Topic questions Atomic structure and the periodic table Metal-aqua ions in solution
6 questions · 78 marks · about 1.5 hours
Chromium forms the complex ions [Cr(NH3)6]3+ and [Cr(OH)6]3–.
Which statement(s) about the complexes is / are correct?
1 Chromium is in the same oxidation state in each complex ion.
2 The complex ions are different colours.
3 The complex ions have different coordination numbers.
A 1, 2 and 3
B Only 1 and 2
C Only 2 and 3
D Only 1
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 the d-block elements in Period 4 of the periodic table (Sc to Zn).
* Explain, with examples from Period 4, what is meant by the terms d-block element and transition element.
Explain why some d-block elements are not transition elements.
Use electron configurations to support your explanations.
Describe precipitation reactions using either copper or chromium ions as examples.
Include equations.
Describe ligand substitution reactions using either copper or chromium ions as examples.
Include equations.
The ethanedioate ion, C2O42–, is a bidentate ligand.
A complex ion of cobalt(III) contains two ethanedioate ligands and two water ligands.
Determine the charge of this complex ion and the coordination number of cobalt in the complex ion.
Charge of complex ion........
Coordination number of cobalt........
An acidified solution containing Cr2O72– ions reacts with vanadium(III) ions in a redox reaction to form a solution containing Cr3+ ions and VO2+ ions.
Construct the overall equation for this reaction.
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 reactions of ions and compounds of transition elements.
A student carries out two experiments on a solution containing [Cr(H2O)6]3+(aq).
Experiment 1 The student adds an excess of aqueous ammonia to a solution containing [Cr(H2O)6]3+ until a purple solution is formed.
Experiment 2 The student carries out the following reaction sequence.
Step 1 NaOH(aq) is added slowly to a solution containing [Cr(H2O)6]3+(aq) in a boiling tube. A grey–green precipitate forms.
Step 2 An excess of NaOH(aq) is added to the boiling tube. The precipitate dissolves and a green solution forms containing a 6 coordinate complex ion.
Step 3 H2O2 is added to the mixture and the boiling tube is heated. A yellow solution forms.
Step 4 The solution in the boiling tube is acidified. The solution now contains Cr2O72−(aq).
What is the formula of the complex ion in the purple solution that forms in Experiment 1
Suggest an equation for the reaction in Experiment 2, Step 1. Include state symbols.
Draw a 3-D diagram for the shape of the complex ion that forms in Experiment 2, Step 2 Include the charge of the ion.
What is the formula of the ion that causes the yellow colour in Experiment 2, Step 3
State the colour of the solution that forms in Experiment 2, Step 4.
Vanadium ions have four common oxidation states. Table 18.1 shows the colours of the ions in aqueous solution.
Complete the electron configuration of a V3+ ion.
The student adds excess iron to a solution containing VO2+(aq) ions, and observes that the colour of the solution changes from blue to green and then to violet.
Use the relevant standard electrode potentials shown in Table 18.2 to explain these observations.
Construct an equation for the first colour change from blue to green.
Iron(II) gluconate, C12H22FeO14, is the active ingredient in some brands of iron supplements.
A student carries out an experiment to determine the mass of iron(II) gluconate in one tablet of an iron supplement, using the method below.
Stage 1 The student crushes two tablets and dissolves the powdered tablets in dilute sulfuric acid.
Stage 2 The student makes up the solution from Stage 1 to 250.0 cm3 in a volumetric flask.
Stage 3 The student then titrates 25.0 cm3 portions of the solution obtained in Stage 2 with 0.00200 mol dm−3 potassium manganate(VII).
The student obtains a mean titre of 13.50 cm3.
In this titration, 1 mol of manganate(VII) ions reacts with 5 mol of iron(II) ions.
Explain why the student used 0.00200 mol dm−3 potassium manganate(VII) solution for this titration, rather than the more usual concentration of 0.0200 mol dm−3 used in manganate(VII) titrations.
Use the student’s results to determine the mass, in mg, of iron(II) gluconate in one tablet.
Give your answer to 3 significant figures.
Also involves Thermal decomposition
This question is about reactions of iron compounds.
In the boxes, write the formulae of A and B.
The student thinks that the reaction of iron(II) sulfide with H+ / H2O is a redox reaction.
Explain, with reasons, whether the student is correct.
Write the equation for the reaction of [Fe(H2O)6]2+(aq) with Cl2(g).
Construct an equation for the reaction of H2S(g) with H+(aq)/MnO4−(aq).
Memes
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