DP Chemistry (last assessment 2024)

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Question 18M.3.hl.TZ1.16e

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Date May 2018 Marks available [Maximum mark: 3] Reference code 18M.3.hl.TZ1.16e
Level hl Paper 3 Time zone TZ1
Command term Explain Question number e Adapted from N/A
e.
[Maximum mark: 3]
18M.3.hl.TZ1.16e

Many drugs, including aspirin, penicillin, codeine and taxol, have been modified from compounds that occur naturally.

(e)

Many drugs are chiral. Explain how a polarimeter can be used to determine the relative proportion of two enantiomers.

[3]

Markscheme

«pure» enantiomers rotate the plane «of plane-»polarized light «by equal angles» in opposite directions

 

Any two of:

find angle of rotation of pure enantiomers

measure angle of rotation of mixture

mixture has angle between that of two enantiomers

ratio of angles gives purity

 

[3 marks]

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