Cambridge A Level Chemistry 9701 — 2016 May/June Paper 2 · Variant 1

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 9701/21 Paper 2 AS Level Structured Questions May/June 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 12 printed pages. [Turn over IB16 06_9701_21/4RP © UCLES 2016 *3721112504*

2 9701/21/M/J/16 © UCLES 2016 Answer all the questions in the spaces provided. 1 (a) Complete the table to show the composition and identity of some atoms and ions. name of element nucleon number atomic number number of protons number of neutrons number of electrons overall charge lithium 6 3 … … … +1 oxygen … … … 9 10 … … 54 26 26 … 24 … … … … 17 18 … 0 [4] (b) Beams of protons, neutrons and electrons behave differently in an electric field due to their differing properties. The diagram shows the path of a beam of electrons in an electric field. Add and label lines to represent the paths of beams of protons and neutrons in the same field. electron beam [3]

3 9701/21/M/J/16 © UCLES 2016 [Turn over (c) The fifth to eighth ionisation energies of three elements in the third period of the Periodic Table are given. The symbols used for reference are not the actual symbols of the elements. ionisation energies, kJ mol–1 fifth sixth seventh eighth X 6274 21 269 25 398 29 855 Y 7012 8496 27 107 31 671 Z 6542 9362 11 018 33 606 (i) State and explain the group number of element Y. group number … explanation … … [1] (ii) State and explain the general trend in first ionisation energies across the third period. … … … [2] (iii) Explain why the first ionisation energy of element Y is less than that of element X. … … … … [2] (iv) Complete the electronic configuration of element Z. 1s2 … [1]

4 9701/21/M/J/16 © UCLES 2016 (d) A sample of strontium exists as a mixture of four isotopes. Information about three of these isotopes is given in the table. mass number 86 87 88 abundance 9.86% 7.00% 82.58% (i) Calculate the abundance of the fourth isotope. abundance = … % [1] (ii) The relative atomic mass of this sample of strontium is 87.71. Calculate the mass number of the fourth isotope. mass number = … [2] [Total: 16]

5 9701/21/M/J/16 © UCLES 2016 [Turn over 2 D, E, F, and G are four consecutive elements in the fourth period of the Periodic Table. (The letters are not the actual symbols of the elements.) D is a soft, silvery metal with a melting point just above room temperature. Its amphoteric oxide, D2O3, has a melting point of 1900 °C and can be formed by heating D in oxygen. G is a solid that can exist as several different allotropes, most of which contain G8 molecules. G burns in air to form GO2 which dissolves in water to form an acidic solution. This solution reacts with sodium hydroxide to form the salt Na2GO3. (a) Suggest the identities of D and G. D … G … [1] (b) Write equations for the reactions of D2O3 with (i) hydrochloric acid, … [2] (ii) sodium hydroxide. … [2] (c) Suggest the type of bonding and structure in D2O3. … [1] (d) Write an equation for the formation of an acidic solution when GO2 dissolves in water. … [1] [Total: 7]

6 9701/21/M/J/16 © UCLES 2016 3 The elements in Group 2, and their compounds, show many similarities and trends in their properties. (a) Magnesium, calcium, strontium and barium all react with cold water. (i) Describe what you would see when some calcium is added to cold water. … … … [3] (ii) Write an equation for the reaction taking place in (i). … [1] (iii) Describe how the reaction of barium with cold water would differ from the reaction of calcium in (i) in terms of what you would see. … … [1] (b) Magnesium oxide can be formed by the reaction of magnesium and oxygen in the air. (i) Draw a fully labelled reaction pathway diagram for the reaction between magnesium and oxygen. energy reaction pathway [2] (ii) Explain why there is no visible reaction when a piece of magnesium ribbon is exposed to the air. … … … [2]

7 9701/21/M/J/16 © UCLES 2016 [Turn over (iii) Magnesium oxide is used to manufacture heat-resistant bricks for furnace linings in the steel-making industry. State and explain the property of magnesium oxide that makes it suitable for this use. … … … … [2] (iv) Suggest a reason why magnesium oxide cannot be used as a lining for any furnaces containing acidic materials. … … [1] (c) The nitrates and carbonates of the Group 2 elements, from magnesium to barium, decompose when heated. (i) State the trend in the temperature of thermal decomposition of these Group 2 nitrates and carbonates. … … [1] (ii) Give the equation for the thermal decomposition of magnesium carbonate. … [1] (iii) Give the equation for the thermal decomposition of calcium nitrate. … [1] [Total: 15]

8 9701/21/M/J/16 © UCLES 2016 4 This question is about molecules with molecular formula C4H8. (a) Give the structures of a pair of positional isomers with the formula C4H8. [1] (b) Give the structures of a pair of chain isomers with the formula C4H8, that do not exhibit stereoisomerism. [1] (c) Give the structures and full names of a pair of stereoisomers with the formula C4H8. … … [2] (d) The structure of a molecule, A, of formula C4H8 is shown. Draw a functional group isomer of molecule A in box B. Explain how molecules A and B could be distinguished by a chemical test. H2C H2C CH2 CH2 A B … … … [3] [Total: 7]

9 9701/21/M/J/16 © UCLES 2016 [Turn over Question 5 starts on the next page.

10 9701/21/M/J/16 © UCLES 2016 5 A reaction sequence is shown. H3C CH2 Br bromoethane H3C CH2 OH ethanol H2C CH2 ethene reaction 4 reaction 5 reaction 1 H3C CH2 CN propanenitrile propanoic acid H3C CH2 C O OH W reaction 3 LiAl H4 reaction 2 (a) Complete the diagram to show the mechanism of reaction 1. Include all necessary charges, partial charges, lone pairs and curly arrows. H3C C H H Br H3C C H H CN + –CN [2] (b) (i) Give the name of the type of reaction involved in reaction 3. … [1] The infra-red spectrum of the propanoic acid produced by reaction 2 is shown. 100 50 0 transmittance 4000 3000 2000 wavenumber / cm–1 1500 1000 500 (ii) Describe and explain the main difference between the infra-red spectrum of W and that of propanoic acid. … … [2]

11 9701/21/M/J/16 © UCLES 2016 [Turn over (c) (i) Reactions 4 and 5 use the same reagent. Give the reagent and conditions needed for reaction 4. reagent … conditions … [2] (ii) Give the conditions needed for reaction 5. … [1] (d) Under appropriate conditions, ethanol and propanoic acid undergo a condensation reaction. (i) State the condition necessary for the reaction. … [1] (ii) Draw the skeletal formula of the organic product of this reaction. [1] (iii) Name the organic product of this reaction. … [1] Question 5 continues over the page.

12 9701/21/M/J/16 © UCLES 2016 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. (e) V reacts with acidified manganate(VII) ions in two different ways depending on the conditions, as shown in the reaction sequence below. propanoic acid H3C CH2 C V T O OH hot, concentrated MnO4 – / H+ cold, dilute MnO4 – / H+ V decolourises bromine water. When the acidified manganate(VII) is hot and concentrated, propanoic acid is the only organic product. When the acidified manganate(VII) is cold and dilute, the organic product is T which has two chiral centres. (i) Give the structural formulae of V and T. V … T … [2] (ii) Identify the types of stereoisomerism shown by V and T. V … T … [2] [Total: 15]

® IGCSE is the registered trademark of Cambridge International Examinations. This document consists of 7 printed pages. © UCLES 2016 [Turn over Cambridge International Examinations Cambridge International Advanced Subsidiary and Advanced Level CHEMISTRY 9701/21 Paper 2 AS Level Structured Questions May/June 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 May/June 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 – May/June 2016 9701 21 © Cambridge International Examinations 2016 Question Mark Scheme Mark Total 1 (a) name of element nucleon no. atomic no. no. of protons no. of neutrons no. of electrons overall charge lithium 6 3 3 3 2 +1 oxygen 17 8 8 9 10 –2 iron 54 26 26 28 24 +2 chlorine 35 17 17 18 17 0 [1] [1] [1] [1] [4] (b) line straight on labelled ‘neutrons’ line (curving) up labelled ‘protons’ proton line clearly shows less (overall) deflection than electron curve [1] [1] [1] [3] (c) (i) Group 16 / 6 / VI AND Big (owtte) increase / big difference / big gap / big jump / jump in increase / jump in difference after 6th IE [1] [1] (ii) increases (across period) due to increasing attraction (of nucleus for electrons) due to increasing nuclear charge / atomic / proton number AND constant/similar shielding / same (outer / number of) shell / energy level [1] [1] [2] (iii) electron (pair) repulsion (Y has a) pair of electrons in a (3)p orbital / a (3)p orbital is full ORA [1] [1] [2] (iv) (1s2)2s22p63s23p5 [1] [1] (d) (i) 0.56(%) [1] [1]

Page 3 Mark Scheme Syllabus Paper Cambridge International AS/A Level – May/June 2016 9701 21 © Cambridge International Examinations 2016 Question Mark Scheme Mark Total (ii) × + × + × + × = ( 0.56) (86 9.86) (87 7.00) (88 82.58) 87.71 100 A A = 84 [1] [1] [2] [16] 2 (a) D = Ga G = Se [1] [1] (b) (i) D2O3 + 6HCl → 2DCl3 + 3H2O M1 = species; M2 = balancing [1] [1] [2] (ii) D2O3 + 2NaOH + 7H2O → 2NaD(OH)4(H2O)2 OR D2O3 + 2NaOH + 3H2O → 2NaD(OH)4 OR D2O3 + 2NaOH → 2NaDO2 + H2O OR D2O3 + 2OH– + 7H2O → 2[D(OH)4(H2O)2]– OR D2O3 + 2OH– + 3H2O → 2[D(OH)4]– OR D2O3 + 2OH– → 2DO2 – + H2O M1 = species; M2 = balancing [1] [1] [2] (c) giant ionic / ionic lattice [1] [1] (d) GO2 + H2O → H2GO3 [1] [1] [7]

Page 4 Mark Scheme Syllabus Paper Cambridge International AS/A Level – May/June 2016 9701 21 © Cambridge International Examinations 2016 Question Mark Scheme Mark Total 3 (a) (i) bubbles / effervescence / fizzing calcium gets smaller / disappears water turns cloudy / milky calcium sinks [1] [1] [1] [1] max [3] (ii) Ca + 2H2O → Ca(OH)2 + H2 [1] [1] (iii) faster bubbling / disappearance of Ba OR no / less precipitate forms (owtte) [1] [1] (b) (i) M1 – general layout with products below reactants AND both labelled M2 – Ea and ∆H / energy change / released labelled with vertical lines [1] [1] [2] (ii) activation energy is high so few/no particles with E ⩾ Ea [1] [1] [2]

Page 5 Mark Scheme Syllabus Paper Cambridge International AS/A Level – May/June 2016 9701 21 © Cambridge International Examinations 2016 Question Mark Scheme Mark Total (iii) high melting / boiling point strong forces (of attraction / between oppositely charged ions) / strong (ionic) bonding [1] [1] [2] (iv) MgO is basic / reacts with acid [1] [1] (c) (i) increases (down the group) [1] [1] (ii) MgCO3 → MgO + CO2 [1] [1] (iii) 2Ca(NO3)2 → 2CaO + 4NO2 + O2 [1] [1] [15] 4 (a) CH2=CHCH2CH3 / CH2CHCH2CH3 AND CH3CH=CHCH3 / CH3CHCHCH3 [1] [1] (b) CH2=CHCH2CH3 / CH2CHCH2CH3 AND (CH3)2C=CH2 / (CH3)2CCH2 [1] [1] (c) trans-but-2-ene (or E) cis-but-2-ene (or Z) [1] [1] [2]

Page 6 Mark Scheme Syllabus Paper Cambridge International AS/A Level – May/June 2016 9701 21 © Cambridge International Examinations 2016 Question Mark Scheme Mark Total (d) B is CH2=CHCH2CH3 OR CH3CH=CHCH3 OR (CH3)2C=CH2 distinguished by addition of bromine brown/red/orange/yellow to colourless/decolourises with B (but not A) [1] [1] [1] [3] [7] 5 (a) M1 = lone pair on C of CN− AND curly arrow from lone pair to C of C—Br M2 = correct dipole on C—Br, curly arrow from C—Br bond to Br AND Br− [1] [1] [2] (b) (i) reduction [1] [1] (ii) disappearance of peak / dip / trough / absorption at 1680–1730 due to (loss of) C=O OR peak at 3200–3650 due to (alcohol) O—H (formation) [1] [1] [1] [1] [2] (c) (i) sodium/potassium hydroxide aqueous [1] [1] [2]

Page 7 Mark Scheme Syllabus Paper Cambridge International AS/A Level – May/June 2016 9701 21 © Cambridge International Examinations 2016 Question Mark Scheme Mark Total (ii) ethanol [1] [1] (d) (i) (conc) H+ / (conc) acid / (conc)H2SO4 / (conc)H3PO4 [1] [1] (ii) [1] [1] (iii) ethyl propanoate [1] [1] (e) (i) V = CH3CH2CHCHCH2CH3 / CH3CH2CH=CHCH2CH3 T = CH3CH2CH(OH)CH(OH)CH2CH3 [1] [1] [2] (ii) V = geometric(al) / cis-trans / E–Z T = optical [1] [1] [2] [15]