Cambridge A Level Chemistry 9701 — 2005 Oct/Nov Paper 2 · Variant 1

This document consists of 10 printed pages and 2 blank pages. SP (MML 8078 3/04) T02630/3 © UCLES 2005 [Turn over UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS General Certificate of Education – Advanced Subsidiary Level and Advanced Level CHEMISTRY Paper 2 Structured Questions AS Core 9701/02 October/November 2005 1 hour 15 minutes Candidates answer on the Question Paper. Additional Materials: Data Booklet READ THESE INSTRUCTIONS FIRST Write your name, Centre number and candidate number in the spaces provided. Write in dark blue or black pen in the spaces provided on the Question Paper. You may use a pencil for any diagrams, graphs, or rough working. Do not use staples, paper clips, highlighters, glue or correction fluid. Answer all questions. The number of marks is given in brackets [ ] at the end of each question or part question. You may lose marks if you do not show your working or if you do not use appropriate units. A Data Booklet is provided. You may use a calculator. DO NOT WRITE IN THE BARCODE. DO NOT WRITE IN THE GREY AREAS BETWEEN THE PAGES. If you have been given a label, look at the details. If any details are incorrect or missing, please fill in your correct details in the spaces provided. Stick your personal label here, if provided. For Examiner’s Use 4 3 2 1 5 TOTAL

Answer all the questions in the space provided. 1 The first six ionisation energies of an element X are given below. (a) Define the term first ionisation energy. … … … … [3] (b) Write an equation, with state symbols, for the second ionisation energy of element X. … [2] (c) Use the data given above to deduce in which Group of the Periodic Table element X is placed. Explain your answer. Group … explanation … … … … [3] The first ionisation energies (I.E.) for the elements of Group IV are given below. (d) Explain the trend shown by these values in terms of the atomic structure of the elements. … … … … … [4] [Total: 12] 2 For Examiner’s Use 9701/02/O/N/05 © UCLES 2005 first second third fourth fifth sixth ionisation energy / kJ mol–1 950 1800 2700 4800 6000 12300 element C Si Ge Sn Pb 1090 786 762 707 716 1st I.E. / kJ mol–1

2 Carbon disulphide, CS2, is a volatile, stinking liquid which is used to manufacture viscose rayon and cellophane. (a) The carbon atom is in the centre of the CS2 molecule. Draw a ‘dot-and-cross’ diagram of the carbon disulphide molecule. Show outer electrons only. [2] (b) Suggest the shape of the molecule and give its bond angle. shape … bond angle … [2] (c) Explain the term standard enthalpy change of formation,
Hf . … … … [3] (d) Calculate the standard enthalpy change of formation of CS2 from the following data. standard enthalpy change of formation of SO2 = –298 kJ mol–1 standard enthalpy change of formation of CO2 = –395 kJ mol–1 standard enthalpy change of combustion of CS2 = –1110 kJ mol–1 [3] 4 For Examiner’s Use 9701/02/O/N/05 © UCLES 2005

(e) Carbon disulphide reacts with nitrogen monoxide, NO, to form a yellow solid and two colourless gases which are produced in a 1:1 molar ratio. Deduce the identity of each gas and write a balanced equation for the reaction. gases … and … equation … [3] [Total: 13] 5 [Turn over For Examiner’s Use 9701/02/O/N/05 © UCLES 2005

3 Nitrogen, which makes up about 80% of the Earth’s atmosphere, is very unreactive. (a) (i) Explain the lack of reactivity of nitrogen. … … … (ii) Nitrogen does, however, undergo some reactions. Write an equation for one reaction of nitrogen, stating the conditions under which it occurs. equation … conditions … … … (iii) Suggest why nitrogen does react in the example you have chosen. … … [6] Ammonium nitrate, NH4NO3, is a commercially important compound of nitrogen. (b) (i) State one large-scale use of ammonium nitrate. … (ii) What are the environmental consequences of the uncontrolled use of ammonium nitrate? … … … … [4] 6 For Examiner’s Use 9701/02/O/N/05 © UCLES 2005

When solid ammonium nitrate is heated with solid sodium hydroxide in a test-tube, three products are formed. A colourless alkaline gas, Y, is given off, and a colourless liquid can be seen on the cooler parts of the test-tube. A white solid remains in the tube. (c) (i) Identify gas Y. … (ii) Write an equation, with state symbols, for the reaction of ammonium nitrate with sodium hydroxide. … [3] (d) In order to produce gas Y in a pure state in the laboratory, it must be passed through a drying agent. Why is concentrated sulphuric acid not suitable for drying gas Y? … … [1] [Total: 14] 7 [Turn over For Examiner’s Use 9701/02/O/N/05 © UCLES 2005

4 Alcohols are widely used as solvents and in the manufacture of esters. Butan-1-ol, C4H10O, is an example of a primary alcohol. (a) What is meant by the term primary alcohol? … [1] (b) There are three more alcohols with molecular formula C4H10O that are structural isomers of butan-1-ol. Complete the table below by drawing displayed formulae of each of these three compounds. For each isomer, state whether it is a primary, secondary, or tertiary alcohol. [6] 8 For Examiner’s Use 9701/02/O/N/05 © UCLES 2005 H H H C C H H C H H C OH H H primary butan-1-ol isomer 2 isomer 3 isomer 4

(c) Butan-1-ol can be oxidised to a carboxylic acid by heating with an acidified solution of potassium dichromate(VI). (i) What colour change would be seen during this reaction? from … to … (ii) State which of the isomers you have drawn in (b) could also be oxidised to form a carboxylic acid. … [3] [Total: 10] 9 [Turn over For Examiner’s Use 9701/02/O/N/05 © UCLES 2005

5 Compound Z, an organic compound with three functional groups, has the molecular formula C4H6O2. The functional groups can be confirmed by the following tests. (a) Test for the first functional group. Z decolourises aqueous bromine. What functional group is shown to be present in Z by this test? … [1] (b) Tests for the second functional group. Z reacts with sodium to give hydrogen and a solid compound of formula C4H5O2Na. When Z is heated with ethanoic acid and a few drops of concentrated sulphuric acid, a sweet smelling liquid of molecular formula C6H8O3 is formed. What functional group is shown to be present in Z by these tests? … [1] (c) Tests for the third functional group. A few drops of Z form a yellow/orange precipitate when added to 2,4-dinitrophenylhydrazine reagent. When a few drops of Z are warmed with Tollens’ reagent, a silver mirror is formed. What functional group is shown to be present in Z by these tests? … [1] (d) Z does not show cis-trans isomerism. Draw the displayed formula of Z. [2] 10 For Examiner’s Use 9701/02/O/N/05 © UCLES 2005

For Examiner’s Use 9701/02/O/N/05 © UCLES 2005 In parts (e) and (f) you may use R– to represent the part of the molecule that does not react. (e) What is the organic compound formed by the reactions of Z in each of the tests in (b)? with sodium with ethanoic acid [2] (f) Draw the structure of the organic compound formed by Z in each of the tests in (c). with Tollens’ reagent with 2,4-dinitrophenylhydrazine, [2] (g) But-2-enoic acid is an isomer of Z which shows cis-trans isomerism. Draw a displayed formula of the cis isomer of this acid. [2] [Total: 11] NHNH2 NO2 NO2 11

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UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS GCE Advanced Level MARK SCHEME for the November 2005 question paper 9701 CHEMISTRY 9701/02 Paper 2 maximum raw mark 60 This mark scheme is published as an aid to teachers and students, to indicate the requirements of the examination. It shows the basis on which Examiners were initially instructed to award marks. It does not indicate the details of the discussions that took place at an Examiners’ meeting before marking began. Any substantial changes to the mark scheme that arose from these discussions will be recorded in the published Report on the Examination. All Examiners are instructed that alternative correct answers and unexpected approaches in candidates’ scripts must be given marks that fairly reflect the relevant knowledge and skills demonstrated. Mark schemes must be read in conjunction with the question papers and the Report on the Examination. The minimum marks in these components needed for various grades were previously published with these mark schemes, but are now instead included in the Report on the Examination for this session. • CIE will not enter into discussion or correspondence in connection with these mark schemes. CIE is publishing the mark schemes for the November 2005 question papers for most IGCSE and GCE Advanced Level and Advanced Subsidiary Level syllabuses and some Ordinary Level syllabuses.

Page 1 Mark Scheme Syllabus Paper GCE A LEVEL – November 2005 9701 2 © University of Cambridge International Examinations 2005 1 (a) Energy required to remove one electron from each atom (1) in one mole of (1) gaseous atoms of an element (1) (‘Energy change when one mole of gaseous atoms loses one mole of electrons’ would score all three marks.) [3] (b) X+(g) → X2+(g) + e- equation (1) state symbols (1) [2] (c) Group 5 (1) sharp rise in successive ionisation energies between 5th and 6th IEs (1) indicating change to a different shell/energy level or outer shell contains 5 electrons (1) [3] (d) down the Group atomic radii increase/ outer electrons are increasingly further away (1) electrons are added to new shells/more shells (1) more shielding (1) despite increase in nuclear charge (1) [4] [Total: 12] 2 (a) sulphur atom has 6 /carbon atom has 4 electrons (1) S=C double bonds (4 electrons) clearly shown (1) [2] (b) linear (1) 180o (1) [2]

Page 2 Mark Scheme Syllabus Paper GCE A LEVEL – November 2005 9701 2 © University of Cambridge International Examinations 2005 (c) the enthalpy change when 1 mol of a compound (1) is formed from its elements in their standard states (1) under standard conditions (may be quoted) (1) [3] (d) C + O2 → CO2 -395 S + O2 → SO2 -298 CS2 + 3O2 → CO2 + 2SO2 -1110 C + 2S → CS2 ∆H = -395 + 2(-298) -(-1110) = +119 kJ mol-1 cycle (1) use of 2 for S/SO2 (1) answer (1) [3] (e) CO2 (1) N2 (1) CS2 + 2NO → CO2 + 2S + N2 (1) completely correct equation gets (3) consequential errors to be decided at co-ordination [3] [Total: 13] 3 (a) (i) N≡N bond is very strong (1) large amount of energy required to break it or Ea is very high (1) (ii) N2 + 3H2 → 2NH3 or N2 + O2 → 2NO or 3Mg + N2 → Mg3N2 (may be others) (1) N2/H2 high pressure, high temperature, catalyst N2/O2 high pressure, high temperature, lightning Mg/N2 high temperature, burning Mg any 2 conditions which correspond to the eqn given (2)

Page 3 Mark Scheme Syllabus Paper GCE A LEVEL – November 2005 9701 2 © University of Cambridge International Examinations 2005 (iii) Ea overcome/ high energy input/ Ea lowered by catalyst (1) [6] (b) (i) fertiliser or explosive (1) (ii) NH4NO3 in rivers causes excessive growth of aquatic plants/algae (1) when plants/algae die O2 is used up (1) fish/aquatic life die (1) ‘eutrophication’ for 2 marks [4] (c) (i) NH3 (1) (ii) NH4NO3(s) + NaOH(s) → NH3(g) + NaNO3(s) + H2O(l) equation (1) state symbols (1) [3] (d) reacts with ammonia (1) [1] [Total: 14] 4 (a) a compound which contains the -CH2OH group (1) [1] (b) given in qu. H H H H     HCCCCH     H H OH H H OH H    HC  C CH    H CH3 H H H H    HC  C COH    H CH3 H primary secondary tertiary primary butan-1-ol isomer 2 isomer 3 isomer 4 each correct structure (3 x 1) each correct label (3 x 1) [6] (c) (i) from orange (1) to green (1) (ii) correct primary alcohol (1) [3] [Total: 10]

Page 4 Mark Scheme Syllabus Paper GCE A LEVEL – November 2005 9701 2 © University of Cambridge International Examinations 2005 5 (a) C=C (1) [1] (b) alcohol (1) (ignore any reference to primary or secondary) [1] (c) aldehyde (1) [1] (d) H  H O H H C = O H OH H H        C = C CC = O or C = C H or C = CCC = O        H H H H H C  OH H H  H fully correct structure is worth 2 (2) CH2 = present in wrong structure gets (1) [2] (e) RONa or R+ ONa- (1) RO2CCH3 (1) [2] (f) RCO2H (1) RCH=NNHC6H3(NO2)2 as the minimum (1) [2] (g) H H C=C H3C CO2H correct acid (1) correctly shown as cis (1) [2] [Total: 11]