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Chromatography for Edexcel GCSE Chemistry

Chromatography

This page covers the following topics:

1. Formulations
2. Chromatography
3. Rf values

Formulations are complex mixtures of chemicals which have a specific use.

Formulations

Chromatography can be used to identify the substances present in a mixture of solutes.

Chromatography

Chromatograms can be identified by calculating the Rf values for the separated components of mixtures.

Rf values

1

Calculate the Rf value for the blue ink in the chromatogram shown.

0.425

Calculate the Rf value for the blue ink in the chromatogram shown.

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.

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?

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

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?

4

Calculate the Rf value for the purple ink in the chromatogram shown.

0.75

Calculate the Rf value for the purple ink in the chromatogram shown.

5

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

Cough syrup.

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

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