BRAINCAKEChromatography
Chromatography separates the components of a mixture so they can be identified. All forms of chromatography have two phases:
• a stationary phase, which does not move, e.g. a solid such as silica on a plate, or a liquid held on a solid support
• a mobile phase, which moves through or over the stationary phase, e.g. a liquid solvent or a gas
Components separate because each one interacts with the two phases to a different extent. A component that is held strongly by the stationary phase moves slowly; a component that spends more time in the mobile phase moves quickly. After a time, the components are at different positions (or leave at different times).
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Key terms in this lesson
- thin-layer chromatography
- A chromatography technique that separates components of a mixture by adsorption onto a thin layer of solid, such as silica, on a plate.
- gas chromatography
- A chromatography technique that separates volatile components of a mixture by their differing solubilities in a liquid stationary phase, carried by a gas.
More in Chromatography and Qualitative Analysis
- Thin-Layer Chromatography
- Rf Values
- Gas Chromatography
- Retention Times and Peak Areas
- Qualitative Tests for Alkenes
- Qualitative Tests for Haloalkanes
- Qualitative Tests for Phenols
- Qualitative Tests for Carbonyls
All 10 lessons in Chromatography and Qualitative Analysis · All OCR A-level Organic Chemistry topics