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CAIE A-Level Chemistry 29.4.3 Effect on Plane-Polarised Light

Practise comparing the effects of two pure enantiomers at the same concentration on plane-polarised light.

Syllabus
2028–2030
Course
Chemistry 9701
Level
A2

Exam points

  • state that each pure enantiomer rotates the plane of plane-polarised light and is optically active
  • at equal concentration, give equal rotation angles for the two enantiomers under matching conditions
  • state that the rotations are in opposite clockwise and anticlockwise directions

29.4.3—Effect on plane polarised light of the two question 1

[Maximum number: 1]

The amino acid serine, HOCH2CH(NH2)COOH\mathrm{HOCH}_{2} \mathrm{CH}\left(\mathrm{NH}_{2}\right) \mathrm{COOH}, exists in two optically active forms. These optical isomers, isomer P and isomer Q, are shown in Fig. 8.1.

Fig. 8.1

Fig. 8.1

A solution of pure isomer P of a particular concentration rotates plane polarised light by 5.0∘5.0^{\circ} in a clockwise direction.

Describe how a solution of pure isomer Q of the same concentration affects plane polarised light.

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