How can you separate a pure substance from a mixture?

To separate a pure substance from a mixture, you must use physical separation methods that exploit differences in physical properties—such as boiling point, particle size, solubility, or magnetism. These methods do not change the chemical identity of substances. Common techniques include:

1. Filtration: Used to separate solids from liquids or gases. For example, sand can be separated from water using a filter paper.
2. Distillation: Used when components have different boiling points. For instance, salt water can be distilled to recover pure water by evaporating and condensing the vapor.
3. Evaporation: If you need the solid component, you can evaporate the liquid—like getting salt crystals from salt water.
4. Magnetic Separation: Magnetic materials like iron filings can be separated from non-magnetic ones like sulfur.
5. Chromatography: This method separates dissolved substances based on how they travel through a medium (used for inks, dyes, and plant pigments).

Each method relies on a physical difference between substances in the mixture. Importantly, these techniques don’t create or destroy substances—they simply isolate pure components from mixtures. Once separated, the pure substance will exhibit fixed physical and chemical properties unique to itself.