CAIE A Level Chemistry 9701 · Chemistry of transition elements
In an aqueous solution containing an excess of ethanedioate ions, ions react to form a complex ion in which each iron(III) ion is surrounded by three ethanedioate ligands. The ethanedioate ion, , is a bidentate ligand.
Describe the formula, charge, geometry (shape and bond angles) and coordination number of the complex ion formed, and explain why the ethanedioate ion can act as a bidentate ligand.
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.
Describe means: Say what happens or what something is like, in order and with detail. You are not being asked why. If there is data, quote it: name the trend, then give figures with units at the points where it changes.
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