CAIE A Level Chemistry 9701 · Chemistry of transition elements
A student adds an excess of concentrated ammonia solution to an aqueous solution containing the hexaaquacopper(II) ion, . A pale blue precipitate forms first and then dissolves to give a deep blue solution.
Suggest why the deep blue solution has a different colour from the original aqueous solution. In your answer, refer to the d orbitals and the effect of the change of ligand on the splitting energy, .
5 marks, so the mark scheme is looking for about 5 separate creditworthy points. Making the same point twice in different words earns it once.
Suggest means: Apply what you know to an unfamiliar situation. There may be more than one acceptable answer. Reason from the principle you have learned to the new context, and say which principle you are using.
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