Extraction: definition in chemistry
Extraction: Separating a substance from a mixture, often by dissolving it selectively in a solvent. The word is also used for obtaining a metal from its ore.
Extraction works because a substance dissolves better in some solvents than in others. In liquid–liquid extraction, two liquids that do not mix, such as water and hexane, are shaken together so the target compound moves into the layer where it is more soluble. Metal extraction uses chemical reactions instead, for example removing the oxygen from iron oxide in a blast furnace.
Examples
- Brewing tea — hot water extracts flavor and caffeine from the leaves
- Decaffeinating coffee beans with supercritical carbon dioxide
- Shaking iodine solution with hexane moves the iodine into the hexane layer
- Extracting iron from its ore in a blast furnace
On the periodic table
How a metal is extracted depends on its reactivity: very reactive metals such as sodium and aluminum are extracted by electrolysis, while less reactive ones such as iron are reduced with carbon.