Cambridge A Level Chemistry 9701 — 2016 May/June Paper 3 · Variant 3

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 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. Use of a Data Booklet is unnecessary. Qualitative Analysis Notes are printed on pages 10 and 11. A copy of the Periodic Table is printed on page 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. CHEMISTRY 9701/33 Paper 3 Advanced Practical Skills 1 May/June 2016 2 hours Candidates answer on the Question Paper. Additional Materials: As listed in the Confidential Instructions Cambridge International Examinations Cambridge International Advanced Subsidiary and Advanced Level This document consists of 12 printed pages. [Turn over IB16 06_9701_33/6RP © UCLES 2016 *0004049299* Session Laboratory For Examiner’s Use 1 2 3 Total

2 9701/33/M/J/16 © UCLES 2016 1 You will determine the concentration of a solution of hydrochloric acid by diluting it and then titrating the diluted solution against an alkali. HCl (aq) + NaOH(aq) → NaCl (aq) + H2O(l) FA 1 was made by dissolving 1.06 g of sodium hydroxide, NaOH, in distilled water to make 250 cm3 of solution. FA 2 is hydrochloric acid, HCl. bromophenol blue indicator (a) Method • Pipette 25.0 cm3 of FA 2 into the 250 cm3 volumetric flask. Keep remaining FA 2 for use in Question 2. • Add distilled water to make 250 cm3 of solution and shake the flask thoroughly. Label this solution FA 3. • Fill the burette with FA 3. • Use the second pipette to transfer 25.0 cm3 of FA 1 into a conical flask. • Add about 10 drops of bromophenol blue. • Perform a rough titration and record your burette readings in the space below. The end point is reached when the solution becomes a permanent yellow colour. The rough titre is … cm3. • Carry out as many accurate titrations as you think necessary to obtain consistent results. • Make certain any recorded results show the precision of your practical work. • Record, in a suitable form below, all of your burette readings and the volume of FA 3 added in each accurate titration. [7] (b) From your accurate titration results, obtain a suitable value for the volume of FA 3 to be used in your calculations. Show clearly how you obtained this value. 25.0 cm3 of FA 1 required … cm3 of FA 3. [1] I II III IV V VI VII

3 9701/33/M/J/16 © UCLES 2016 [Turn over (c) Calculations Show your working and appropriate significant figures in the final answer to each step of your calculations. (i) Calculate the concentration, in mol dm–3, of sodium hydroxide in FA 1. Use the data in the Periodic Table on page 12. concentration of NaOH in FA 1 = … mol dm–3 (ii) Calculate the number of moles of sodium hydroxide present in 25.0 cm3 of FA 1. moles of NaOH = … mol (iii) Deduce the number of moles of hydrochloric acid present in the volume of FA 3 you have calculated in (b). moles of HCl = … mol (iv) Calculate the concentration, in mol dm–3, of hydrochloric acid in FA 2. concentration of HCl in FA 2 = … mol dm–3 [5] [Total: 13]

4 9701/33/M/J/16 © UCLES 2016 2 Metal carbonates react with dilute acids to produce carbon dioxide. You will identify the metal, M, in a metal carbonate, M2CO3, by measuring the volume of carbon dioxide produced during the reaction of M2CO3 with excess hydrochloric acid. M2CO3(s) + 2HCl (aq) → 2MCl (aq) + CO2(g) + H2O(l) FA 2 is hydrochloric acid, HCl, as used in Question 1. FA 4 is M2CO3. (a) Method Read all instructions before starting your practical work. The diagrams below may help you in setting up your apparatus. clamp water OR clamp water X X • Fill the tub with water to a depth of about 5 cm. • Fill the 250 cm3 measuring cylinder completely with water. Hold a piece of paper towel firmly over the top, invert the measuring cylinder and place it in the water in the tub. • Remove the paper towel and clamp the inverted measuring cylinder so the open end is in the water just above the base of the tub. • Use the 50 cm3 measuring cylinder to place 50 cm3 of FA 2 into the reaction flask, labelled X. • Check that the bung fits tightly in the neck of flask X, clamp flask X, and place the end of the delivery tube into the inverted 250 cm3 measuring cylinder. • Weigh the container with FA 4 and record the mass in the space below. • Remove the bung from the neck of the flask. Tip all the FA 4 into the acid in the flask and replace the bung immediately. Remove the flask from the clamp and swirl it to mix the contents. • Swirl the flask occasionally until no more gas is evolved. Replace the flask in the clamp. • Reweigh the container and record the mass, and the mass of FA 4 used, in the space below. • When no more gas is collected, measure and record the final volume of gas in the measuring cylinder in the space below. [2]

5 9701/33/M/J/16 © UCLES 2016 [Turn over (b) Calculations Show your working and appropriate significant figures in the final answer to each step of your calculations. (i) Use the volume of gas you collected to calculate the number of moles of gas produced. [Assume that 1 mole of gas occupies 24.0 dm3 under these conditions.] moles of gas = … mol (ii) Use your answer to (i) to deduce the number of moles of M2CO3 used in the reaction. moles of M2CO3 = … mol (iii) Use your answer to (ii) and the mass of FA 4 used to calculate the relative formula mass, Mr, of M2CO3. Mr of M2CO3 = … (iv) Use your answer to (iii) and the Periodic Table on page 12 to identify metal M. Explain your answer. M is … … … [4]

6 9701/33/M/J/16 © UCLES 2016 (c) (i) A 250 cm3 measuring cylinder can be read to ±1 cm3. Calculate the maximum percentage error in your reading of the volume of gas. maximum percentage error = … % (ii) It is likely that the volume of carbon dioxide that you collected was less than the theoretical volume. Give two reasons why this volume is likely to be less than the theoretical volume. In each case, suggest and explain a modification to the practical procedure that could help to reduce the difference in volume. reason … … modification … … … reason … … modification … … … [5] [Total: 11]

7 9701/33/M/J/16 © UCLES 2016 [Turn over 3 Qualitative Analysis 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. If any solution is warmed, a boiling tube MUST be used. Rinse and reuse test-tubes and boiling tubes where possible. Where reagents are selected for use in a test, the name or correct formula of the element or compound must be given. (a) FA 5, FA 6, FA 7 and FA 8 are aqueous solutions of organic compounds. All of FA 5, FA 6, FA 7 and FA 8 contain carbon, hydrogen and oxygen only. Half fill the 250 cm3 beaker with water and heat it to about 80 °C. Turn off the Bunsen burner. This will be used as a water bath. To a 2 cm depth of aqueous silver nitrate in a boiling tube add 2 drops of aqueous sodium hydroxide and then add ammonia dropwise until the brown solid just disappears. This solution is Tollens’ reagent and is needed in a test in (i).

8 9701/33/M/J/16 © UCLES 2016 (i) Carry out the following tests on FA 5, FA 6, FA 7 and FA 8 and record your observations in the table. test observations FA 5 FA 6 FA 7 FA 8 To a 1 cm depth in a test-tube, add a small spatula measure of sodium carbonate. To a few drops in a test-tube, add a 1 cm depth of Tollens’ reagent. Place the tube in the water bath and leave to stand. When you have completed this test rinse all tubes used. To a 1 cm depth in a test-tube, add a few drops of acidified potassium manganate(VII). Place the tube in the water bath and leave to stand. (ii) Using your observations from the table, what functional group is present in both FA 5 and FA 6? … (iii) Using your observations from the table, what functional group is present in both FA 5 and FA 8? … (iv) What type of reaction is occurring in the potassium manganate(VII) test? … (v) Using your observations from the table, what functional group is present in FA 7? …

9 9701/33/M/J/16 © UCLES 2016 [Turn over (vi) Suggest a test that would confirm the presence of the functional group in a pure sample of FA 7. Include the result you would expect the test to give. Do not carry out this test. … … … [9] (b) FA 9 and FA 10 are solids that each contain one anion from those listed in the Qualitative Analysis Notes on page 11. (i) Carry out the following tests on FA 9 and FA 10 and record your observations in the table. test observations FA 9 FA 10 To a spatula measure of solid in a boiling tube, add a 1 cm depth of aqueous sodium hydroxide. Warm, then, add a small piece of aluminium foil. Place a spatula measure of solid in a hard-glass test-tube. Heat gently at first and then more strongly. (ii) Using your observations from the table, which two anions could be present in FA 9 and FA 10? anion … or … (iii) Suggest a test that would allow you to decide which of the anions is present. State what observations you would expect. … … (iv) Carry out this test on FA 9 and FA 10 to decide which anion is present in each. observation for FA 9 … anion in FA 9 is … observation for FA 10 … anion in FA 10 is … [7] [Total: 16]

10 9701/33/M/J/16 © UCLES 2016 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) faint white ppt. is nearly always observed unless 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 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

11 9701/33/M/J/16 © UCLES 2016 2 Reactions of anions ion reaction carbonate, CO3 2– CO2 liberated by dilute acids chloride, Cl –(aq) gives white ppt. with Ag+(aq) (soluble in NH3(aq)) bromide, Br –(aq) gives cream ppt. with Ag+(aq) (partially soluble in NH3(aq)) iodide, I –(aq) gives yellow ppt. with Ag+(aq) (insoluble in NH3(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) (insoluble in excess dilute strong acids) sulfite, SO3 2–(aq) gives white ppt. with Ba2+(aq) (soluble in excess dilute strong acids) 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, Cl 2 bleaches damp litmus paper hydrogen, H2 “pops” with a lighted splint oxygen, O2 relights a glowing splint

12 9701/33/M/J/16 © UCLES 2016 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. Group The Periodic Table of Elements 1 H hydrogen 1.0 2 He helium 4.0 1 2 13 14 15 16 17 18 3 4 5 6 7 8 9 10 11 12 3 Li lithium 6.9 4 Be beryllium 9.0 atomic number atomic symbol Key name relative atomic mass 11 Na sodium 23.0 12 Mg magnesium 24.3 19 K potassium 39.1 20 Ca calcium 40.1 37 Rb rubidium 85.5 38 Sr strontium 87.6 55 Cs caesium 132.9 56 Ba barium 137.3 87 Fr francium – 88 Ra radium – 5 B boron 10.8 13 Al aluminium 27.0 31 Ga gallium 69.7 49 In indium 114.8 81 Tl thallium 204.4 6 C carbon 12.0 14 Si silicon 28.1 32 Ge germanium 72.6 50 Sn tin 118.7 82 Pb lead 207.2 22 Ti titanium 47.9 40 Zr zirconium 91.2 72 Hf hafnium 178.5 104 Rf rutherfordium – 23 V vanadium 50.9 41 Nb niobium 92.9 73 Ta tantalum 180.9 105 Db dubnium – 24 Cr chromium 52.0 42 Mo molybdenum 95.9 74 W tungsten 183.8 106 Sg seaborgium – 25 Mn manganese 54.9 43 Tc technetium – 75 Re rhenium 186.2 107 Bh bohrium – 26 Fe iron 55.8 44 Ru ruthenium 101.1 76 Os osmium 190.2 108 Hs hassium – 27 Co cobalt 58.9 45 Rh rhodium 102.9 77 Ir iridium 192.2 109 Mt meitnerium – 28 Ni nickel 58.7 46 Pd palladium 106.4 78 Pt platinum 195.1 110 Ds darmstadtium – 29 Cu copper 63.5 47 Ag silver 107.9 79 Au gold 197.0 111 Rg roentgenium – 30 Zn zinc 65.4 48 Cd cadmium 112.4 80 Hg mercury 200.6 112 Cn copernicium – 114 Fl flerovium – 116 Lv livermorium – 7 N nitrogen 14.0 15 P phosphorus 31.0 33 As arsenic 74.9 51 Sb antimony 121.8 83 Bi bismuth 209.0 8 O oxygen 16.0 16 S sulfur 32.1 34 Se selenium 79.0 52 Te tellurium 127.6 84 Po polonium – 9 F fluorine 19.0 17 Cl chlorine 35.5 35 Br bromine 79.9 53 I iodine 126.9 85 At astatine – 10 Ne neon 20.2 18 Ar argon 39.9 36 Kr krypton 83.8 54 Xe xenon 131.3 86 Rn radon – 21 Sc scandium 45.0 39 Y yttrium 88.9 57–71 lanthanoids 89–103 actinoids 57 La lanthanum 138.9 89 Ac lanthanoids actinoids actinium – 58 Ce cerium 140.1 90 Th thorium 232.0 59 Pr praseodymium 140.9 91 Pa protactinium 231.0 60 Nd neodymium 144.4 92 U uranium 238.0 61 Pm promethium – 93 Np neptunium – 62 Sm samarium 150.4 94 Pu plutonium – 63 Eu europium 152.0 95 Am americium – 64 Gd gadolinium 157.3 96 Cm curium – 65 Tb terbium 158.9 97 Bk berkelium – 66 Dy dysprosium 162.5 98 Cf californium – 67 Ho holmium 164.9 99 Es einsteinium – 68 Er erbium 167.3 100 Fm fermium – 69 Tm thulium 168.9 101 Md mendelevium – 70 Yb ytterbium 173.1 102 No nobelium – 71 Lu lutetium 175.0 103 Lr lawrencium –

® IGCSE is the registered trademark of Cambridge International Examinations. This document consists of 6 printed pages. © UCLES 2016 [Turn over Cambridge International Examinations Cambridge International Advanced Subsidiary and Advanced Level CHEMISTRY 9701/33 Paper 3 Advanced Practical Skills 1 May/June 2016 MARK SCHEME Maximum Mark: 40 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 33 © Cambridge International Examinations 2016 Question Indicative material Mark Total 1 (a) I Two burette readings and titre value given for the rough titre and initial and final burette readings for two (or more) accurate titrations 1 [7] II Titre values recorded for accurate titrations and Appropriate headings for the accurate titration table and cm3 units. • initial / start burette reading / volume / value • final / end burette reading / volume / value • titre or volume / FA 3 and used / added • unit: / cm3 or (cm3 ) or in cm3 (for each heading) 1 III All accurate burette readings are to the nearest 0.05 cm3. 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) • there is only one accurate titration. 1 IV There are two uncorrected accurate titres within 0.10 cm3 • Do not award this mark if, having performed two titres within 0.10 cm3, a further titration is performed which is more than 0.10 cm3 from the closer of the initial two titres, unless a further titration, within 0.10 cm3 of any other, has also been carried out. • Do not award the mark if any “accurate” burette readings (apart from initial 0 cm3) are given to zero dp. 1 V, VI and VII Examiner rounds any burette readings to the nearest 0.05 cm3, checks subtractions and then select the “best” titres using the hierarchy: • two (or more) accurate identical titres, then • two (or more) accurate titres within 0.05 cm3, then • two (or more) accurate titres within 0.10 cm3, etc. These best titres should be used to calculate the mean titre, expressed to nearest 0.01 cm3. Examiner calculates the difference ( δ) between the mean titres obtained by the candidate and the Supervisor. Accuracy marks are awarded as shown. Award V,VI and VII for δ ⩽ 0.20 (cm3) Award V and VI for 0.20 < δ ⩽ 0.40 (cm3) Award V, only, for 0.40 < δ ⩽ 0.80 (cm3) 3

Page 3 Mark Scheme Syllabus Paper Cambridge International AS/A Level – May/June 2016 9701 33 © Cambridge International Examinations 2016 Question Indicative material Mark Total (b) Candidate must take the average of two (or more) titres that are within a total spread of not more than 0.20 cm3. Working / explanation must be shown or ticks must be put next to the two (or more) accurate readings selected. The mean should be quoted to 2 dp, and be rounded to nearest 0.01 cm3. Two special cases, where the mean need not be to 2 dp: • Allow mean expressed to 3 dp only for 0.025 or 0.075 (e.g. 26.325 cm3) • Allow mean expressed to 1 dp, if all accurate burette readings were given to 1 dp and the mean is exactly correct. (e.g. 26.0 and 26.2 = 26.1 is allowed) (e.g. 26.0 and 26.1 = 26.1 is wrong – should be 26.05) Note: the candidate’s mean will sometimes be marked correct even if it was different from the mean calculated by the Examiner for the purpose of assessing accuracy. 1 [1] (c) (i) (1.06/40) × 4 = 0.106 1 [5] (ii) (iii) Correctly calculates n(NaOH) = 0.106 × (25/1000) = 0.00265 and n(HCl) = 0.00265 1 (iv) concentration FA 3 = 0.00265 × 1000/(b) 1 concentration FA 2 = concentration FA 3 × 10 1 All answers correct to 3 or 4 sf (minimum of 3 parts attempted) 1 Question 1 [13] 2 (a) Table for results with • Unambiguous headings and correctly displayed units • Balance readings recorded to same no of dp • One or two measuring cylinder readings recorded (does not have to include volume collected) • Unit: / g or (g) or in g (for each heading), allow grams / grammes for g) and / cm3 or (cm3 ) or in cm3 (for each heading) • Calculates volume of gas/mass FA 4 to 3 sf. 1 [2] Calculated value within 20% of supervisor value 1 (b) (i) (ii) Correctly calculates • n(gas) = correct vol gas ÷ 24 000 to minimum 2 sf and • same number of moles of M2CO3 1 (iii) Mr = correct mass from (a) ÷ (ii) 1

Page 4 Mark Scheme Syllabus Paper Cambridge International AS/A Level – May/June 2016 9701 33 © Cambridge International Examinations 2016 Question Indicative material Mark Total (iv) Ar = (Mr -60)/2 to minimum 2 sf 1 Group 1 element identified as one with the closest Ar and an explanation e.g as it is the nearest 1 [4] (c) (i) % error = (1 × 100)/vol gas collected (if only volume collected shown in (a)) or (1 × 100)/final reading (when initial reading is zero) or (2 × 100)/vol gas collected (if 2 readings) 1 [5] (ii) Reason: gas dissolves (in water/solution) / reacts with water / water absorbs CO2 1 Modification: use a gas syringe / saturate water with carbon dioxide / use hot water / use less water in tub / use smaller volume of more concentrated acid / use oil (other non-aqueous solvent) instead of water 1 Reason: gas escapes before stopper inserted / stopper not inserted quickly enough. 1 Modification: viable means of keeping solid and acid separate before being added / use larger lumps of solid / use more (excess) of a lower concentration of acid 1 Question 2 [11]

Page 5 Mark Scheme Syllabus Paper Cambridge International AS/A Level – May/June 2016 9701 33 © Cambridge International Examinations 2016 FA 5 is HCO2H; FA 6 is CH3CO2H; FA 7 is C2H5OH; FA 8 is C6H12O6; FA 9 is Zn(NO3)2.6H2O; FA 10 is NaNO3 3 (a) (i) FA 5 FA 6 FA 7 FA 8 Fizz / bubbles / effervescence Fizz / bubbles / effervescence no change no change Gas turns limewater milky / cloudy white / white ppt / chalky Gas turns limewater milky / cloudy white / white ppt / chalky No reaction/no change No reaction/no change Silver / black / dark grey and mirror / solid / ppt No reaction / no change / no silver mirror No reaction / no change / no silver mirror Silver / black / dark grey and mirror / solid / ppt Purple to colourless or solution / MnO4– / manganate (VII) decolourised/ disappeared No reaction or remains / turns purple or pink Purple to colourless or solution / MnO4‒/ manganate(VII) decolourised / disappeared Purple to colourless or solution / MnO4‒ / manganate (VII) decolourised / disappeared 4 [9] (ii) (–)CO2H / carboxylic acid 1 (iii) (–)CHO / aldehyde / alkanal or alkene / C=C 1 (iv) Oxidation of organic compound / reduction of MnO4 − / redox or if alkene in (iii) then electrophilic addition 1 (v) (–)OH / (1° / 2°) alcohol / alkanol / hydroxy or alkene / C=C 1 (vi) Add Na to give effervescence / hydrogen / gas which pops with lighted splint, or Add PCl5 / SOCl2 to give misty fumes / steamy fumes / HCl , or Add carboxylic acid AND (conc) sulfuric acid to produce fruity / sweet smell or if alkene in (v) Br2 decolourised / brown to colourless 1

Page 6 Mark Scheme Syllabus Paper Cambridge International AS/A Level – May/June 2016 9701 33 © Cambridge International Examinations 2016 (b) (i) FA 9 FA 10 NaOH No marking points for observations here Al Effervescence / fizz / bubbles Effervescence / fizz / bubbles Fizz / gas / ammonia turns litmus blue Fizz / gas / ammonia turns litmus blue heat Any 2 from: • Melts / dissolves / becomes liquid • Condensation / steam / water vapour • Brown gas / gas turns litmus red • Gas relights glowing splint • Solid turns yellow Any 1 from: • Bubbles • Gas relights glowing splint • Melts / dissolves and to yellow (liquid / solution) 4 [7] (ii) Nitrate / nitrite 1 (iii) Add named acid and (observe) brown gas for nitrite or Add (acidified) potassium manganate(VII) / KMnO4 and purple to colourless / decolourised for nitrite 1 (iv) No reaction for either so anion in each is nitrate / NO3‒ 1 Question 3 [16]