Mixture

Summary: Two or more substances (elements or compounds) mixed together but not chemically combined. Can be separated by physical means. Tags: igcse chemistry definition atomic-structure Created: 2026-07-14 Last Updated: 2026-07-14

A mixture is a physical combination of two or more substances (elements or compounds) that are not chemically bonded to one another, meaning no new chemical substance is formed and the process can be reversed by physical means. Unlike pure compounds, mixtures have no fixed composition and their components retain their individual chemical properties — for example, iron filings in a sand-iron mixture remain magnetic and will still react with dilute acid. Separation techniques exploit differences in the physical properties of the components: filtration separates insoluble solids from liquids, simple distillation separates a solvent from dissolved solids, fractional distillation separates miscible liquids with different boiling points, and chromatography separates dissolved substances based on their differing solubility in a solvent. The concept of a mixture underpins much of IGCSE experimental chemistry, and students should be able to identify the most appropriate separation method when given a scenario. A common exam distinction is that the melting point of a pure substance is sharp and fixed, whereas a mixture melts over a range of temperatures — a practical test for purity.

Key term — IGCSE Chemistry (0620/0971) glossary.