Cambridge IGCSE Chemistry (9-1) 0971 — 2019 May/June Paper 4 · 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. A copy of the Periodic Table is printed on page 16. You may lose marks if you do not show your working or if you do not use appropriate units. 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 0971/42 Paper 4 Theory (Extended) May/June 2019  1 hour 15 minutes Candidates answer on the Question Paper. No Additional Materials are required. Cambridge Assessment International Education Cambridge International General Certificate of Secondary Education (9 –1) This document consists of 13 printed pages and 3 blank pages. [Turn over IB19 06_0971_42/FP © UCLES 2019 *5339226275*

2 0971/42/M/J/19 © UCLES 2019 1 The names of eight substances are given. aluminium oxide calcium oxide ethanol nitrogen iron(III) oxide methane oxygen silicon(IV) oxide Answer the following questions about these substances. Each substance may be used once, more than once or not at all. State which substance is: (a) the main constituent of natural gas … [1] (b) a reactant in respiration … [1] (c) the main constituent of bauxite … [1] (d) a product of photosynthesis … [1] (e) a greenhouse gas … [1] (f) a macromolecular solid. … [1]  [Total: 6]

3 0971/42/M/J/19 © UCLES 2019 [Turn over 2 (a) 22Na 11 , 23Na 11 and 24Na 11 are isotopes of sodium. (i) Describe how these sodium isotopes are the same and how they are different in terms of the total number of protons, neutrons and electrons in each. same … … different … …  [3] (ii) Why do all three isotopes have an overall charge of zero? … … [1] (iii) Why do all three isotopes have the same chemical properties? … … [2] (iv) Why do sodium ions have a charge of +1? … … [1] (b) Carbon is an element which exists in different forms. (i) Name two forms of the element carbon that have giant covalent structures. … and … [1] (ii) Name the oxide of carbon that is a toxic gas. … [1]  [Total: 9]

4 0971/42/M/J/19 © UCLES 2019 3 This question is about phosphorus and compounds of phosphorus. (a) Phosphorus has the formula P4. Some properties of P4 are shown. melting point / °C 45 boiling point / °C 280 electrical conductivity non-conductor solubility in water insoluble (i) Name the type of bonding that exists between the atoms in a P4 molecule. … [1] (ii) Explain, in terms of attractive forces between particles, why P4 has a low melting point. … … [1] (iii) Explain why phosphorus is a non-conductor of electricity. … … [1] (b) Phosphorus, P4, reacts with air to produce phosphorus(V) oxide, P4O10. (i) Write a chemical equation for this reaction. … [2] (ii) What type of chemical reaction is this? … [1] (c) Phosphorus(V) oxide, P4O10, is an acidic oxide. Phosphorus(V) oxide, P4O10, reacts with aqueous sodium hydroxide to form a salt containing the phosphate ion, PO4 3–. Water is the only other product. Write a chemical equation for the reaction between phosphorus(V) oxide and aqueous sodium hydroxide. … [2]

5 0971/42/M/J/19 © UCLES 2019 [Turn over (d) Phosphine has the formula PH3. Complete the dot-and-cross diagram to show the electron arrangement in a molecule of phosphine. Show outer shell electrons only. P H H H  [2] (e) Phosphine, PH3, has a similar chemical structure to ammonia, NH3. Ammonia acts as a base when it reacts with sulfuric acid. (i) What is meant by the term base? … [1] (ii) Write a chemical equation for the reaction between ammonia and sulfuric acid. … [2]  [Total: 13]

6 0971/42/M/J/19 © UCLES 2019 4 Methanol is made industrially by reacting carbon monoxide with hydrogen. The gases react at a temperature of 250 °C and a pressure of 75 atmospheres. CO(g) + 2H2(g) CH3OH(g) The forward reaction is exothermic. (a) Suggest a source of hydrogen for this industrial process. … [1] (b) Complete the table using only the words increases, decreases or no change. effect on the rate of the reverse reaction effect on the equilibrium yield of CH3OH(g) adding a catalyst no change increasing the temperature increases decreasing the pressure  [4] (c) Methanol is a member of the homologous series of alcohols. (i) State two general characteristics of a homologous series. 1 … 2 …  [2] (ii) Draw the structures of two different alcohols, each containing three carbon atoms. Show all of the atoms and all of the bonds. Name these two alcohols. name … name …  [4]

7 0971/42/M/J/19 © UCLES 2019 [Turn over (iii) What term is used to describe compounds with the same molecular formula but different structural formulae? … [1] (d) Alcohols react with carboxylic acids to produce esters. (i) The structure of ester X is shown. C O O H C H H C H H H Name ester X. … [1] (ii) Give the name of the carboxylic acid and the alcohol that react together to produce ester X. carboxylic acid … alcohol …  [2] (iii) Ester Y is different from ester X but also has the formula C3H6O2. Draw the structure of ester Y. Show all of the atoms and all of the bonds. …  [2]  [Total: 17]

8 0971/42/M/J/19 © UCLES 2019 5 Copper(II) sulfate crystals, CuSO4.5H2O, are hydrated. Copper(II) sulfate crystals are made by reacting copper(II) carbonate with dilute sulfuric acid. The equation for the overall process is shown. CuCO3 + H2SO4 + 4H2O CuSO4.5H2O + CO2 step 1 Powdered solid copper(II) carbonate is added to 50.0 cm3 of 0.05 mol / dm3 sulfuric acid until the copper(II) carbonate is in excess. step 2 The excess of copper(II) carbonate is separated from the aqueous copper(II) sulfate. step 3 The aqueous copper(II) sulfate is heated until the solution is saturated. step 4 The solution is allowed to cool and crystallise. step 5 The crystals are removed and dried. (a) Calculate the maximum mass of the copper(II) sulfate crystals, CuSO4.5H2O, that can form using the following steps. ● ● Calculate the number of moles of H2SO4 in 50.0 cm3 of 0.05 mol / dm3 H2SO4.  … mol ● ● Determine the number of moles of CuSO4.5H2O that can form.  … mol ● ● The Mr of CuSO4.5H2O is 250. Calculate the maximum mass of CuSO4.5H2O that can form.  … g  [3]

9 0971/42/M/J/19 © UCLES 2019 [Turn over (b) Steps 1–5 were done correctly but the mass of crystals obtained was less than the maximum mass. Explain why. … [1] (c) State two observations that would indicate that the copper(II) carbonate is in excess in step 1. 1 … 2 …  [2] (d) When the reaction in step 1 is done using lumps of copper(II) carbonate instead of powder, the rate of reaction decreases. All other conditions are kept the same. Give a reason for this. Explain your answer in terms of particles. … … … [2] (e) Name a different substance, other than copper(II) carbonate, that could be added to dilute sulfuric acid to produce copper(II) sulfate in step 1. … [1] (f) Name the process used to separate the aqueous copper(II) sulfate from the excess of copper(II) carbonate in step 2. … [1] (g) The solution of aqueous copper(II) sulfate was heated until it was saturated in step 3. (i) Suggest what is meant by the term saturated solution. … … … [2] (ii) What evidence would show that the solution was saturated in step 3? … [1] (iii) Why should the aqueous copper(II) sulfate not be heated to dryness in step 3? … [1]  [Total: 14]

10 0971/42/M/J/19 © UCLES 2019 6 The halogens are the elements in Group VII of the Periodic Table. (a) Predict the physical state and colour of astatine at room temperature and pressure. physical state … colour …  [2] (b) When chlorine reacts with aqueous potassium bromide a displacement reaction occurs. (i) Describe the colour change of the solution. from … to …  [2] (ii) Write a chemical equation for this reaction. … [2] (c) Reactions occur when some aqueous solutions of halogens are added to aqueous solutions of halides. Use the key to complete the table to show the results of adding halogens to halides. key = reaction = no reaction halides KCl (aq) KBr(aq) KI(aq) halogens Cl 2(aq)  Br2(aq) I2(aq)  [2]  [Total: 8]

11 0971/42/M/J/19 © UCLES 2019 [Turn over 7 (a) Displacement reactions occur between metals and metal ions. Displacement reactions can be used to determine the order of reactivity of metals such as lead (Pb), nickel (Ni), and silver (Ag). The ionic equation for a displacement reaction is shown. Ni(s) + Pb2+(aq) Pb(s) + Ni2+(aq) The ionic half-equations for this reaction are shown. Ni(s) Ni2+(aq) + 2e– Pb2+(aq) + 2e– Pb(s) The ionic half-equations show that electrons are donated by nickel atoms and accepted by lead ions. (i) Identify the reducing agent in the displacement reaction. Give a reason for your answer. reducing agent… reason…  [2] (ii) What is the general term given to the type of reaction in which electrons are transferred from one species to another? … [1] (b) The ionic equation for another displacement reaction is shown. Pb(s) + 2Ag+(aq) 2Ag(s) + Pb2+(aq) Write the two ionic half-equations for this reaction. 1 … 2 …  [2] (c) Use the information in (a) and (b) to put the three metals lead, nickel and silver in order of reactivity. most reactive least reactive  [1]

12 0971/42/M/J/19 © UCLES 2019 (d) Nickel is a transition element. Nickel is stronger than sodium. Describe two other differences in the physical properties of nickel and sodium. 1 … 2 …  [2] (e) Predict one difference in the appearance of aqueous solutions of nickel compounds compared to aqueous solutions of sodium compounds. … … [1] (f) Copper is refined (purified) by electrolysis. Nickel can be refined using a similar method. (i) The diagram shows the refining of nickel by electrolysis. Complete the labels in the boxes. power supply + – cathode made of … electrolyte of … anode made of …  [3] (ii) Indicate, by writing N on the diagram, where nickel is produced. [1]  [Total: 13]

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16 0971/42/M/J/19 © UCLES 2019 Group The Periodic Table of Elements 1 H hydrogen 1 2 He helium 4 I II III IV V VI VII VIII 3 Li lithium 7 4 Be beryllium 9 atomic number atomic symbol Key name relative atomic mass 11 Na sodium 23 12 Mg magnesium 24 19 K potassium 39 20 Ca calcium 40 37 Rb rubidium 85 38 Sr strontium 88 55 Cs caesium 133 56 Ba barium 137 87 Fr francium – 88 Ra radium – 5 B boron 11 13 Al aluminium 27 31 Ga gallium 70 49 In indium 115 81 Tl thallium 204 6 C carbon 12 14 Si silicon 28 32 Ge germanium 73 50 Sn tin 119 82 Pb lead 207 22 Ti titanium 48 40 Zr zirconium 91 72 Hf hafnium 178 104 Rf rutherfordium – 23 V vanadium 51 41 Nb niobium 93 73 Ta tantalum 181 105 Db dubnium – 24 Cr chromium 52 42 Mo molybdenum 96 74 W tungsten 184 106 Sg seaborgium – 25 Mn manganese 55 43 Tc technetium – 75 Re rhenium 186 107 Bh bohrium – 26 Fe iron 56 44 Ru ruthenium 101 76 Os osmium 190 108 Hs hassium – 27 Co cobalt 59 45 Rh rhodium 103 77 Ir iridium 192 109 Mt meitnerium – 28 Ni nickel 59 46 Pd palladium 106 78 Pt platinum 195 110 Ds darmstadtium – 29 Cu copper 64 47 Ag silver 108 79 Au gold 197 111 Rg roentgenium – 30 Zn zinc 65 48 Cd cadmium 112 80 Hg mercury 201 112 Cn copernicium – 114 Fl flerovium – 116 Lv livermorium – 7 N nitrogen 14 15 P phosphorus 31 33 As arsenic 75 51 Sb antimony 122 83 Bi bismuth 209 8 O oxygen 16 16 S sulfur 32 34 Se selenium 79 52 Te tellurium 128 84 Po polonium – 9 F fluorine 19 17 Cl chlorine 35.5 35 Br bromine 80 53 I iodine 127 85 At astatine – 10 Ne neon 20 18 Ar argon 40 36 Kr krypton 84 54 Xe xenon 131 86 Rn radon – 21 Sc scandium 45 39 Y yttrium 89 57–71 lanthanoids 89–103 actinoids 57 La lanthanum 139 89 Ac lanthanoids actinoids The volume of one mole of any gas is 24 dm3 at room temperature and pressure (r.t.p.). actinium – 58 Ce cerium 140 90 Th thorium 232 59 Pr praseodymium 141 91 Pa protactinium 231 60 Nd neodymium 144 92 U uranium 238 61 Pm promethium – 93 Np neptunium – 62 Sm samarium 150 94 Pu plutonium – 63 Eu europium 152 95 Am americium – 64 Gd gadolinium 157 96 Cm curium – 65 Tb terbium 159 97 Bk berkelium – 66 Dy dysprosium 163 98 Cf californium – 67 Ho holmium 165 99 Es einsteinium – 68 Er erbium 167 100 Fm fermium – 69 Tm thulium 169 101 Md mendelevium – 70 Yb ytterbium 173 102 No nobelium – 71 Lu lutetium 175 103 Lr lawrencium –

This document consists of 10 printed pages. © UCLES 2019 [Turn over Cambridge Assessment International Education Cambridge International General Certificate of Secondary Education (9–1) CHEMISTRY (9–1) 0971/42 Paper 4 Theory (Extended) May/June 2019 MARK SCHEME Maximum Mark: 80 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 International will not enter into discussions about these mark schemes. Cambridge International is publishing the mark schemes for the May/June 2019 series for most Cambridge IGCSE™, Cambridge International A and AS Level and Cambridge Pre-U components, and some Cambridge O Level components.

0971/42 Cambridge IGCSE (9–1) – Mark Scheme PUBLISHED May/June 2019 © UCLES 2019 Page 2 of 10 Generic Marking Principles These general marking principles must be applied by all examiners when marking candidate answers. They should be applied alongside the specific content of the mark scheme or generic level descriptors for a question. Each question paper and mark scheme will also comply with these marking principles. GENERIC MARKING PRINCIPLE 1: Marks must be awarded in line with: • the specific content of the mark scheme or the generic level descriptors for the question • the specific skills defined in the mark scheme or in the generic level descriptors for the question • the standard of response required by a candidate as exemplified by the standardisation scripts. GENERIC MARKING PRINCIPLE 2: Marks awarded are always whole marks (not half marks, or other fractions). GENERIC MARKING PRINCIPLE 3: Marks must be awarded positively: • marks are awarded for correct/valid answers, as defined in the mark scheme. However, credit is given for valid answers which go beyond the scope of the syllabus and mark scheme, referring to your Team Leader as appropriate • marks are awarded when candidates clearly demonstrate what they know and can do • marks are not deducted for errors • marks are not deducted for omissions • answers should only be judged on the quality of spelling, punctuation and grammar when these features are specifically assessed by the question as indicated by the mark scheme. The meaning, however, should be unambiguous. GENERIC MARKING PRINCIPLE 4: Rules must be applied consistently e.g. in situations where candidates have not followed instructions or in the application of generic level descriptors.

0971/42 Cambridge IGCSE (9–1) – Mark Scheme PUBLISHED May/June 2019 © UCLES 2019 Page 3 of 10 GENERIC MARKING PRINCIPLE 5: Marks should be awarded using the full range of marks defined in the mark scheme for the question (however; the use of the full mark range may be limited according to the quality of the candidate responses seen). GENERIC MARKING PRINCIPLE 6: Marks awarded are based solely on the requirements as defined in the mark scheme. Marks should not be awarded with grade thresholds or grade descriptors in mind.

0971/42 Cambridge IGCSE (9–1) – Mark Scheme PUBLISHED May/June 2019 © UCLES 2019 Page 4 of 10 Question Answer Marks 1(a) methane 1 1(b) oxygen 1 1(c) aluminium oxide 1 1(d) oxygen 1 1(e) methane 1 1(f) silicon(IV) oxide 1 Question Answer Marks 2(a)(i) M1 protons (are the same) / 11 protons (1) M2 electrons (are the same) / 11 electrons (1) M3 neutrons (are different) / 11,12,13 neutrons (1) 3 2(a)(ii) same number of protons and electrons (1) 1 2(a)(iii) M1 same number of electrons (1) M2 (same number of) electrons in outer shell (1) 2 2(a)(iv) (they all have) 1 more proton than electrons / 11 protons and 10 electrons 1 2(b)(i) diamond / graphite / graphene ANY TWO 1 2(b)(ii) carbon monoxide 1

0971/42 Cambridge IGCSE (9–1) – Mark Scheme PUBLISHED May/June 2019 © UCLES 2019 Page 5 of 10 Question Answer Marks 3(a)(i) covalent 1 3(a)(ii) forces of attraction between molecules AND are weak / need a small amount of energy to break 1 3(a)(iii) no moving or flowing or mobile charged particles or ions or electrons 1 3(b)(i) P4 + 5O2 → P4O10 M1 all formulae correct (1) M2 equation correctly balanced (1) 2 3(b)(ii) redox / combustion 1 3(c) P4O10 + 12NaOH → 4Na3PO4 + 6H2O M1 Na3PO4 (1) M2 equation completely correct (1) 2 3(d) M1 3 pairs of bonding electrons (1) M2 only 1 lone pair on P (1) 2 3(e)(i) proton / H+ / hydrogen ion acceptor 1 3(e)(ii) 2NH3 + H2SO4 → (NH4)2SO4 M1 (NH4)2SO4 (1) M2 equation completely correct (1) 2

0971/42 Cambridge IGCSE (9–1) – Mark Scheme PUBLISHED May/June 2019 © UCLES 2019 Page 6 of 10 Question Answer Marks 4(a) water / natural gas / hydrocarbons 1 4(b) effect on the rate of the reverse reaction effect on the percentage of methanol in the equilibrium mixture M1 increases(1) no change increases M3 decreases(1) M2 decreases(1) M4 decreases(1) 4 4(c)(i) any 2 from: • same or similar chemical properties or reactions (1) • (same) general formula (1) • (consecutive members) differ by CH2 (1) • same functional group (1) • common (allow similar) methods of preparation (1) • physical properties vary in predictable manner / show trends / gradually change OR example of a physical property variation i.e. melting point / boiling point / volatility (1) 2

0971/42 Cambridge IGCSE (9–1) – Mark Scheme PUBLISHED May/June 2019 © UCLES 2019 Page 7 of 10 Question Answer Marks 4(c)(ii) M1 (1) M2 propan-1-ol (1) M3 C H H H C H O H C H H H (1) M4 propan-2-ol (1) 4 4(c)(iii) structural isomers / structural isomerism 1 4(d)(i) ethyl methanoate 1 4(d)(ii) M1 methanoic acid (1) M2 ethanol (1) 2

0971/42 Cambridge IGCSE (9–1) – Mark Scheme PUBLISHED May/June 2019 © UCLES 2019 Page 8 of 10 Question Answer Marks 4(d)(iii) M1 correct displayed ester linkage (1) M2 whole molecule fully correct (1) 2 Question Answer Marks 5(a) M1 0.0025 / 2.5 × 10–3 (moles of H2SO4) (1) M2 0.0025 / 2.5 × 10–3 (moles of CuSO4y5H2O) (1) M3 0.625(g) (1) 3 5(b) some copper(II) sulfate remains in solution / some copper(II) sulfate does not form crystals OR some of the crystals decomposed OR some crystals lost in transfer 1 5(c) M1 no more bubbling / fizzing / effervescence (1) M2 solid or powder stops dissolving (1) 2 5(d) M1 (lumps have) smaller surface area OR powder has larger surface area (1) M2 (lumps have) fewer collisions per unit time / less collision frequency OR powder has more collisions per unit time / more collision frequency 2 5(e) copper(II) oxide or copper(II) hydroxide 1 5(f) filtration 1 5(g)(i) M1 containing the maximum amount of dissolved solute / no more solute can dissolve (1) M2 at any given temperature (1) 2

0971/42 Cambridge IGCSE (9–1) – Mark Scheme PUBLISHED May/June 2019 © UCLES 2019 Page 9 of 10 Question Answer Marks 5(g)(ii) when crystals form on a glass rod withdrawn from solution / on a sample of solution placed on microscope slide etc. 1 5(g)(iii) (heating to dryness) would remove water of crystallisation 1 Question Answer Marks 6(a) M1 solid (1) M2 black (1) 2 6(b)(i) M1 colourless (1) M2 to brown / orange / yellow (1) 2 6(b)(ii) Cl2 +2KBr → 2KCl + Br2 OR Cl2 +2Br– → 2Cl – + Br2 M1 all formulae (1) M2 equation balanced correctly (1) 2 6(c) M1 two ticks for Cl2 / KI, Br2 / KI (1) M2 three crosses for Br2 / KCl, I2 / KCl and I2 / KBr (1) 2

0971/42 Cambridge IGCSE (9–1) – Mark Scheme PUBLISHED May/June 2019 © UCLES 2019 Page 10 of 10 Question Answer Marks 7(a)(i) M1 Ni / Nickel (1) M2 (it) loses or donates electrons (1) 2 7(a)(ii) redox 1 7(b) M1 Pb → Pb2+ + 2e(–) / (1) M2 Ag+ + e(–) → Ag (1) 2 7(c) most reactive nickel / Ni lead / Pb least reactive silver / Ag 1 7(d) nickel has M1 higher density (1) ORA nickel has M2 higher melting point / boiling point (1) ORA 2 7(e) solutions of nickel compounds are coloured ORA 1 7(f)(i) M1 electrolyte aqueous or solution of named nickel salt (1) M2 anode impure nickel (1) M3 cathode pure nickel (1) 3 7(f)(ii) nickel produced at cathode under the liquid surface (1) 1