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CAIE A-Level Chemistry A2 28.4.2 The Overall Polarity of Complexes Such Questions

Practise deducing whether complex stereoisomers are polar by testing the cancellation of bond dipoles in 3D.

Syllabus
2028–2030
Course
Chemistry 9701
Level
A2

Exam points

  • use the complete three-dimensional structure rather than the complex charge alone to assess polarity
  • identify a symmetric trans arrangement as non-polar when equal opposing bond dipoles cancel
  • identify a cis arrangement as polar when its polar bonds are arranged so their dipoles do not cancel

CAIE A-Level Chemistry A2 28.4.2 The Overall Polarity of Complexes Such Questions question 1

[Maximum number: 1]

An aqueous solution of copper(II) sulfate is a blue colour due to the presence of [Cu(H2O)6]2+\left[\mathrm{Cu}\left(\mathrm{H}_{2} \mathrm{O}\right)_{6}\right]^{2+} complex ions.

If an excess of ammonia is added to a solution of [Cu(H2O)6]2+\left[\mathrm{Cu}\left(\mathrm{H}_{2} \mathrm{O}\right)_{6}\right]^{2+} a deep blue solution containing [Cu(NH3)4(H2O)2]2+\left[\mathrm{Cu}\left(\mathrm{NH}_{3}\right)_{4}\left(\mathrm{H}_{2} \mathrm{O}\right)_{2}\right]^{2+} complex ions is formed.

Use your answer in (b)(i) to deduce whether each of these isomers is polar or non-polar. polarity of isomer 1
polarity of isomer 2

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