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Edexcel Jun 2016 Paper 5 Q22
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![22 Copper and zinc are both in the d-block of the Periodic Table. Copper forms compounds that contain Cu+ and Cu2+ ions but zinc only forms compounds that contain Zn2+ ions. (a) Complete the electronic configurations of the Cu2+ ions and Zn2+ ions and hence explain why copper is classified as a transition metal but zinc is not. (2) Cu2+ [Ar]Zn2+ [Ar](b) Some photochromic glasses contain silver(I) and copper(I) chlorides. Explain, with the aid of an equation, why these photochromic glasses go darker in sunlight. (2)A E R A S I H T N I E T I R W T O N O D A E R A S I H T N I E T I R W T O N O D A E R A S I H T N I E T I R W T O N O D *P46661A02132* 21 Turn over<br />
(c) Copper forms a complex ion with the formula [CuCl4]2. This has the same shape as [Pt(NH3)2Cl2]. Draw the shape of the [CuCl4]2 ion and state the type of bonding between the ligands and the metal ion. Shape Bonding (d) The [CuCl2] ion is formed by boiling a solution of copper(II) chloride with copper turnings and concentrated hydrochloric acid. (i) Write an equation for this reaction. State symbols are not required. (ii) State the meaning of the term disproportionation and explain whether or not this reaction to form the [CuCl2] ion is a disproportionation reaction. (2) (1) (2)22 *P46661A02232* D O N O T W R I T E I N T H I S A R E A D O N O T W R I T E I N T H I S A R E A D O N O T W R I T E I N T H I S A R E A<br />
(iii) Explain why the [CuCl2] ions are colourless. (2)(e) Copper(II) sulfate solution reacts with aqueous sodium hydroxide and with aqueous ammonia. CuSO4(aq) aqueous sodium hydroxide copper(II) hydroxide blue precipitate excess aqueous ammonia deep blue solution containing [Cu(NH3)4(H2O)2]2+ (i) Write the ionic equation for the reaction of copper(II) sulfate solution with aqueous sodium hydroxide. Include state symbols. (ii) State the type of reaction occurring overall when excess aqueous ammonia is added to copper(II) sulfate solution. (1) (1)A E R A S I H T N I E T I R W T O N O D A E R A S I H T N I E T I R W T O N O D A E R A S I H T N I E T I R W T O N O D *P46661A02332* 23 Turn over<br />
(f) 1,2-diaminoethane is a bidentate ligand. It reacts with copper(II) ions in aqueous solution. [Cu(H2O)6]2+ + 3H2NCH2CH2NH2 (cid:85) [Cu(H2NCH2CH2NH2)3]2+ + 6H2O (i) State what is meant by the term bidentate. (1)(ii) Explain, in terms of entropy, why the reaction takes place. (2)(Total for Question 22 = 16 marks) TOTAL FOR SECTION B = 47 MARKS 24 *P46661A02432* D O N O T W R I T E I N T H I S A R E A D O N O T W R I T E I N T H I S A R E A D O N O T W R I T E I N T H I S A R E A<br />](https://learnah.org/wp-content/uploads/2018/08/l_smalljpgJune_2016_QP_-_Unit_5_Edexcel_Chemistry_A-level_22-0.jpg)
![Acceptable Answers Reject Mark (2) d shell sub- shell / orbital other than 3d First mark Electronic configurations: Cu2+ is [Ar] 3d9 and Zn2+ is [Ar] 3d10 IGNORE 4so / full electronic configuration of Ar (1) Second mark If both EC are correct: EITHER Copper (is a transition element because it) forms a (stable) ion with an incompletely / partially filled d-subshell / orbital(s) ALLOW forms an ion with unpaired d electron(s) OR Zinc only forms an ion with a full d-subshell / all d orbitals full (1) If one or both EC are incorrect: Copper (is a transition element because it) forms a (stable) ion with an incompletely filled d-subshell / orbital(s) and zinc only forms an ion with a full d-subshell / all d orbitals full (1) OR OR Acceptable Answers CuCl + AgClCuCl2 + Ag Cu+ + Ag+Cu2+ + Ag CuCl + Ag+Cu2+ + Ag + Cl- ALLOW(1) IGNORE state symbols / half-equations Stand alone mark (Equilibrium moves to the right in sunlight) producing silver (1) IGNORE copper(II) compounds Mark (2) Reject Copper (metal)/ copper(I) compounds Question Number 22(a) Question Number 22(b)<br />
Question Number 22(c) Acceptable Answers Shapesquare planar Reject Mark (2) or ALLOW bonds with or without arrows ALLOW Cls joined by lines in a square ALLOW tetrahedral shape (1) IGNORE brackets and/or charges Bonding - dative (covalent) /co-ordinate ALLOW shown on diagram as arrows from Cl to Cu (1) Rej ect Mark (1) Acceptable Answers Cu + CuCl2 + 2HCl2[CuCl2] + 2H+ OR Cu + Cu2+ + 4Cl2[CuCl2] OR Cu + [Cu(H2O)6]2+ + 4Cl2[CuCl2] + 6H2O OR Cu + [Cu(H2O)6]2+ + 4HCl2[CuCl2] + 6H2O + 4H+ OR Cu + CuCl2 + 2Cl2[CuCl2] IGNORE state symbols, even if incorrect / missing brackets Question Number 22(d)(i)<br />
Acceptable Answers Question Number 22(d)(ii) Disproportionation is the simultaneous oxidation Reject Mark (2) Acceptable Answers Question Number 22(d)(iii) The d-subshell is full / d10 Mark (2) Reject d orbital any number other than 3(d) d-subshell / d orbitals do not split and reduction of a (single) species / atom / element / ion (to form 2 different oxidation states) (1) IGNORE reactant / substance / molecule / compound Not disproportionation because two different species (of copper) are oxidised and reduced OR Not disproportionation as (start with 2 different oxidation states of copper and) only produces 1 oxidation state ALLOW Disproportionation is the other way around / this is reverse disproportionation / comproportionation (1) OR all d orbitals are full ALLOW d shell is full (1) d-d transitions cannot take place OR Electrons cannot move between d orbitals OR Electrons cannot be promoted / excited to higher d orbital(s) (1) IGNORE just movement to different energy level<br />
Acceptable Answers Question Number 22(e)(i) State symbols are required Reject Equations with NaOH / Na+/ SO4 2 ions Mark (1) IGNORE missing square brackets Cu2+(aq) + 2OH(aq)Cu(OH)2(s) OR [Cu(H2O)6]2+(aq) + 2OH(aq)Cu(OH)2(s) + 6H2O(l) OR [Cu(H2O)6]2+(aq) + 2OH(aq)Cu(OH)2(H2O)4(s) + 2H2O(l) OR Cu2+(aq) + 2OH(aq) + 4H2O(l)Cu(OH)2(H2O)4(s) ALLOW equations with [Cu(H2O)4]2+(aq) Question Number 22(e)(ii) Acceptable Answers Reject Ligand exchange / ligand substitution / ligand replacement Acceptable Answers Question Number 22(f)(i) Ligand has 2 atoms that can form Mark (1) Mark (1) Acid/base reaction Deprotonation Reject 2 ligands attached to the ion Ionic bond Just has 2 lone pairs (co-ordinate / dative covalent) bonds (to the metal ion) ALLOW Has 2 lone pairs that form (co-ordinate / dative covalent) bonds ALLOW Has 2 lone pairs that it donates (to the metal ion) ALLOW Forms 2 (co-ordinate / dative covalent) bonds (to the metal ion)<br />
(there are) more particles / moles / species on the right (of the equation) OR (there is an increase from) 4 particles / moles / species on the left of the equation to 7 on the right (1) Second mark (so) Ssystem increases / is positive (and the reaction is thermodynamically feasible) ALLOW Stotal is positive / increasing (and the reaction is thermodynamically feasible) ALLOW (there is) an increase in entropy (and the reaction is thermodynamically feasible) (1) IGNORE Just disorder increases Total for Question 22 = 16 marks Acceptable Answers Question Number 22(f)(ii) First mark Mark (2) Reject Molecules / atoms Incorrect numbers of particles / moles<br />](https://learnah.org/wp-content/uploads/2018/08/June_2016_MS_-_Unit_5_Edexcel_Chemistry_A-level_22-0.jpg)
