Chromatography

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  • Created by: joshd
  • Created on: 01-04-14 17:42
What can you use paper chromatography to do?
To identify different substances in a mixture. It uses the fact that different substances wash through wet filter paper at different rates.
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What do you do to do paper chromatography? (1)
1)Put spots of each mixture being tested on a pencil baseline on filter paper.2)Roll up the paper and put it in a beaker containing a solvent, such as ethanol or water. The baseline must be kept above the level of the solvent.
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What do you do to do paper chromatography? (2)
3)The solvent seeps up the paper, taking the samples with it.4)The different chemicals in the sample form separate spots on the paper.
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What do you do to do paper chromatography? (3)
5)The result of chromatography analysis is called a chromatogram. A chromatogram with four spots means there are at least four different substances in the sample mixture.
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What is a use for chromatography?
To separate out the mixture of colouring agents in food.
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How do you identify which agents are present?
To identify which agents are present,run samples of known mixtures alongside the unknown mixture and compare where the spots end up.
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What is the Rf value?
The Rf value is the ratio between the distance travelled by the dissolved substance and the distance travelled by the solvent.
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What is the formula for Rf value?
distance travelled by substance/ distance travelled by solvent
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What are Rf values used in?
Rf values are used in the food industry and in forensic science. Scientists keep tables of these values and refer to them to identify substances like food additives and drugs.
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Card 2

Front

What do you do to do paper chromatography? (1)

Back

1)Put spots of each mixture being tested on a pencil baseline on filter paper.2)Roll up the paper and put it in a beaker containing a solvent, such as ethanol or water. The baseline must be kept above the level of the solvent.

Card 3

Front

What do you do to do paper chromatography? (2)

Back

Preview of the front of card 3

Card 4

Front

What do you do to do paper chromatography? (3)

Back

Preview of the front of card 4

Card 5

Front

What is a use for chromatography?

Back

Preview of the front of card 5
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