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Chromatography for SQA National 5 Chemistry







This page covers the following topics:
1. Formulations
2. Chromatography
3. Rf values
Formulations are complex mixtures of chemicals which have a specific use.
Chromatography can be used to identify the substances present in a mixture of solutes.
Chromatograms can be identified by calculating the Rf values for the separated components of mixtures.
1
Calculate the Rf value for the blue ink in the chromatogram shown.
0.425

2
In a paper chromatography experiment, the yellow coloured ink is found to not move up the paper. What is the retention factor? Why does the ink not move?
0 - the yellow ink is not soluble in the solvent used.
3
In a paper chromatogram, the solvent travels 7.2 cm up the paper. The Rf value for red ink is 0.5. How far did the red ink travel up the paper?
3.6 cm
4
Calculate the Rf value for the purple ink in the chromatogram shown.
0.75

5
Which is an example of a formulation: a block of pure iron, cough syrup, oxygen gas.
Cough syrup.
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