An aqueous solution of iron(III) ions reacts with ethanedioate ions according to the following equation:
[Fe(H2O)6]3+(aq)+3C2O42−(aq)→[Fe(C2O4)3]3−(aq)+6H2O(l) \text{[Fe(H}_2\text{O)}_6\text{]}^{3+}(\text{aq}) + 3\text{C}_2\text{O}_4^{2-}(\text{aq}) \rightarrow \text{[Fe(C}_2\text{O}_4)_3\text{]}^{3-}(\text{aq}) + 6\text{H}_2\text{O}(\text{l}) [Fe(H2O)6]3+(aq)+3C2O42−(aq)→[Fe(C2O4)3]3−(aq)+6H2O(l)Which statement about this reaction is correct?
The coordination number of the iron ion decreases from 6 to 3.
The enthalpy change (ΔHθ\Delta H^\thetaΔHθ) is highly negative because iron–oxygen bonds are replaced by stronger iron–nitrogen bonds.
The entropy change (ΔSθ\Delta S^\thetaΔSθ) is large and positive because the reaction results in an increase in the number of particles in solution.
The shape of the iron complex changes from octahedral to tetrahedral.
63 exam-style questions on AQA A Level Chemistry Transition metals (A-level only), covering General properties of transition metals (A-level only), Substitution reactions (A-level only), Shapes of complex ions (A-level only), Formation of coloured ions (A-level only), Variable oxidation states (A-level only), and Catalysts (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.