Worksheet
Lesson: Chromatography
1.
The diagrams show the results of paper chromatography of four separate amino acids in two
different solvents.
Run in Solvent A
Run in Solvent B
(a)
Calculate the Rf value for amino acid B in:
(i) Solvent A
(ii) Solvent B
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(b)
2.
Explain the difference in Rf value.
a) In an experiment a mixture of amino acids was separated using paper chromatography and
a solvent (Y). The resulting paper is shown below. Use the table of Rf values below to decide
which of the labelled spots, P, Q or R is arginine.
Run in Solvent Y
b) In a separate experiment a mixture of alanine, arginine and tyrosine was applied and
solvent X moved 20 cm up the paper. How far up the paper from the origin would
Tyrosine be located?
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3.
What is the correct order of the following steps to describe the process of 2-way chromatography?
a)
b)
c)
d)
e)
f)
g)
h)
4.
Calculate Rf values.
Run the chromatogram in the 1st solvent
Measure the distance the spots and solvent have moved
Apply mixture to the chromatography paper
Spray with locating agent
Run the chromatogram in the 2nd solvent
Rotate the paper
Mark the paper
The diagram shows the result of a two-way chromatogram.
a) Which letters correspond to amino acids that are equally soluble in the first solvent that was
used?
b) Explain how you can tell that Q and R are not the same amino acid.
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