the final exam. The learning path progresses from planning an experiment through to final evaluation, mirroring the full process of real scientific investigation.

Each sub-topic breaks down a key stage of the practical process, with specific guidance aligned to IB marking criteria. By the end of the unit, you will be able to independently plan and report on a full chemistry investigation.

Core sub-topics in this unit:

Experimental design and procedure

Learn how to write research questions, control variables, and plan safe, valid experimental procedures.

★★⏱ 10 min

Data collection and processing

Master raw data recording, significant figures, uncertainty calculation, and graphical data presentation.

★★★⏱ 12 min

Results analysis and evaluation

Practice analyzing results, identifying error sources, and evaluating experimental validity with targeted improvements.

★★★⏱ 15 min

Collaborative scientific inquiry

Develop skills for planning and contributing to group scientific investigations aligned with IB requirements.

★★⏱ 10 min

2. Common Pitfalls

Wrong move:

Reporting raw data with incorrect significant figures that do not match instrument precision.

Why:

This leads to unnecessary lost marks in both practical exams and internal assessment.

Correct move:

Always match significant figures to the smallest division of the measuring instrument used.

Wrong move:

Using generic error claims like 'human error' in evaluations without specific context.

Why:

IB requires demonstration of critical thinking, so vague claims do not earn evaluation marks.

Correct move:

Identify specific systematic or random errors and explain how they impacted your final result.

Wrong move:

Forgetting to include a full risk assessment when designing your experiment.

Why:

Safety is assessed in practical work, and missing this section can invalidate your investigation.

Correct move:

Always document hazards, risks, and safety mitigations for all procedures and chemicals.

3. Quick Reference Cheatsheet

Concept/Skill	Key Rule/Formula
Absolute uncertainty of a measuring instrument	Half the smallest division of the instrument
Significant figures for processed data	Match to the least precise measurement used in calculation
Percentage uncertainty calculation	$%Δ = \frac{absolute uncertainty}{measured value} \times 100$
Valid experimental design	One independent variable changed, all other variables controlled
Good evaluation requirement	Specific error → impact on result → realistic improvement
IA Criterion Weighting	Planning 20%, Data Collection 30%, Analysis 25%, Evaluation 25%

What's Next

Begin your learning of this unit with the first sub-topic on experimental design, which forms the foundation of all practical chemistry work for IB. Once you complete all four sub-topics here, you will be ready to move on to final exam preparation for your IB Chemistry SL assessment.