DP Chemistry (first assessment 2025)

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Question 23M.2.SL.TZ1.7a

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Date May 2023 Marks available [Maximum mark: 3] Reference code 23M.2.SL.TZ1.7a
Level SL Paper 2 Time zone TZ1
Command term Determine, Predict Question number a Adapted from N/A
a.
[Maximum mark: 3]
23M.2.SL.TZ1.7a
(a)

The following diagram shows a chromatogram.

(a.i)

Determine the identity of the amino acid creating spot C by calculating the Rf value from the chromatogram.


Identity of spot C: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

 

[1]

Markscheme

Identity of spot C:
leucine ✓

(a.ii)

Predict, referring to the structure of the amino acids, whether spot X on the chromatogram in part (a)(i) is more likely to be serine or phenylalanine. Use the table of Rf values and section 33 of the data booklet.

[2]

Markscheme

serine AND more polar «than phenylalanine»
OR
serine AND OH group «on side chain» ✓

hydrogen bonding/greater affinity with stationary phase
OR
less soluble/poor affinity in solvent/mobile phase ✓


M2 may be scored without M1.