Flashcards
Chromatography
Flashcards do conjunto (7)
- 1Describe paper chromatographyA drop of ink is placed on a piece of filter paper. A few drops of water is then added to the ink, the colour spreads out from the ink drop and separates into several different colours.
- 2In what circumstances would the colour separate?1. The pigments have different solubilities in the solvent
2. The pigments have different degrees of attraction for the filter paper - 3What other solvents can be used instead of water?Ethanol and propanone
- 4What are factors that affect speed and distance of chromatography?-Solubility in the solvent and degrees of attraction for the filter paper affect the speed
-The type of solvent used can affect the distance travelled - 5What are uses of chromatography?1. Identifying substances in a mixture
2. Separating out substances in a mixture and thereby purifying them
3. Identify colourless substances - 6How are colourless substances identified by chromatography?Spray the filter paper with a locating agent, which reacts with the colourless spot and forms a coloured compound. This colour is usually further developed by warming the paper in an oven. Substances are then identified by the distances they've travelled from the base line compared with the solvent front.
- 7How is the Rf value calculated?Rf value= distance from the base line to the centre of the spot/ distance of the solvent front from the base line
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- IGCSE Chemistry (C2) FlashCards sobre Chromatography, criado por Maxine Gill em 23-05-2016.
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- Maxine Gill
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