Dative covalent bonds

This question is about reactions of compounds of iron and copper.

Complete the electron configuration of

an Fe atom: 1s²........

a Cu²⁺ ion: 1s²........

Solutions of iron(II) sulfate, FeSO₄, and copper(II) sulfate, CuSO₄, can be distinguished by adding aqueous sodium hydroxide.

Describe what would be observed when NaOH(aq) is added to each solution.

Observation with FeSO₄(aq)........

Observation with CuSO₄(aq)........

The cyclic organic compound pyridine, C₅H₅N, can act as a monodentate ligand.

The structure of pyridine is shown below.

What is meant by a monodentate ligand ?

Aqueous copper(II) sulfate reacts with salicylic acid to form a complex ion which has two stereoisomers.

One isomer of the complex ion is shown:

Draw the other stereoisomer of the complex.

Identify the type of stereoisomerism shown by the complexes.

Type of stereoisomerism........

Calculate the percentage by mass of CuSO₄•5H₂O in Mixture A.

Give your answer to 3 significant figures.

Percentage of CuSO₄•5H₂O in Mixture A =........ %

The student repeats their method, but after carrying out Step 1 they leave the solution exposed to the air for a few days. Some of the iron(II) sulfate is oxidised to iron(III) sulfate.

The student then continues with Step 2, Step 3 and Step 4 of the method.

This mean titre is greater than 31.15 cm³.

Suggest why this mean titre is greater than 31.15 cm³.

This question is about compounds and ions of iron(II) and iron(III) that contain ethanedioate ions, C₂O₄^2–.

The C₂O₄^2– ion, shown below, is an example of a bidentate ligand.

Explain what is meant by the term bidentate ligand.

A complex ion E contains three C₂O₄^2– ions bonded to an iron(III) ion in an octahedral shape.

Complex ion E exists as a mixture of two optical isomers.

Draw 3D diagrams to show the structures of the optical isomers of E.

Include any overall charge.

A student plans an investigation to find the number of waters of crystallisation, x, in a sample of hydrated iron(II) ethanedioate, FeC₂O₄•xH₂O.

The student decides to carry out a redox titration between solutions of iron(II) ethanedioate and potassium manganate(VII) in acidic conditions.

In the titration, both iron(II) ions and ethanedioate, C₂O₄^2–, ions are oxidised.

Construct half-equations for the oxidation of iron(II) and ethanedioate ions.

Oxidation of iron(II) ions

Oxidation of ethanedioate ions

The uncertainty in each burette reading is ±0.05 cm³.

Calculate the percentage uncertainty for the titre in Titration 1.

* In the titration, 5 mol of iron(II) ethanedioate reacts with 3 mol of manganate(VII) ions.

Analyse the student’s results to find the number of waters of crystallisation, x, in the hydrated

iron(II) ethanedioate, FeC₂O₄•xH₂O.

This question is about reactions of transition metal compounds.

Explain why ethane-1,2-diamine can act as a bidentate ligand.

The iron(III) ion, Fe³⁺, forms a complex ion A with two ethane-1,2-diamine ligands and two chloride ligands.

Complex ion A has cis and trans stereoisomers. One of these stereoisomers exists as optical isomers.

Determine the empirical formula, with charge, of complex ion A and draw the 3-D structures of the three stereoisomers.

Empirical formula with charge........

Structures

Aqueous sodium hydroxide is added to an aqueous solution of iron(II) sulfate. A pale green precipitate forms which turns brown when left to stand in air.

Write an ionic equation for the formation of the pale green precipitate.

* This question is about copper and copper compounds.

Experiment 1 Hydrochloric acid, HCl (aq), is added to an aqueous solution containing [Cu(H₂O)₆]²⁺ complex ions. A yellow-green solution forms containing complex ion B.

Experiment 2 A piece of copper metal is heated with concentrated sulfuric acid. A reaction takes place forming a pale blue solution C and 45 cm³ of a gas D, measured at RTP. The mass of gas D is 0.12 g.

Experiment 3 An excess of copper(II) oxide is heated with dilute nitric acid. The resulting mixture is filtered. The filtrate is a blue solution E. Aqueous potassium iodide, K I (aq), is added to the blue solution E. A white precipitate F and a brown solution G form.

Determine the formulae of B – G. Construct equations for the reactions taking place, include any changes in oxidation number,

and show your working where appropriate.

This question is about d-block elements.

Most d-block elements are also classified as transition elements.

Explain why scandium and zinc are classified as d-block elements but are not also transition elements.

Your explanations should include full electron configurations.

What is meant by a bidentate ligand ?

* Determine the formulae of A and B. Write the ionic equation for the ligand substitution and show 3D structures for the three stereoisomers of B.