Cambridge A Level Chemistry 9701 — 2010 Oct/Nov Paper 3 · Variant 1

This document consists of 11 printed pages and 1 blank page. DC (CW/SW) 28271/4 © UCLES 2010 [Turn over UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS General Certificate of Education Advanced Subsidiary Level and Advanced Level READ THESE INSTRUCTIONS FIRST Write your Centre number, candidate number and name on all the work you hand in. Give details of the practical session and laboratory where appropriate, in the boxes provided. Write in dark blue or black pen. You may use a soft pencil for any diagrams, graphs or rough working. Do not use staples, paper clips, highlighters, glue or correction fluid. DO NOT WRITE IN ANY BARCODES. Answer all questions. You may lose marks if you do not show your working or if you do not use appropriate units. Use of a Data Booklet is unnecessary. Qualitative Analysis Notes are printed on pages 11 and 12. At the end of the examination, fasten all your work securely together. The number of marks is given in brackets [ ] at the end of each question or part question. * 3 9 3 3 2 7 9 2 9 0 * CHEMISTRY 9701/31 Advanced Practical Skills October/November 2010 2 hours Candidates answer on the Question Paper. Additional Materials: As listed in the Instructions to Supervisors Session Laboratory For Examiner’s Use 1 2 3 Total

2 9701/31/O/N/10 © UCLES 2010 For Examiner’s Use There are three questions on this paper. Question 2 should not be the last question attempted. 1 You are to determine the concentration of hydrochloric acid, which supplies the H+ ions in the following reaction. IO3 –(aq) + 5I–(aq) + 6H+(aq) 3H2O(l) + 3I2(aq) In the presence of an excess of IO3 – ions and an excess of I– ions, the amount of I2 liberated is directly proportional to the amount of H+ ions present and can be determined by titration with sodium thiosulfate, Na2S2O3. You are provided with the following reactants. FA 1 hydrochloric acid FA 2 containing 15.0 g dm–3 sodium thiosulfate, Na2S2O3.5H2O aqueous potassium iodate(V), KIO3 aqueous potassium iodide, KI (a) Method • Fill a burette with FA 2. • Pipette 25.0 cm3 of FA 1 into the conical flask. • Use a 25 cm3 measuring cylinder to add to the flask 10 cm3 of aqueous potassium iodate(V) and 10 cm3 of aqueous potassium iodide. There is an excess of each of these reagents. • Place the flask on a white tile. • Titrate the liberated iodine with FA 2. • During the titration the colour of the iodine in the solution will fade from red-brown to orange to yellow. The end-point occurs when the solution just goes colourless with the addition of a single drop of FA 2. • You should perform a rough titration. In the space below record your burette readings for this rough titration. The rough titre is … cm3 • Carry out as many accurate titrations as you think necessary to obtain consistent results. • Record in a suitable form below all of your burette readings and the volume of FA 2 added in each accurate titration. • Make certain any recorded results show the precision of your practical work. [7] I II III IV V VI VII

3 9701/31/O/N/10 © UCLES 2010 [Turn over For Examiner’s Use (b) From your titration results obtain a suitable value to be used in your calculation. Show clearly how you have obtained this value. 25.0 cm3 of FA 1 require … cm3 of FA 2. [1] Calculations Show your working and appropriate significant figures in the final answer to each step of your calculations. (c) (i) Calculate the concentration, in mol dm–3, of the sodium thiosulfate in FA 2. FA 2 contains 15.0 g dm–3 Na2S2O3.5H2O. [Ar: H, 1.0; O, 16.0; Na, 23.0; S, 32.1] The concentration of sodium thiosulfate in FA 2 is … mol dm–3. (ii) Calculate how many moles of Na2S2O3 are contained in the volume of FA 2 recorded in (b). … mol of Na2S2O3 (iii) Calculate how many moles of iodine, I2 reacted with the Na2S2O3 in (ii). 2Na2S2O3(aq) + I2(aq) Na2S4O6(aq) + 2NaI(aq) … mol of iodine reacted with the sodium thiosulfate. (iv) Calculate how many moles of hydrochloric acid, HCl, reacted with an excess of potassium iodate(V) and an excess of potassium iodide to produce the amount of iodine calculated in (iii). IO3 –(aq) + 5I–(aq) + 6H+(aq) 3H2O(l) + 3I2(aq) … mol of HCl produced the amount of iodine calculated in (iii). I II III IV V

4 9701/31/O/N/10 © UCLES 2010 For Examiner’s Use (v) Calculate the concentration, in mol dm–3, of HCl in FA 1. The concentration of HCl in FA 1 is … mol dm–3. [5] (d) Each reading with a burette has a maximum error of ±0.05 cm3. Grade B volumetric (bulb) pipettes are calibrated to ±0.06 cm3. (i) Calculate the maximum error in the volume run from the burette recorded in any titration. The maximum error is … cm3. (ii) Express the maximum error calculated in (i) as a percentage error for the volume calculated in (b). The maximum error is … %. (iii) Calculate the percentage error when 25.0 cm3 of FA 1 was pipetted into the conical flask. The error was … %. [2] [Total: 15]

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6 9701/31/O/N/10 © UCLES 2010 For Examiner’s Use 2 FA 3 is powdered basic copper(II) carbonate, a hydrated mixture of copper(II) carbonate and copper(II) hydroxide. The approximate formula for the basic carbonate is CuCO3.Cu(OH)2.H2O. When heated, basic copper(II) carbonate decomposes. CuCO3.Cu(OH)2.H2O(s) 2CuO(s) + CO2(g) + 2H2O(g) You are to determine the change in mass as the solid is heated and decomposed. (a) Method – Read through the instructions before starting any practical work. • Record all weighings in an appropriate form in the space below. • Weigh and record the mass of an empty boiling-tube. • Tip the contents of the tube labelled FA 3 into the weighed boiling-tube. Reweigh and record the total mass of the boiling-tube and FA 3. • Heat FA 3 in the boiling-tube very gently until the vigorous decomposition of the copper carbonate has stopped; then heat more strongly for 1 to 2 minutes. Take care not to lose any solid from the tube during the initial heating. • Warm the upper parts of the boiling-tube to evaporate any water that may have condensed while heating the carbonate. • Place the hot tube on a heat-proof mat and leave to cool. • You are advised to continue with part (d) of this question or to start another question while the tube cools. • When cool, reweigh the boiling-tube and the residual copper(II) oxide. • Reheat, cool and reweigh the tube until you are satisfied decomposition is complete. Results In an appropriate form, in the space below, record all of your balance readings, the mass of basic copper(II) carbonate and the mass of residual copper oxide. [6] I II III IV V VI

7 9701/31/O/N/10 © UCLES 2010 [Turn over For Examiner’s Use Calculations (b) Calculate the loss in mass during the experiment as a percentage of the mass of solid heated. [1] (c) The theoretical loss in mass is 33.5%. The proportions of CuCO3 and Cu(OH)2 in the basic carbonate can vary from the 1:1 ratio given in the formula. Make use of the following information to account for the difference between the value you have calculated in (b) and the theoretical percentage loss in mass. 1 mol CuCO3(s) 1 mol CO2(g) 1 mol Cu(OH)2(s) 1 mol H2O(g) Assume that 1 mol of any sample of the solid basic carbonate contains 1 mol H2O. [Mr: CO2, 44.0; H2O, 18.0] … … … [1] (d) Add to the diagram below additional standard laboratory apparatus that would enable you to collect and measure the volume of carbon dioxide evolved in the experiment. Ensure that your apparatus does not also collect and measure any of the water vapour evolved. heat [2] [Total: 10]

8 9701/31/O/N/10 © UCLES 2010 For Examiner’s Use 3 FA 4, FA 5, FA 6 and FA 7 are aqueous solutions each containing one of the ions Al 3+, Mg2+, Pb2+, Zn2+. You will carry out the following tests on each of the solutions. At each stage of any test you are to record details of the following. • colour changes seen • the formation of any precipitate • the solubility of such precipitates in an excess of the reagent added Where gases are released they should be identified by a test, described in the appropriate place in your observations. You should indicate clearly at what stage in a test a change occurs. Marks are not given for chemical equations. No additional tests for ions present should be attempted. (a) Carry out the following tests. Record your observations in the spaces provided in the table. You should rinse and reuse test-tubes where possible. test observations FA 4 FA 5 FA 6 FA 7 (i) To 1 cm depth of solution in a test- tube add 1 cm depth of aqueous sodium hydroxide. Swirl the tube, then add a further 2 cm depth of aqueous sodium hydroxide. (ii) To 1 cm depth of solution in a test- tube add 1 cm depth of aqueous ammonia. Swirl the tube, then add a further 2 cm depth of aqueous ammonia. (iii) To 1 cm depth of solution in a test- tube add 1 cm depth of aqueous potassium iodide. [4] I II III IV

9 9701/31/O/N/10 © UCLES 2010 [Turn over For Examiner’s Use (b) Use the Qualitative Analysis Notes on page 11 to identify the cation present in each of the solutions. Complete the table below to identify each ion and to give supporting evidence from your observations. solution cation supporting evidence FA 4 FA 5 FA 6 FA 7 [4] Do not carry out the following test. (c) Use the Qualitative Analysis Notes on pages 11 and 12 to select a further reagent that could be used to confirm the presence of Pb2+ in one of the solutions FA 4, FA 5, FA 6 and FA 7. The reagent is … . [1] I II III IV

10 9701/31/O/N/10 © UCLES 2010 For Examiner’s Use (d) FA 8 contains aqueous copper(II) ions. Carry out the following tests and make careful observations of all that happens in each experiment. test observations (i) To 2 cm depth of FA 8 in a boiling- tube add 1 spatula measure of zinc metal powder. Leave to stand for 1 minute, then add 2 cm depth of distilled water and leave to stand for a further 2 minutes. (ii) To 1 cm depth of FA 8 in a test-tube add 1 cm depth of concentrated hydrochloric acid. (Care: corrosive) Retain the mixture for use in (iii). (iii) Using a dropping pipette transfer 1 cm depth of the solution in (ii) into another test-tube. Add 1 cm depth of water and shake the tube. [5] (e) From your observations in (d)(i) complete the equation below: Cu2+(aq) + Zn(s) [1] [Total: 15] I II III IV V

11 9701/31/O/N/10 © UCLES 2010 [Turn over Qualitative Analysis Notes Key: [ ppt. = precipitate ] 1 Reactions of aqueous cations ion reaction with NaOH(aq) NH3(aq) aluminium, Al 3+(aq) white ppt. soluble in excess white ppt. insoluble in excess ammonium, NH4 +(aq) no ppt. ammonia produced on heating barium, Ba2+(aq) no ppt. (if reagents are pure) no ppt. calcium, Ca2+(aq) white ppt. with high [Ca2+(aq)] no ppt. chromium(III), Cr3+(aq) grey-green ppt. soluble in excess giving dark green solution grey-green ppt. insoluble in excess copper(II), Cu2+(aq) pale blue ppt. insoluble in excess blue ppt. soluble in excess giving dark blue solution iron(II), Fe2+(aq) green ppt. turning brown on contact with air insoluble in excess green ppt. turning brown on contact with air insoluble in excess iron(III), Fe3+(aq) red-brown ppt. insoluble in excess red-brown ppt. insoluble in excess lead(II), Pb2+(aq) white ppt. soluble in excess white ppt. insoluble in excess magnesium, Mg2+(aq) white ppt. insoluble in excess white ppt. insoluble in excess manganese(II), Mn2+(aq) off-white ppt. rapidly turning brown on contact with air insoluble in excess off-white ppt. rapidly turning brown on contact with air insoluble in excess zinc, Zn2+(aq) white ppt. soluble in excess white ppt. soluble in excess [Lead(II) ions can be distinguished from aluminium ions by the insolubility of lead(II) chloride.]

12 9701/31/O/N/10 © UCLES 2010 2 Reactions of anions ion reaction carbonate, CO3 2– CO2 liberated by dilute acids chromate(VI), CrO4 2– (aq) yellow solution turns orange with H+(aq); gives yellow ppt. with Ba2+(aq); gives bright yellow ppt. with Pb2+(aq) chloride, Cl– (aq) gives white ppt. with Ag+(aq) (soluble in NH3(aq)); gives white ppt. with Pb2+(aq) bromide, Br– (aq) gives cream ppt. with Ag+(aq) (partially soluble in NH3(aq)); gives white ppt. with Pb2+(aq) iodide, I– (aq) gives yellow ppt. with Ag+(aq) (insoluble in NH3(aq)); gives yellow ppt. with Pb2+(aq) nitrate, NO3 – (aq) NH3 liberated on heating with OH–(aq) and Al foil nitrite, NO2 – (aq) NH3 liberated on heating with OH–(aq) and Al foil; NO liberated by dilute acids (colourless NO → (pale) brown NO2 in air) sulfate, SO4 2– (aq) gives white ppt. with Ba2+(aq) or with Pb2+(aq) (insoluble in excess dilute strong acid) sulfite, SO3 2– (aq) SO2 liberated with dilute acids; gives white ppt. with Ba2+(aq) (soluble in excess dilute strong acid) 3 Tests for gases gas test and test result ammonia, NH3 turns damp red litmus paper blue carbon dioxide, CO2 gives a white ppt. with limewater (ppt. dissolves with excess CO2) chlorine, Cl2 bleaches damp litmus paper hydrogen, H2 “pops” with a lighted splint oxygen, O2 relights a glowing splint sulfur dioxide, SO2 turns acidified aqueous potassium dichromate(VI) from orange to green Permission to reproduce items where third-party owned material protected by copyright is included has been sought and cleared where possible. Every reasonable effort has been made by the publisher (UCLES) to trace copyright holders, but if any items requiring clearance have unwittingly been included, the publisher will be pleased to make amends at the earliest possible opportunity. University of Cambridge International Examinations is part of the Cambridge Assessment Group. Cambridge Assessment is the brand name of University of Cambridge Local Examinations Syndicate (UCLES), which is itself a department of the University of Cambridge.

UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS GCE Advanced Subsidiary Level and GCE Advanced Level MARK SCHEME for the October/November 2010 question paper for the guidance of teachers 9701 CHEMISTRY 9701/31 Paper 3 (Advanced Practical Skills), maximum raw mark 40 This mark scheme is published as an aid to teachers and candidates, to indicate the requirements of the examination. It shows the basis on which Examiners were instructed to award marks. It does not indicate the details of the discussions that took place at an Examiners’ meeting before marking began, which would have considered the acceptability of alternative answers. Mark schemes must be read in conjunction with the question papers and the report on the examination. • CIE will not enter into discussions or correspondence in connection with these mark schemes. CIE is publishing the mark schemes for the October/November 2010 question papers for most IGCSE, GCE Advanced Level and Advanced Subsidiary Level syllabuses and some Ordinary Level syllabuses.

Page 2 Mark Scheme: Teachers’ version Syllabus Paper GCE A/AS LEVEL – October/November 2010 9701 31 © UCLES 2010 Question Sections Indicative material Mark 1 (a) PDO layout I Volume given for Rough titre and accurate titre details tabulated. 1 MMO Collection II In the correct spaces, records Initial and final burette readings for Rough titre and; Initial and final burette readings and, volume of FB 2 added recorded for each accurate titre Headings should match readings. Do not award this mark if: 50(.00) is used as an initial burette reading; More than one final burette reading is 50.(00); Any burette reading is greater than 50.(00) 1 MMO Decisions III Has two uncorrected, accurate titres within 0.1 cm3 Do not award this mark if having performed two titres within 0.1 cm3 a further titration is performed which is more than 0.10 cm3 from the closer of the initial two titres, unless a fourth titration, within 0.1 cm3 of the third titration or of the first two titres has also been carried out. 1 PDO Recording IV All accurate burette readings (initial and final) recorded to nearest 0.05 cm3. Assessed on burette readings only. 1 MMO Quality V, VI and VII Round any burette readings to the nearest 0.05 cm3 Check and correct subtractions in the titre table. Select the “best”titre using the hierarchy: two identical; titres within 0.05 cm3, titres within 0.10 cm3 etc. Award V, VI and VII for a difference to Supervisor within 0.20 cm3 Award V and VI only for a difference of 0.20+ cm3 – 0.40 cm3 Award V only for a difference of 0.40+ cm3 - 0.80 cm3 If the selected “best” titres are > 0.50 cm3 apart, cancel one of the Q marks awarded. 3 [7]

Page 3 Mark Scheme: Teachers’ version Syllabus Paper GCE A/AS LEVEL – October/November 2010 9701 31 © UCLES 2010 (b) ACE Interpretation Calculates the mean, correct to 2 decimal places (third decimal place maybe rounded to the nearest 0.05 cm3) from any accurate titres within 0.20 cm3. A mean of exactly .x25 or .x75 is allowed but the candidate may round up or down to the nearest 0.05 cm3. If ALL burette readings are given to 1 decimal place then the mean can be given to 1 decimal place if numerically correct without rounding. Mean of 24.3 and 24.4 = 24.35 (✓) Mean of 24.3 and 24.4 = 24.4 () Mean of 24.3 and 24.5 = 24.4 (✓) Titres to be used in calculating the mean must be clearly shown – in an expression or ticked in the titration table. 1 [1] (c) ACE Interpretation No additional factor/expression is allowed in any step If an answer, with no working, is given in any section allow if correct. I Uses 15.0/248.2 only in step (i) If no working shown accept only the following evaluated answers: (0.060, 0.0604 or 0.06044) 1 II Uses answer (i) × cand average titre/1000 in step (ii) and answer (iv) × 1000/25 in step (v) 1 1 III Uses answer (ii) × ½ in step (iii), and answer (iii) × 2 in step (iv) 1 PDO Display IV Appropriate working shown in a minimum of three sections. To include equations as steps for the working mark; In (iii) must see x2 or x0.5. In (iv) must see multiplication or division by 6, 1.2 or 2. 1:6 for IO3 –/6H+, 1:1.2 for 5I –/6H+, 1:2 for 6H+/3I2 1 V 3 to 5 significant figures in final answers to all sections attempted – minimum of three final answers required to qualify for the award of this mark. 1 [5]

Page 4 Mark Scheme: Teachers’ version Syllabus Paper GCE A/AS LEVEL – October/November 2010 9701 31 © UCLES 2010 (d) ACE Interpretation Gives 0.1(0) cm3 as the maximum error in (i). Ignore any sign and the expression 0.1/cand titre in (b) × 100 in (ii) Evaluates 0.06/25.0 × 100 in step (iii) Accept only 0.240 or 0.24, or rounded to 0.2 provided 0.24 has been seen in the working. 1 1 [2] [Total: 15]

Page 5 Mark Scheme: Teachers’ version Syllabus Paper GCE A/AS LEVEL – October/November 2010 9701 31 © UCLES 2010 2 (a) PDO Layout I Records at least four different balance readings and at least one mass of solid/gas Accept 0.0(0X) g as the mass of the empty tube or a statement that the tube is tared. 1 PDO Recording II Gives all appropriate headings and units when recording results. Do not accept mass of empty tube as 0.0(00)g here unless tube is described as tared. (minimum of three pieces of information) 1 III All recorded balance readings consistent to at least 1 decimal place. (minimum of three balance readings) 1 MMO Decisions IV Evidence of reheating to “constant” mass. For balances reading to 1 d.p. two masses must be identical For 2 or 3 d.p.balances, two masses must be within 0.05 g 1 MMO Quality V and VI Check and correct all subtractions in the results table. Calculate mass heated/mass of residue to 3 significant figures. Compare to Supervisor standard or standard value of 1.45. Award V and VI for a difference up to 0.15 Award V only for a difference of 0.15+ to 0.30 Where a candidate repeats the experiment use cumulative masses of FA 3 and residue. Where masses of FA 3 and residue cannot be checked, accept candidate values to calculate the ratio. 2 [6] (b) ACE Interpretation Evaluates cand mass loss from (a)/cand mass of FA 3 correct to 2–4 significant figures. Where mass loss or mass of FA 3 is not given in (a), check, from balance readings, the values. A candidate who incorrectly describes the mass of the residue as the mass loss in tabulated results in (a) may “correct” the error and use the correct mass loss here. 1 [1]

Page 6 Mark Scheme: Teachers’ version Syllabus Paper GCE A/AS LEVEL – October/November 2010 9701 31 © UCLES 2010 (c) ACE Conclusions Uses Mr (values) of CO2 or H2O to justify how the ratio of CuCO3 to Cu(OH)2 affects the mass loss. If % loss is too high – more CuCO3 If % loss is too low – more Cu(OH)2 1 [1] (d) ACE Improvements Draws apparatus showing the collection of carbon dioxide in a syringe or in a burette or measuring cylinder inverted over water. Allow use of an inverted tube if graduations are shown or it is suitably labelled. All apparatus should be recognisable from the drawing or appropriately labelled. 1 Shows, in the diagram, an effective method of removing water vapour. Named reagent; e.g. (concentrated H2SO4, CaCl2, silica gel, (CaO), anhydrous CuSO4. or stated purpose of an un-named reagent given. Allow also a suitable reflux arrangement, returning water to the heated tube. or a statement that water vapour condenses in a water bath. Do not accept a diagram showing the gas bubbling through water without some written indication that the water is a condenser. 1 [2] [Total: 10]

Page 7 Mark Scheme: Teachers’ version Syllabus Paper GCE A/AS LEVEL – October/November 2010 9701 31 © UCLES 2010 FA 4 is Al2(SO4)3(aq); FA 5 is ZnSO4(aq); FA 6 is Pb(NO3)2(aq); FA 7 is MgSO4(aq) 3 (a) MMO Collection 1 mark for correct observations in each of the vertical columns. or 1 mark for correct observations in each of the horizontal rows (i), (ii) and (iii). 3 mark maximum Mark the section by the method which gives the better mark. 4 [4] observations test FA 4 FA 5 FA 6 FA 7 (i) addition of NaOH white ppt white ppt white ppt white ppt further addition of NaOH ppt soluble ppt soluble ppt soluble ppt insoluble (ii) addition of NH3 white ppt white ppt white ppt white ppt further addition of NH3 ppt insoluble ppt soluble ppt insoluble ppt insoluble (iii) addition of KI no ppt, no reaction, colourless or yellow solution no ppt, no reaction, colourless or yellow solution yellow ppt no ppt, no reaction, colourless or yellow solution Minimum evidence required in observations for the ion identity marks I, II and III in (b) In some cases, identification may be allowed from incomplete observations. There must, however, be no observations that are contrary to those expected with any “correctly” identified ion. The same criteria will be applied to “candidate’s supporting evidence in awarding mark IV. Candidates are not permitted to introduce (from the Qualitative Analysis Notes) supporting evidence that is not given in the observations. Precipitate colour need not be mentioned in supporting evidence. Al3+ (white) precipitate, soluble in (excess) NaOH, if yellow ppt with KI Zn2+ (white) precipitate, soluble in (excess) NH3(aq) Pb2+ Yellow precipitate with KI Mg2+ (white) precipitate, insoluble in (excess) NaOH

Page 8 Mark Scheme: Teachers’ version Syllabus Paper GCE A/AS LEVEL – October/November 2010 9701 31 © UCLES 2010 FA 4 is Al2(SO4)3(aq); FA 5 is ZnSO4(aq); FA 6 is Pb(NO3)2(aq); FA 7 is MgSO4(aq) ACE Conclusions (b) Do not accept any ion other than Al 3+, Zn2+, Pb2+or Mg2+ in any section. Marks I to III Ions must be correct, including charge, if a symbol has been given. – no ecf in this section. Award I only if one ion only is identified from correct observations. Award I and II if two ions only are identified from correct observations. Award I, II and III if all four cations are identified from correct observations. The 4th cation may be identified by elimination from incomplete supporting evidence. Award mark IV if the supporting evidence fits the ion identified and the practical performed for at least three of the four ions. Allow ecf on ion order on mark IV. 1 1 1 1 1 [4] (c) MMO Decisions Selects sodium or potassium chromate(VI), sulfuric acid or hydrochloric acid soln containing one of the following named ions or formula given followed by (aq): CrO4 2-, SO4 2-, Cl -, Br- but not I–, soln containing CrO4 2- ions, H2SO4, HCl, [1]

Page 9 Mark Scheme: Teachers’ version Syllabus Paper GCE A/AS LEVEL – October/November 2010 9701 31 © UCLES 2010 FA 8 is CuSO4(aq) (d) MMO Collection I Records blue colour of solution fading/disappearing on adding zinc powder in (i) If no reaction with Zn(s) is reported do not allow blue to light blue solution. 1 II Records a temperature rise in (i) Accept reaction is exothermic/produces heat 1 III Records a red-brown, orange-brown, brown or black solid in (i) 1 IV Observes a green, lime green, fluorescent green or yellow-green solution in (ii) 1 V Observes solution turning blue, or blue solution in (iii) if solution green in (ii) or solution going towards blue in colour on adding water in (iii) If solution is not mentioned in (ii) or (iii) but colours are correct – award point V only. 1 [5] (e) ACE Conclusions Completes the equation: → Cu(s) + Zn2+(aq) State symbols required 1 [1] [Total: 15]