Cambridge A Level Chemistry 9701 — 2016 Oct/Nov 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 October/November 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 10 printed pages and 2 blank pages. [Turn over IB16 11_9701_22/5RP © UCLES 2016 *8468970221*

2 9701/22/O/N/16 © UCLES 2016 Answer all the questions in the spaces provided. 1 A 0.50 g sample of a Group 2 metal, M, was added to 40.0 cm3 of 1.00 mol dm–3 hydrochloric acid (an excess). equation 1 M(s) + 2HCl (aq) → MCl 2(aq) + H2(g) (a) Calculate the amount, in moles, of hydrochloric acid present in 40.0 cm3 of 1.00 mol dm–3 HCl. amount = … mol [1] (b) When the reaction had finished, the resulting solution was made up to 100 cm3 in a volumetric flask. A 10.0 cm3 sample of the solution from the volumetric flask required 15.0 cm3 of 0.050 mol dm–3 sodium carbonate solution, Na2CO3, for complete neutralisation of the remaining hydrochloric acid. (i) Write the equation for the complete reaction of sodium carbonate with hydrochloric acid. … [1] (ii) Calculate the amount, in moles, of sodium carbonate needed to react with the hydrochloric acid in the 10.0 cm3 sample from the volumetric flask. amount = … mol [1] (iii) Calculate the amount, in moles, of hydrochloric acid in the 10.0 cm3 sample. amount = … mol [1] (iv) Calculate the total amount, in moles, of hydrochloric acid remaining after the reaction shown in equation 1. amount = … mol [1]

3 9701/22/O/N/16 © UCLES 2016 [Turn over (v) Use your answers to (a) and (b)(iv) to calculate the amount, in moles, of hydrochloric acid that reacted with the 0.50 g sample of M. amount = … mol [1] (vi) Use your answer to (v) and equation 1 to calculate the amount, in moles, of M in the 0.50 g sample. amount = … mol [1] (vii) Calculate the relative atomic mass, Ar, of M and identify M. Ar of M = … identity of M = … [2] [Total: 9]

4 9701/22/O/N/16 © UCLES 2016 2 Dinitrogen tetraoxide, N2O4, and nitrogen dioxide, NO2, exist in dynamic equilibrium with each other. N2O4(g) 2NO2(g) ∆H = +54 kJ mol–1 The energy profile for this reaction is shown. energy reaction pathway N2O4(g) 2NO2(g) (a) Add labelled arrows to the energy profile to indicate • the enthalpy change of the reaction, ∆H, • the activation energy of the forward reaction, Ea. [2] (b) 0.0500 mol of N2O4 was placed in a sealed vessel of volume 1.00 dm3, at a temperature of 50 °C and a pressure of 1.68 × 105 Pa. The mass of the resulting equilibrium mixture was 4.606 g. (i) Calculate the average molecular mass, Mr, of the resulting equilibrium mixture. Give your answer to three significant figures. Mr = … [2] (ii) The number of moles of N2O4 that dissociated can be represented by n. State, in terms of n, the amount, in moles, of NO2 in the equilibrium mixture. moles of NO2 = … [1]

5 9701/22/O/N/16 © UCLES 2016 [Turn over The number of moles of N2O4 remaining at equilibrium is (0.05 – n). (iii) State, in terms of n, the total amount, in moles, of gas in the equilibrium mixture. [1] (iv) State, in terms of n, the mole fraction of NO2 in the equilibrium mixture. [1] In this equilibrium mixture, the mole fraction of NO2 is 0.400. (v) Use your answers to (ii) and (iv) to calculate the amount in moles of each gas in the equilibrium mixture. Give your answers to three significant figures. amount of N2O4 = … mol amount of NO2 = … mol [2] (vi) Write the expression for the equilibrium constant, Kp, for this equilibrium. Kp = [1] (vii) Use the total pressure of the mixture, 1.68 × 105 Pa, to calculate the value of the equilibrium constant, Kp, and give its units. Kp = … units = … [3] [Total: 13]

6 9701/22/O/N/16 © UCLES 2016 3 The Periodic Table is arranged such that the properties of the elements show a number of trends. (a) A plot of the first ionisation energies for the first 18 elements is shown. 2500 2000 1500 1000 500 0 ionisation energy / kJ mol–1 2 4 6 8 10 atomic number 12 14 16 18 (i) Explain why the values show a general increase from atomic number 11 to 18. … … … [2] (ii) Explain the decreases in first ionisation energies between • atomic numbers 12 and 13, … … … • atomic numbers 15 and 16. … … … [4] (iii) Suggest an explanation for the trend in the first ionisation energies of the elements with atomic numbers 2, 10 and 18. … … … [2]

7 9701/22/O/N/16 © UCLES 2016 [Turn over (b) A plot of the melting points of the elements across the third period is shown. 11 12 13 14 atomic number 15 16 17 18 1800 1600 1400 1200 1000 800 600 400 200 0 melting point / K (i) Explain the increase in melting point from atomic number 11 to 12. … … … [2] (ii) Suggest a reason why the increase from atomic number 12 to 13 is much smaller than the increase from atomic number 11 to 12. … … [1] (iii) State and explain the pattern of the melting points from atomic number 15 to 18. … … … … [3] (iv) Explain why the element with atomic number 14 has a melting point so much higher than the rest of the elements in the third period. … … [1] [Total: 15]

8 9701/22/O/N/16 © UCLES 2016 4 In each section of this question the structural formula of an organic compound is shown. For each compound answer the questions about it. (a) CH3CH2CHBrCH3 (i) Name this compound. … [1] (ii) This compound shows stereoisomerism. Draw the two stereoisomers in the conventional way. [2] (iii) Give the structures of three other structural isomers of C4H9Br. [3] (b) (C2H5)3CBr (i) Name this compound. … [1] (ii) (C2H5)3CBr reacts with aqueous OH–. Complete the mechanism for this reaction including all necessary curly arrows, charges, partial charges and lone pairs. CH3CH2C CH3CH2 CH3CH2 Br [3] (iii) What type of mechanism occurs in (ii)? … [1]

9 9701/22/O/N/16 © UCLES 2016 [Turn over (c) CH3CH2CH2CHBrCH3 (i) Give the reagents and conditions necessary for the conversion of this compound into a mixture of alkenes. … … [2] (ii) Give the name of the mechanism for the conversion in (i). … [1] (iii) Draw the skeletal formulae of the three alkenes produced by the conversion in (i). [3] [Total: 17]

10 9701/22/O/N/16 © UCLES 2016 5 In each section of this question choose the answer or answers from the options listed. (a) Six particles are listed. H• H+ Cl • Cl – •CH3 +CH3 (i) Identify two particles produced during the reaction of methane and chlorine in the presence of UV light. … [1] (ii) Identify the two particles produced by the heterolytic fission of a bond in chloromethane. … [1] (b) Seven reaction types are listed. addition substitution oxidation elimination hydrolysis condensation reduction (i) Name the type of reaction involved when Tollens’ reagent is used to identify an aldehyde. … [1] (ii) Name the type of reaction involved in the test for a carbonyl group using 2,4-DNPH. … [1] (iii) Name the type of reaction involved in the reaction of a ketone with NaBH4. … [1] (iv) Name the type of reaction involved in the reaction of an aldehyde with HCN. … [1] [Total: 6]

11 9701/22/O/N/16 © UCLES 2016 BLANK PAGE

12 9701/22/O/N/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. This document consists of 8 printed pages. © UCLES 2016 [Turn over Cambridge International Examinations Cambridge International Advanced Subsidiary and Advanced Level CHEMISTRY 9701/22 Paper 2 AS Level Structured Questions October/November 2016 MARK SCHEME Maximum Mark: 60 Published 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 October/November 2016 series for most Cambridge IGCSE®, Cambridge International A and AS Level components and some Cambridge O Level components.

Page 2 Mark Scheme Syllabus Paper Cambridge International AS/A Level – October/November 2016 9701 22 © UCLES 2016 Question Answer Mark 1(a) 0.04 OR 4 ×10–2 1 1(b)(i) Na2CO3 + 2HCl Æ 2NaCl + CO2 + H2O 1 1(b)(ii) 0.00075 OR 7.5 × 10–4 1 1(b)(iii) 0.0015 OR 1.5 × 10–3 1 1(b)(iv) 0.015 OR 1.5 × 10–2 1 1(b)(v) 0.025 OR 2.5 × 10–2 1 1(b)(vi) 0.0125 OR 1.25 × 10–2 OR 0.013 OR 1.3 × 10–2 1 1(b)(vii) 40 Ca / calcium 1 1 Total: 9

Q 2 2 2 Question 2(a) Arro Arro 2(b)(i) Mr = = 2(b)(ii) 2n 2(b)(iii) 0.05 2(b)(iv) 2 (0.0 2(b)(v) N2O NO2 2(b)(vi) Kp = Page 3 ow vertically up f ow vertically up f = m R T p V × × × =  = 73.6 5 – n + 2n OR 0. 2n 5 + n) O4 = 0.0375 2 = 0.0250 = pNO2 2 pN2O4 Cambridge Inte from N2O4 line to from N2O4 line to 5 4.606 8.31 1.68 10 1 × × = × × × .05 + n Mark ernational AS/A o 2NO2 line labe o dashed line fro 3 323 10−   k Scheme A Level – Octob © UCLES 2016 Answer elled enthalpy ch om peak labelled ber/November 2 hange / ∆H d activation ene Syllabus 2016 9701 rgy / Ea s Paper 22 Mark 1 1 1 1 1 1 1 1 1 1

Page 4 Mark Scheme Syllabus Paper Cambridge International AS/A Level – October/November 2016 9701 22 © UCLES 2016 Question Answer Mark 2(b)(vii) (0.4 ×1.68 ×105)2/(0.6 ×1.68 × 105) OR 0.42 × 1.68 × 105/ 0.6 44800 OR 44.8 Pa OR kPa 1 1 1 Total: 13 Question Answer Mark 3(a)(i) Increasing nuclear attraction Increasing nuclear charge / number of protons AND constant / similar shielding / same shell 1 1 3(a)(ii) From 12 / Mg to 13 / Al: (Outer) electron in ‘13’ / Al in (3)p (whereas outer electron in ‘12’ / Mg in (3)s) (3p =) higher energy level / more shielded From 15 / P to 16 / S electron repulsion (‘16’ / S has a) pair of electrons in a (3)p orbital / a (3)p orbital is full ORA 1 1 1 1 3(a)(iii) (decreasing IE down Group 0) due to decreasing nuclear attraction increasing shielding / increasing number of shells / energy levels / increasing distance of (outer) electrons (from nucleus) 1 1

Page 5 Mark Scheme Syllabus Paper Cambridge International AS/A Level – October/November 2016 9701 22 © UCLES 2016 Question Answer Mark 3(b)(i) Increasing strength of / more energy needed to break (metallic) bonding / increasing strength of attraction between (cat)ion / nucleus and delocalised / free / sea of / cloud of electrons Increasing number of delocalised electrons / decreasing (cat)ion size / increasing charge / charge density of (cat)ion 1 1 3(b)(ii) Attraction for electrons too strong to fully delocalise all 3 in Al OR difference in size between 12/Mg2+ and 13/Al3+ is less than difference in size between 11/Na+ and 12/Mg2+ OR magnitude of increase in charge is less from 2+ to 3+ than from 1+ to 2+ 1 3(b)(iii) Increase (15 / P to 16 / S) then decrease (to 17 / Cl and 18 / Ar) OR general decrease (from 15 / P to 18 / Ar) with an increase from 15 / P to 16 / S OR S(8)>P(4)>Cl(2)>Ar (melting point depends on strength of) VdW / IMFs The greater the number of electrons in the molecule (atom for Ar) the greater the strength of VdW / IMFs OR the greater the melting point ora 1 1 1 3(b)(iv) Giant covalent (structure) / many (strong) covalent bonds (need breaking) 1 Total: 15

Page 6 Mark Scheme Syllabus Paper Cambridge International AS/A Level – October/November 2016 9701 22 © UCLES 2016 Question Answer Mark 4(a)(i) 2–bromobutane 1 4(a)(ii) e.g. of mirror images C H CH2 CH3 C H3 Br C H CH2 CH3 CH3 Br e.g. of swapped groups C H CH2 CH3 C H3 Br C Br CH2 CH3 C H3 H 1+1 4(a)(iii) CH3CH2CH2CH2Br (CH3)2CHCH2Br (CH3)3CBr 1 1 1 4(b)(i) 3-bromo-3-ethylpentane 1 4(b)(ii) C Br CH2 CH2 CH2 C H3 C H3 C H3 δ+ δ− C + CH2 CH2 CH2 C H3 C H3 C H3 O H - M1 = dipole and curly arrow from bond to (or just beyond) Br M2 = correct carbocation M3 = OH– with curly arrow from lone pair on O to C(+) 1 1 1 4(b)(iii) SN1 / nucleophilic substitution 1

Page 7 Mark Scheme Syllabus Paper Cambridge International AS/A Level – October/November 2016 9701 22 © UCLES 2016 Question Answer Mark 4(c)(i) Sodium / potassium hydroxide Ethanol / alcohol AND heat 1 1 4(c)(ii) elimination 1 4(c)(iii) 1 1 1 Total: 17

Page 8 Mark Scheme Syllabus Paper Cambridge International AS/A Level – October/November 2016 9701 22 © UCLES 2016 Question Answer Mark 5(a)(i) Cl● and ●CH3 1 5(a)(ii) Cl − and +CH3 / CH3 + 1 5(b)(i) Oxidation OR reduction 1 5(b)(ii) Condensation 1 5(b)(iii) Reduction OR oxidation OR addition 1 5(b)(iv) Addition 1 Total: 6