Good chemistry is not just about knowing what reactions to perform, but how to perform them reliably, safely and with meaningful results. Chapter 12 is about the practical side of chemistry, covering the experimental techniques and analytical methods that underpin everything else in the course.

We begin with experimental design, looking at the apparatus used to measure time, temperature, mass and volume, and introducing key terminology around solutions, including solute, solvent, saturated solution and filtrate. We then cover acid-base titrations in detail, examining how a burette, volumetric pipette and indicator are used together to determine the concentration of an unknown solution with precision.

From there, we move into separation and purification techniques, including filtration, crystallisation, simple and fractional distillation, and the use of suitable solvents. We look at how melting points and boiling points can be used to identify substances and assess their purity. The chapter also covers chromatography, both for coloured and colourless substances, and introduces the Rf value as a way of characterising and identifying components in a mixture.

The chapter closes with qualitative chemical analysis, where we develop a systematic toolkit for identifying unknown ions and gases. This includes flame tests for metal cations, precipitation reactions using sodium hydroxide and ammonia to identify aqueous cations, and a range of tests for anions and gases. Taken together, these techniques give you the means to identify an unknown substance from first principles, which is one of the most satisfying things you can do in a chemistry laboratory.