Cambridge A Level Chemistry 9701 — 2016 Feb/March Paper 2 · Variant 2

READ THESE INSTRUCTIONS FIRST Write your Centre number, candidate number and name on all the work you hand in. Write in dark blue or black pen. You may use an HB pencil for any diagrams or graphs. Do not use staples, paper clips, glue or correction fluid. DO NOT WRITE IN ANY BARCODES. Answer all questions. Electronic calculators may be used. You may lose marks if you do not show your working or if you do not use appropriate units. A Data Booklet is provided. 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. CHEMISTRY 9701/22 Paper 2 AS Level Structured Questions February/March 2016 1 hour 15 minutes Candidates answer on the Question Paper. Additional Materials: Data Booklet Cambridge International Examinations Cambridge International Advanced Subsidiary and Advanced Level This document consists of 13 printed pages and 3 blank pages. [Turn over IB16 03_9701_22/5RP © UCLES 2016 *8398966658*

2 9701/22/F/M/16 © UCLES 2016 Answer all the questions in the spaces provided. 1 This question is about Period 3 elements and their compounds. (a) Give an explanation for each of the following statements. (i) The atomic radius decreases across Period 3 (Na to Ar). … … … … [2] (ii) The first ionisation energy of sulfur is lower than that of phosphorus. … … … … [2] (iii) Sodium is a better electrical conductor than phosphorus. … … … … [2] (iv) Magnesium is a better electrical conductor than sodium. … … [1]

3 9701/22/F/M/16 © UCLES 2016 [Turn over (b) The flow chart below shows a series of reactions. A(aq) white precipitate, E(s) B(g) + C(g) D(g) + Mg(s) HNO3(aq) reagent X(aq) heat MgO(s) + H2O(g) + (i) Give the formula of each of the compounds A to D. A … B … C … D … [4] (ii) E reacts with dilute aqueous acid to produce a gas that turns limewater cloudy. Suggest the identity of reagent X. … [1] [Total: 12]

4 9701/22/F/M/16 © UCLES 2016 2 Spathose is an iron ore that contains iron(II) carbonate, FeCO3. The percentage of iron(II) carbonate in spathose can be determined by titration with acidified potassium dichromate(VI) solution using a suitable indicator. The ionic equation is shown below. Cr2O7 2–(aq) + 14H+(aq) + 6Fe2+(aq) → 2Cr3+(aq) + 6Fe3+(aq) + 7H2O(l) (a) A 5.00 g sample of spathose was reacted with excess concentrated hydrochloric acid and then filtered. The filtrate was made up to 250 cm3 in a volumetric flask with distilled water. A 25.0 cm3 sample of the standard solution required 27.30 cm3 of 0.0200 mol dm–3 dichromate(VI) solution for complete reaction. (i) Calculate the amount, in moles, of dichromate(VI) ions used in the titration. amount = … mol [1] (ii) Use your answer to (i) to calculate the amount, in moles, of Fe2+ present in the 25.0 cm3 sample. amount = … mol [1] (iii) Use your answer to (ii) to calculate the amount, in moles, of Fe2+ present in the 250 cm3 volumetric flask. amount = … mol [1] (iv) Use your answer to (iii) to calculate the mass of iron(II) carbonate present in the sample of spathose. mass = … g [2] (v) Calculate the percentage of iron(II) carbonate in the sample of spathose. percentage of iron(II) carbonate = … % [1]

5 9701/22/F/M/16 © UCLES 2016 [Turn over (b) Iron ores containing iron(III) compounds can be analysed using a similar method. A standard solution of an aqueous iron(III) compound is reacted with aqueous tin(II) chloride. Aqueous tin(IV) chloride and aqueous iron(II) chloride are the products of this reaction. (i) Write an ionic equation for this reaction. Do not include state symbols. … [2] (ii) Any excess tin(II) chloride can be removed by reaction with HgCl 2(aq). A white precipitate of Hg2Cl 2 is produced. Complete the equation for this reaction. …(…) + …HgCl 2(aq) → SnCl 4(…) + Hg2Cl 2(…) [2] [Total: 10]

6 9701/22/F/M/16 © UCLES 2016 3 Over one million tonnes of hydrogen cyanide, HCN, are produced each year using the Andrussow process. The overall equation for the reaction is shown. CH4(g) + NH3(g) + 1 2 1 O2(g) HCN(g) + 3H2O(g) (a) (i) Draw a dot-and-cross diagram to represent the bonding in a molecule of ammonia, NH3, and state the shape of the molecule. shape of molecule … [3] (ii) A molecule of hydrogen cyanide, HCN, is shown. N C H The bonding between the carbon and nitrogen atoms consists of one sigma (σ) bond and two pi (π) bonds. Sketch the shape of the sigma bond and one of the pi bonds in the space below. Show clearly the position of the atomic nuclei in each diagram. sigma (σ) pi (π) [2]

7 9701/22/F/M/16 © UCLES 2016 [Turn over (b) The reaction exists as a dynamic equilibrium. (i) Explain what is meant by the term dynamic equilibrium. … … [1] (ii) State and explain how the amounts of the chemicals present in the equilibrium mixture will change when the pressure is increased. … … … [2] (c) The process uses a platinum catalyst, which increases the rate of reaction. Sketch a Boltzmann distribution on the axes given below and use your diagram to explain how the platinum catalyst increases the rate of the reaction. number of molecules molecular energy … … … … [3]

8 9701/22/F/M/16 © UCLES 2016 (d) The reaction of hydrogen cyanide with propanone is an important first step in many organic syntheses. (i) Give the full name of the mechanism of this reaction. … [1] (ii) Complete the diagram to show the mechanism of the reaction of hydrogen cyanide with propanone. Draw the structure of the intermediate and the product of the reaction. Include all relevant charges, partial charges, curly arrows and lone pairs. O C –CN CH3 H3C [5] [Total: 17]

9 9701/22/F/M/16 © UCLES 2016 [Turn over Question 4 starts on the next page.

10 9701/22/F/M/16 © UCLES 2016 4 The following compounds were all found to be components of a sample of petrol. CH3(CH2)2CH3 (CH3)3CCH2CH(CH3)2 H C H H J G H3C CH3 H3C C OH (a) (i) Give the molecular formula of compound G. … [1] (ii) Give the empirical formula of compound H. … [1] (iii) Draw the skeletal formula of compound J. [1] (b) Write an equation to represent the complete combustion of compound H. … [1] (c) Fossil fuels are often contaminated with sulfur. State and explain why supplies of fossil fuels that contain sulfur pose a problem to the environment. … … … [2]

11 9701/22/F/M/16 © UCLES 2016 [Turn over (d) The boiling points of compounds G, H and J are shown below. compound G H J boiling point / °C 0 99 112 Explain the differences in the boiling points of the three compounds. … … … … … … … [4] (e) Compound J can be produced from 2-chloro-3-methylbutane, C5H11Cl. Give the reagent(s) and conditions for this reaction. … [1] [Total: 11]

12 9701/22/F/M/16 © UCLES 2016 5 Some reactions of compound P, C5H8O, are shown. H2(g) Ni(s) catalyst OH–(aq) I2(aq) compound Q compound R compound S compound P compound T + O O –O cold, acidified KMnO4(aq) NaBH4 (a) (i) Give the structures for organic compounds Q, R, S and T. Q T R S [4]

13 9701/22/F/M/16 © UCLES 2016 [Turn over (ii) Give the systematic name of compound P. … [1] (iii) What would you observe when compound P is reacted with 2,4-dinitrophenylhydrazine (2,4-DNPH)? … [1] (b) Compound U contains a chiral centre and has the same molecular formula as compound P, C5H8O. • Compound U readily decolourises a sample of bromine water. • Compound U does not show cis-trans isomerism. • When compound U is heated under reflux in the presence of excess acidified potassium dichromate(VI), the organic product gives the infra-red spectrum shown. infra-red spectrum of product 4000 3000 2000 wavenumber / cm–1 1000 1500 500 transmittance / % 100 50 0 Use the information given to suggest a structure for compound U. Explain your answer. [4] [Total: 10]

14 9701/22/F/M/16 © UCLES 2016 BLANK PAGE

15 9701/22/F/M/16 © UCLES 2016 BLANK PAGE

16 9701/22/F/M/16 © UCLES 2016 BLANK PAGE 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. To avoid the issue of disclosure of answer-related information to candidates, all copyright acknowledgements are reproduced online in the Cambridge International Examinations Copyright Acknowledgements Booklet. This is produced for each series of examinations and is freely available to download at www.cie.org.uk after the live examination series. 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.

® IGCSE is the registered trademark of Cambridge International Examinations. CAMBRIDGE INTERNATIONAL EXAMINATIONS Cambridge International Advanced Subsidiary and Advanced Level MARK SCHEME for the March 2016 series 9701 CHEMISTRY 9701/22 Paper 2 (AS Structured Questions), maximum raw mark 60 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 should be read in conjunction with the question paper and the Principal Examiner Report for Teachers. Cambridge will not enter into discussions about these mark schemes. Cambridge is publishing the mark schemes for the March 2016 series for most Cambridge IGCSE® and Cambridge International A and AS Level components.

Page 2 Mark Scheme Syllabus Paper Cambridge International AS/A Level – March 2016 9701 22 © Cambridge International Examinations 2016 Question Answer Mark Total 1 (a) (i) greater attractive force OR greater force between nucleus and (outer) electrons proton number / atomic number / nuclear charge increases across period AND electrons occupy same shell / shielding roughly constant [1] [1] [2] (ii) sulfur’s electron removed from full (3p) orbital OR sulfur has two electrons in the same orbital electron–electron repulsion (reduces energy required) [1] [1] [2] (iii) sodium has mobile / free electrons / electrons free (to move throughout the structure) phosphorus is simple / covalent / molecular [1] [1] [2] (iv) magnesium has two free / delocalised / outer / valence electrons per atom OR more free / delocalised / outer electrons than sodium [1] [1] (b) (i) A = Mg(NO3)2 B = H2 C = NO2 OR O2 D = O2 OR NO2 [1] [1] [1] [1] [4] (ii) any Group I carbonate OR ammonium carbonate [1] [1] [12] 2 (a) (i) 27.30 × 0.020 1000 =5.46 × 10–4 (mol) [1] [1] (ii) (i) × 6 =3.28 × 10–3 (mol) [1] [1]

Page 3 Mark Scheme Syllabus Paper Cambridge International AS/A Level – March 2016 9701 22 © Cambridge International Examinations 2016 Question Answer Mark Total (iii) (ii) × 250 25.00 =3.28 × 10–2 (mol) [1] [1] (iv) Mr of FeCO3 =55.8 + 12.0 + 3(16.0) = 115.8 (iii) × Mr(FeCO3) =3.79g [1] [1] [2] (v) ×100% 5.00 (iv) = 75.9% [1] [1] (b) (i) 2Fe3+ + Sn2+ → 2Fe2+ + Sn4+ species balancing [1] [1] [2] (ii) SnCl 2(aq) + 2HgCl 2(aq) → SnCl 4(aq) + Hg2Cl 2(s) SnCl 2 AND 2 state symbols [1] [1] [2] [10] 3 (a) (i) three bonding pairs lone pair AND octet shape = (trigonal) pyramidal [1] [1] [1] [3]

Qu ( uest (b) tion (ii) (i) (ii) sig O pi( forw OR the M1 M2 OR equ gma R (π) b ward R e rate = d = le R uilib P a(σ) bon d an e of decr eft-h rium age bon d nd b f forw reas hand m sh e 4 nd back war sed y d sid hifts kwar rd an yield de h to t rd re nd b d of has the l Ca eact back f pro few left amb tion kwa oduc wer m brid s oc ard r cts / mole ge © ccur eac less es o Inte © Ca rring ction s pro of ga erna ambr g at ns ar odu as Mar ation ridge sam re e cts rk S nal e Int A me r equa form Sche AS/ terna Answ rate al med eme /A L ation wer d / o e Leve nal E r ra el – Exam Ma mina arch ation h 20 ns 20 16 016 Sy 9 yllab 970 bus 1 Pap 22 per 2 Mark [1] [1] [1] [1] [1] k Tota [2] [1] [2] al

Page 5 Mark Scheme Syllabus Paper Cambridge International AS/A Level – March 2016 9701 22 © Cambridge International Examinations 2016 Question Answer Mark Total (c) M1 = correct Boltzmann curve M2, M3 any 2 from: • line for both Ea values or statement in text that catalyst lowers Ea • (catalyst) increases proportion/number of molecules/particles with energy ⩾ activation energy • so more frequent successful collisions [1] [1] [1] [3] Ea with catalyst Ea without catalyst molecularenergy number of molecules

Page 6 Mark Scheme Syllabus Paper Cambridge International AS/A Level – March 2016 9701 22 © Cambridge International Examinations 2016 Question Answer Mark Total (d) (i) nucleophilic addition [1] [1] (ii) correct dipole on carbonyl curly arrow from lone pair on CN– AND from C=O to O correct intermediate curly arrow from lone pair on O– to H+ correct product [1] [1] [1] [1] [1] [5] [17] 4 (a) (i) C4H10 [1] [1] (ii) C4H9 [1] [1] (iii) [1] [1] (b) C8H18 + 12½O2 → 8CO2 + 9H2O [1] [1] (c) sulfur dioxide would be produced on combustion (which contributes to) acid rain [1] [1] [2]

Page 7 Mark Scheme Syllabus Paper Cambridge International AS/A Level – March 2016 9701 22 © Cambridge International Examinations 2016 Question Answer Mark Total (d) M1 = H has more / greater / stronger van der Waals’ / intermolecular forces than G / ora M2 = (because) H has more electrons (than G) M3 = J has hydrogen bonding (between molecules) M4 = strong(er) / great(er) forces require AND high / more energy to overcome [1] [1] [1] [1] [4] (e) NaOH(aq) [1] [1] [11] 5 (a) (i) Q R S T [1] [1] [1] [1] [4] (ii) pent-3-en(e)-2-one OR 3-penten-2-one [1] [1] (iii) red / orange / yellow precipitate / solid [1] [1]

Page 8 Mark Scheme Syllabus Paper Cambridge International AS/A Level – March 2016 9701 22 © Cambridge International Examinations 2016 Question Answer Mark Total (b) This question was discounted. M1 = decolourises bromine / 1500–1600 cm–1 = alkene M2 = absorption at 1700 cm–1 is C=O AND (very) broad absorption at 2500–3000 cm–1 is O—H = carboxylic acid M3 = no cis-trans so terminal alkene OR chiral so contains a carbon atom with 4 different groups attached M4 = U is [1] [1] [1] [1] [4] [10]