Cambridge A Level Chemistry 9701 — 2012 May/June Paper 2 · Variant 2

For Examiner’s Use 1 2 3 4 Total 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 a soft pencil for any diagrams, graphs or rough working. Do not use staples, paper clips, highlighters, glue or correction fl uid. DO NOT WRITE IN ANY BARCODES. Answer all questions. 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 Structured Questions AS Core May/June 2012 1 hour 15 minutes Candidates answer on the Question Paper. Additional Materials: Data Booklet UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS General Certifi cate of Education Advanced Subsidiary Level and Advanced Level This document consists of 9 printed pages and 3 blank pages. [Turn over IB12 06_9701_22/3RP © UCLES 2012 *0950926149*

2 9701/22/M/J/12 © UCLES 2012 For Examiner’s Use Answer all the questions in the spaces provided. 1 The elements of the third period of the Periodic Table, sodium to sulfur, all form chlorides by direct combination. (a) (i) Sulfur forms a number of chlorides which are liquid at room temperature. Which other element of the third period forms a chloride which is liquid at room temperature? … (ii) Name one element of the third period which burns in chlorine with a coloured fl ame. … (iii) Aluminium chloride may be produced by passing a stream of chlorine over heated aluminium powder in a long hard-glass tube. State two observations you could make during this reaction. … and … (iv) Write a balanced equation, with state symbols, for this reaction of aluminium with chlorine. … (v) No chloride of argon has ever been produced. Suggest a reason for this. … … [7]

3 9701/22/M/J/12 © UCLES 2012 [Turn over For Examiner’s Use (b) When chlorides of the elements of the third period are added to water, some simply dissolve while others can be seen to react with the water. (i) Complete the table below, stating how the chlorides of Na, Al, and Si behave when mixed with water. In the fi rst column use only the terms ‘dissolve’ or ‘react’. element Does the chloride dissolve or react? approximate pH of the resulting solution Na Al Si (ii) What type of reaction takes place between a chloride and water? … [7] (c) Sulfur forms the compound S4N4 with nitrogen. The structure of S4N4 is shown below. Assume all bonds shown are single bonds. S S S S N N N N a b (i) Determine the number of lone pairs of electrons around a nitrogen atom and a sulfur atom in S4N4. nitrogen atom … sulfur atom … (ii) Which bond angle, a or b, in the S4N4 molecule will be smaller? Explain your answer. … … [2] [Total: 16]

4 9701/22/M/J/12 © UCLES 2012 For Examiner’s Use 2 Alcohols such as methanol, CH3OH, are considered to be possible replacements for fossil fuels because they can be used in car engines. (a) Defi ne, with the aid of an equation which includes state symbols, the standard enthalpy change of combustion, , for methanol at 298 K. equation … defi nition … … … [3] Methanol may be synthesised from carbon monoxide and hydrogen. Relevant values for this reaction are given in the table below. compound CO(g) –283 H2(g) –286 CH3OH(g) –726 (b) Use these values to calculate for the synthesis of methanol, using the following equation. Include a sign in your answer. CO(g) + 2H2(g) → CH3OH(g) = …kJ mol–1 [3]

5 9701/22/M/J/12 © UCLES 2012 [Turn over For Examiner’s Use (c) The operating conditions for this reaction are as follows. pressure 200 atmospheres (2 × 107 Pa) temperature 600 K catalyst oxides of Cr, Cu, and Zn In the spaces below, explain how each of these conditions affects the rate of formation of methanol. pressure … … … temperature … … … catalyst … … … [6] [Total: 12]

6 9701/22/M/J/12 © UCLES 2012 For Examiner’s Use 3 Food additives are substances added to food to preserve the fl avour or to improve its taste and appearance. European Union legislation requires most additives used in foods to be labelled clearly in the list of ingredients, either by name or by an ‘E number’. E296 is malic acid which occurs in unripe fruit. Malic acid has the structural formula HO2CCH2CH(OH)CO2H. (a) Some reactions of malic acid are shown below. In the boxes below, give the structural formulae of organic compounds A to F. HO2CCH2CH(OH)CO2H concentrated H2SO4 C F A B heat with CH3CO2H / H+ heat with CH3OH / H+ cold dilute MnO4 – / H+ steam / H3PO4 D E hot concentrated MnO4 – / H+ [6]

7 9701/22/M/J/12 © UCLES 2012 [Turn over For Examiner’s Use (b) What type of reaction is each of the following conversions? malic acid into C … C into D … C into E … [3] (c) Suggest one major commercial use of compounds such as A or B. … [1] (d) (i) Malic acid is chiral. Draw fully displayed formulae of the two optical isomers of malic acid. Indicate with an asterisk (*) the chiral carbon atom. (ii) Compound C also shows stereoisomerism. Draw the skeletal formulae of each of the stereoisomers of C. Label each isomer. [6] (e) The food additive E330 is another organic compound which occurs naturally in fruit. E330 has the following composition by mass: C, 37.5 %; H, 4.17 %; O, 58.3 %. Calculate the empirical formula of E330. [3] [Total: 19]

8 9701/22/M/J/12 © UCLES 2012 For Examiner’s Use 4 Oxygen-containing organic compounds may contain a number of different functional groups including alcohol, aldehyde, carboxylic acid, ester or ketone functional groups. These functional groups may be identifi ed by their reactions with specifi c reagents. (a) On treating compounds containing each of these functional groups with the reagents below, only fi ve reactions occur. Complete the table by placing a tick () in each box where you believe a reaction will occur. You should place no more than fi ve ticks in the table. reagent alcohol R2CHOH aldehyde RCHO carboxylic acid RCO2H ester RCO2R' ketone RCOR’ NaHCO3 Na Cr2O7 2– / H+ [5] Compound G has the empirical formula CH2O and Mr of 90. An aqueous solution of G is neutral. There is no reaction when G is treated with NaHCO3. When 0.30 g of pure G is reacted with an excess of Na, 80 cm3 of H2, measured at room temperature and pressure, is produced. (b) (i) What functional group do these two reactions show to be present in G? … (ii) Use the data to calculate the amount, in moles, of hydrogen atoms produced from 0.30 g of G. (iii) Hence, show that each molecule of G contains two of the functional groups you have given in (i). [4]

9 9701/22/M/J/12 © UCLES 2012 [Turn over For Examiner’s Use (c) Treatment of G with 2,4-dinitrophenylhydrazine reagent produces an orange solid. When G is warmed with Fehling’s reagent, no reaction occurs. (i) What functional group do these reactions show to be present in G? Draw the displayed formula of this functional group. (ii) Use your answers to (b)(i) and (c)(i) to deduce the structural formula of G. [2] (d) Compound G can be both oxidised and reduced. (i) When G is heated under refl ux with acidifi ed K2Cr2O7, compound H is formed. Give the structural formula of compound H. (ii) When G is reacted with NaBH4 under suitable conditions, compound J is formed. Give the structural formula of compound J. [2] [Total: 13]

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UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS GCE Advanced Subsidiary Level and GCE Advanced Level MARK SCHEME for the May/June 2012 question paper for the guidance of teachers 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 must be read in conjunction with the question papers and the report on the examination. • Cambridge will not enter into discussions or correspondence in connection with these mark schemes. Cambridge is publishing the mark schemes for the May/June 2012 question papers for most IGCSE, GCE Advanced Level and Advanced Subsidiary Level syllabuses and some Ordinary Level syllabuses.

Page 2 Mark Scheme: Teachers’ version Syllabus Paper GCE AS/A LEVEL – May/June 2012 9701 22 © University of Cambridge International Examinations 2012 1 (a) (i) silicon/Si or phosphorus/P (1) (ii) sodium or sulfur name required (1) (iii) white solid formed/white fumes seen chlorine gas decolourised aluminium glows or burns any two (2) (iv) 2Al(s) + 3Cl2(g) → Al2Cl6(s) or 2Al(s) + 3Cl2(g) → 2AlCl3(s) equation (1) state symbols (1) (v) outer shell of electrons is full/has a complete octet or valence shell of electrons is full/has a complete octet or activation energy is too high or ionisation energy is too high (1) [7] (b) (i) element Does the chloride dissolve or react? approximate pH of the resulting solution Na dissolve 7 Al react 1 to 4 Si react 1 to 4 one mark for each correct answer (6 × 1) (ii) hydrolysis (1) [7] (c) (i) around the N atom there is only one lone pair around the S atom there are two lone pairs both (1) (ii) angle (a) or sulfur – no mark for this because two lone pairs repel more than one lone pair or lone pair-lone pair repulsions are stronger than lone pair-bond pair repulsions (1) [2] [Total: 16]

Page 3 Mark Scheme: Teachers’ version Syllabus Paper GCE AS/A LEVEL – May/June 2012 9701 22 © University of Cambridge International Examinations 2012 2 (a) CH3OH(l) + 3/2O2(g) → CO2(g) + 2H2O(l) (1) the enthalpy change/heat change/heat evolved when one mole of CH3OH (1) is completely burned or is burned in an excess of air/oxygen (1) [3] (b) ∆Ho reaction = –283 + 2(–286) – (–726) (1) = –129 kJ mol–1 (1) correct sign (1) [3] (c) pressure increases rate (1) by increasing frequency of collisions or by increasing concentration of reactants (1) temperature increases rate (1) because more molecules have energy >Ea (1) catalyst increases rate (1) by providing an alternative route of lower Ea (1) [6] [Total: 12]

Page 4 Mark Scheme: Teachers’ version Syllabus Paper GCE AS/A LEVEL – May/June 2012 9701 22 © University of Cambridge International Examinations 2012 3 (a) heat with CH3OH/H+ heat with CH3CO2H/H+ concentrated H2SO4 hot concentrated MnO4 –/H+ steam/H3PO4 cold dilute MnO4 –/H+ give one mark for each correct compound (6 × 1) [6] (b) malic acid into C dehydration or elimination (1) C into D oxidation (1) C into E addition or hydration (1) [3] (c) solvents or perfumes or flavourings (1) [1] HO2CCH=CHCO2H C HO2CCO2H D HO2CCH(OH)CH(OH)CO2H F HO2CCH2CH(OH)CO2H E HO2CCH2CH(OH)CO2H CH3O2CCH2CH(OH)CO2CH3 A HO2CCH2CHCO2H  OCOCH3 B

Page 5 Mark Scheme: Teachers’ version Syllabus Paper GCE AS/A LEVEL – May/June 2012 9701 22 © University of Cambridge International Examinations 2012 (d) (i) correct compound (malic acid) shown as a pair of enantiomers in 3D (1) chiral carbon (*) atom correctly identified (1) structure fully displayed (1) (ii) give one for each correct skeletal formula (1 + 1) correct cis (or Z) and trans (or E) labels (1) [6] (e) C : H : O = 12 37.5 : 1 4.17 : 16 58.3 = 3.13 : 4.17 : 3.64 (1) = 1 : 1.33 : 1.16 (1) = 6 : 8 : 7 empirical formula is C6H8O7 (1) [3] [Total: 19]

Page 6 Mark Scheme: Teachers’ version Syllabus Paper GCE AS/A LEVEL – May/June 2012 9701 22 © University of Cambridge International Examinations 2012 4 (a) reagent R2CHOH RCHO RCO2H RCO2R’ RCOR’ NaHCO3
Na

Cr2O7 2–/H+

give one mark for each correct tick (5 × 1) [5] (b) (i) alcohol or ROH not hydroxyl or phenol or –OH (1) (ii) n(H2) = 24000 80 = 3.3 × 10–3 mol (1) n(H atoms) = 2 × 3.3 × 10–3 mol = 6.6 × 10–3 mol (1) (iii) n(G) = 90 0.30 = 3.3 × 10–3 mol n(G) : n(H atoms) = 3.3 × 10–3 : 6.6 × 10–3 = 1 : 2 so each –OH group produces one H atom (1) [4] (c) (i) or or and ‘ketone’ (1) (ii) G is HOCH2COCH2OH as the minimum (1) allow the gem diol CH3COCH(OH)2 [2] (d) (i) H is HO2CCOCO2H as the minimum (1) (ii) J is HOCH2CH(OH)CH2OH as the minimum (1) [2] [Total: 13]