9 Worksheet 3
Paper and thin-layer chromatography
1
a
The table below shows the distances moved by the solvent and three substances undergoing
paper chromatography. Distances are given to the nearest mm.
Substance
Distance moved (cm)
solvent
10.0
A
4.0
B
5.0
C
6.0
Calculate the Rf values for the three substances.
b The following chromatogram was obtained when using the same solvent and a mixture
containing two of the substances.
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i Using measurements from the diagram, calculate the Rf value for each spot.
ii Which of the substances – A, B or C – are spot I and spot II?
c Why should the same solvent be used for both experiments?
d Use the diagram below to help explain the process of two-dimensional paper
chromatography.
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COAS Chemistry 2 Teacher Resources
Original material © Cambridge University Press 2005, 2007, 2009
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9 Worksheet 3
2
Thin-layer chromatography is used to separate substances and is an alternative to paper
chromatography.
a Name two substances that can be used as the stationary phase in thin-layer
chromatography.
b i Explain why dry thin-layer plates operate through adsorption.
ii Explain why, if the same plates are only partially dried, the system operates through
partition and adsorption.
c Give three advantages of thin-layer chromatography over paper chromatography.
Total:
COAS Chemistry 2 Teacher Resources
22
Score:
Original material © Cambridge University Press 2005, 2007, 2009
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