Chemistry 9701 · AS & A Level · Chemistry of transition elements

Chemistry of transition elements — practice question

(a)[1]

Define the term transition metal complex

(b)[2]

Platinum can form the compound $[\text{Pt}({\text{NH}}_3)_4\text{Cl}_2][\text{PtCl}_4]$. State the co-ordination numbers and the oxidation numbers of platinum in the two ions in this compound.

(c)[2]

Draw three-dimensional diagrams showing the structures of the two isomers of $[\text{Pt}({\text{NH}}_3)_4\text{Cl}_2]^{2+}$.

(d)[2]

Solutions of the compounds $[\text{Pt}(\text{NH}_3)_4\text{Cl}_2]\text{Br}_2$ and $[\text{Pt}(\text{NH}_3)_4\text{Br}_2]\text{Cl}_2$ can be told apart by a simple chemical test. Complete the table with a test that would positively identify each compound and describe the expected observations for each one.

(e)[3]

In this question, consider geometrical and optical isomerism. What type of isomerism is shown by the following complexes? You should answer geometrical, optical, both or neither. • octahedral $[\text{Co}(\text{NH}_2\text{CH}_2\text{CH}_2\text{NH}_2)_2\text{Cl}_2]^+$ • square planar $[\text{Ni}(\text{CN})_2\text{Cl}_2]^{2-}$ • tetrahedral $[\text{CuBr}_2\text{Cl}_2]^{2-}$

(f)[3]

Many enzymes contain transition metal complexes. Describe, with the help of a suitably labelled diagram, how an enzyme catalyses the breakdown of a substrate molecule.

Worked solution & mark scheme

This 13-mark question has a full step-by-step worked solution and mark scheme. One marking point: A central metal atom/ion with one or more ligands arranged around it.

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