CHEMISTRY Unit 1.2/1.6 (AQA - mixtures and separation)

Mixture

Two or more elements or compounds not chemically combined together, where the chemical properties of each substance are unchanged.

Chemical properties of substances in a mixture

They are unchanged

Methods used to separate mixtures

Physical processes such as filtration, crystallisation, simple distillation, fractional distillation, and chromatography.

Role of physical separation processes in chemical reactions

They do not involve chemical reactions and no new substances are made.

Filtration

A physical process used to separate an insoluble solid from a liquid.

Crystallisation

A physical process used to separate a soluble solid from a solution by evaporating the solvent to leave crystals.

Simple distillation

A physical process used to separate a solvent from a solution based on differences in their boiling points.

Fractional distillation

A physical process used to separate mixtures of liquids with different boiling points.

Chromatography

A physical process used to separate mixtures of soluble substances based on their different solubilities in a solvent.