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Chromatography
AQA A Level Chemistry
Question | Answer |
---|---|
Describe CC. | A column is packed with a solid (silica) and a solvent moves down the column |
Describe GC. | A column is packed with a solid or with a solid coated by a liquid, and an inert gas is passed through the column under pressure at high temperature |
Describe TLC. | A plate is coated with a solid (silica on a plastic plate) and a solvent moves up the plate |
In GC, what is the retention time? | The time taken for the substances to be eluted |
What are the general names given to the phases in chromatography? | Stationary and mobile |
What does CC stand for? | Column Chromatography |
What does GC stand for? | Gas Chromatography |
What does TLC stand for? | Thin Layer Chromatography |
What is chromatography? | A process to separate the constituents of a mixture (usually coloured dyes at iGCSE) - separation depends on the balance between solubility in the mobile phase and the retention by the stationary phase |
What is the Rf value and how is it calculated? | Retention factor = (distance moved by the component of a solute)/(distance moved by the solvent) |