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CAIE A-Level Chemistry 28.2.7 Ligand Exchange Reactions

Practise equations and observations when water ligands in Cu(II) or Co(II) complexes are replaced by ammonia or chloride.

Syllabus
2028–2030
Course
Chemistry 9701
Level
A2

Exam points

  • name ligand exchange only when one ligand replaces another without changing the metal oxidation state
  • balance complex charge, ligand and water terms in equations such as aqueous Cu2+ with excess ammonia
  • distinguish ligand exchange in excess reagent from the initial hydroxide precipitation caused by limited ammonia

28.2.7—Ligand exchange reactions question 1

[Maximum number: 1]

Copper is a transition element and has atomic number 29.

The following equilibrium exists between two complex ions of copper in the +2 oxidation state.

[Cu(H2O)6]2++4Cl−⇌[CuCl4]2−+6H2O\left[\mathrm{Cu}\left(\mathrm{H}_{2} \mathrm{O}\right)_{6}\right]^{2+}+4 \mathrm{Cl}^{-} \rightleftharpoons\left[\mathrm{CuCl}_{4}\right]^{2-}+6 \mathrm{H}_{2} \mathrm{O}

Name the type of reaction occurring here.

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