EduNinja• Interpret simple chromatograms to identify: (a) unknown substances by comparison with known substances (b) pure and impure substances
A chromatography experiment is carried out to analyse the pigments present in four different types of leaf. The student carrying out the experiment forgot to complete his table of results, which is shown.
Which row identifies the values of F, G and H ?
F
G
H
2
3.2
0.80
3
3.5
0.83
2
3.2
0.86
3
3.5
0.78
The chromatogram obtained using four substances, J, K, L and M, is shown.
Which statement about M is correct?
It is a mixture of J and K only.
It is a pure substance.
It is a mixture of J, K and L.
It is a mixture of J, K and an unknown substance.
Paper chromatography is used to separate four different coloured inks, W, X, Y and Z, and an unknown ink T.
The chromatogram is shown.
Which inks are present in ink T?
W and X
W and Y
X and Z
Y and Z
Chromatography can be used to test the purity of substances.
The diagram shows the chromatogram of a coloured substance.
How does this chromatogram show that this substance is not pure?
Substance Q is tested using paper chromatography.
The resulting chromatogram is shown.
Which statement is correct?
A Q is a pure substance.
B The value of the lower spot is 0.25.
C Q is a mixture of at least two different substances.
D Q is a compound of two elements.
Proteins are a major constituent of food.
Proteins are polymers.
A colourless mixture of amino acids was separated by chromatography.
Amino acid X has an value of 0.8.
The chromatogram of the mixture after treatment with a locating agent is shown.
On the diagram put a ring around the spot caused by amino acid X.
Alcohols are a 'family' of organic molecules which have the same general formula.
Chromatography can be used to identify simple sugars in a mixture.
A student analysed a mixture of simple sugars by chromatography. All the simple sugars in the mixture were colourless.
How could a student identify a simple sugar from its value?
Sometimes not all the substances in a mixture can be identified from the chromatogram produced.
Explain why this may happen.
Molecules A and B can form condensation polymers.
A
Molecule A is a simple sugar unit which can be made by hydrolysis of complex carbohydrates.
Name the technique used to identify the individual sugar units made by the hydrolysis of a complex carbohydrate.