A2 CHEMISTRY
CHROMATOGRAPHY WORKSHEET
1
Explain, giving diagrams, the difference between separation by partition and
separation by adsorption.
2
Amino acids may be separated by using two-dimensional paper chromatography.
This involves putting a spot of the mixture on the corner of a piece of
chromatography paper and allowing a solvent to soak up the paper. The paper is
then dried, turned through 90°and placed in a second solvent. This method gives
better separation than a one solvent method.
(i)
Paper chromatography relies on partition between the solvent applied
and another phase. What is this second phase composed of?
……………………………………….
3
Write a sentence to explain the difference between paper chromatography and
thin layer chromatography.
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4
In gas/liquid chromatography the mobile phase is a …………..
(e.g. …………………..) and the stationary phase is a non-volatile ……………….
coated on to small inert particles.
The graph below shows a GLC chromatogram of a mixture of organic chemicals.
Pentan-2-one
Hex-1-ene
0
heptane
propanone
ethanal
ethoxyethane
Recorder
response
5
15
10
Time/min
Time of injection
(i)
Which compound is present in the largest amount?
……………………….
(ii)
Which compound has a retention time of 2 mins?
………………………
(iii)
What further method must be used to help identify unknown compounds after
they have passed through a GLC column?
5
……………………………..
Give 3 differences between gas/liquid chromatography and high performance
liquid chromatography.
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6
(i)
Give one example each of an analytical use of
high performance liquid chromatography
…………………………………………………………………………………………..
(ii)
gas/liquid chromatography
………………………………………………………………………………………….