Chapter summary

The whole chapter in two lists and a glossary.

Matter divides into pure substances and mixtures, and in the natural world pure substances are scarce while mixtures are everywhere.
A mixture is matter in which two or more components are mixed without being chemically changed. Their physical and chemical properties survive unaltered inside it, and physical methods can separate them again.
A mixture with one composition throughout is homogeneous; one whose composition is not uniform is heterogeneous.
A homogeneous mixture is also called a solution, and in any small part of it the concentration, colour, density and transparency are the same.
The component present in the larger amount is the solvent and the rest are solutes.
Whether a solute dissolves in a solvent is decided by the temperature and by the polar nature of the solvent and the solute.
The water solubility of a gas changes with the pressure of that gas above the water and with the temperature — and for a gas, unlike most solids, heating makes less of it dissolve.
Composition can be given as a mass fraction (m/m), a volume fraction (v/v), a mole fraction, a mass-volume ratio (m/v) or a mole-volume ratio (n/v). The last of these is called the concentration and its unit is mol dm^-3.

And the separation techniques

In panning rice, floating bad eggs and winnowing, components are separated mechanically using the density of the components. Sieving and filtering use the size of the particles.
Evaporation can separate components because their boiling points differ from one another.
Crystallisation and recrystallisation use the concentration of a solution, raising it until the saturation concentration is passed.
Solvent extraction moves a solute that is only slightly dissolved in one solvent into a second solvent in which it has a higher solubility. The two solvents must not mix.
Distillation heats a mixture and collects, by cooling, the components that vaporise at the temperature matching each one's boiling point. There are three kinds — simple, fractional and steam — differing in the technique used and in the characteristics of the components.
Chromatography passes a flow of volatile solvent through a mixture placed on a special paper. Components separate because they travel through the paper at different speeds, according to how strongly each is attracted to the cellulose.