Chromatography for AQA A-level 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

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