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    2010 Chemp 3

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    diegocmako
    CHEM

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    © All Rights Reserved
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    2010 Chemp 3

    Uploaded by

    diegocmako
    24 views12 pages
    CHEM

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    2010chemp3

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    CHEM

    Copyright:

    © All Rights Reserved
    Download as PDF or read online from Scribd
    Download as pdf
    24 views12 pages

    2010 Chemp 3

    Uploaded by

    diegocmako
    CHEM

    Copyright:

    © All Rights Reserved
    Download as PDF or read online from Scribd
    Download as pdf
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    ey BOTSWANA EXAMINATIONS COUNCIL = _ incollaboration with > UNIVERSITY OF CAMBRIDGE LOCAL EXAMINATIONS SYNDICATE Botswana General Certificate of Secondary Education CANDIDATE NAME CENTRE CANDIDATE NUMBER | NUMBER. CHEMISTRY 0570/03 Paper 3 October/November 2010 1 hour 15 minutes Candidates answer on the Question Paper. No Additional Materials are required. READ THESE INSTRUCTIONS FIRST Write your Centre number, candidate number and name in the spaces provided at the top of this page. 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 flu. ‘Answer all questions. Write your answers in the spaces provided on the question paper. ‘Show your working for any calculations. You may use a calculator. ‘The number of marks is given in brackets [ ] at the end of each question or part question. A copy of the Periodic Table is printed on page 12, a For Examiner's Use 1 Total This document consists of 11 printed pages and 1 blank page. De (owire) 1582514 eBEC 2010 [Turn over 1 2 Choose one substance from the list that fits the given description. You may use each substance once, more than once or not at all. methane aluminium oxide icon(IV) oxide diamond calcium oxide lead{(II) iodic ammonia chlorine ethanol (a) (i) ahydrocarbon (ii)_an amphoteric oxide .. (ill) a macromolecular compound (iv) a diatomic molecule (v)_ a compound containing an element with oxidation number of +3 (b) Which two substances react forming slag during the blast furnace process? and 2] (e) Which of the substances dissolves in water to form a solution which turns red litmus paper blue? se Ut] [Total: 8] ‘Ammonia is manufactured from nitrogen and hydrogen by the Haber process. (a) (I) Whatare the sources of nitrogen and hydrogen in the production of ammonia? nitrogen hydrogen .. (2) (ii) State the conditions used in the Haber process for making ammonia. catalyst temperature .... pressure .. Use 3 (b) The equation for the reaction of nitrogen and hydrogen is shown. Na + 3H, == 2NH, AH=? eat a The bond energies are given in the table. @ Gi) (ili) (iv) ) bond bond energy kJ/mol N=N 945 N-H 381 H-H 436 Caloulate the total energy change during the breaking of all the bonds in the reactants. total energy = + kJ/mol [2] Calculate the total energy change during the formation of all the bonds in the product. total energy = — . kJ/mol [2] Calculate AH, the total energy change for the formation of 2 moles of ammonia, NH,. total energy change = ..... .. ku/mol [2] State whether the reaction is exothermic or endothermic. [1] Draw a labelled energy level diagram, including activation energy, for the formation of ammonia from its elements. (4) [otal: 16) if 3 4 The table shows two compounds of chlorine and their melting points. ‘compound melting point / °C XCL 770 YC, 23 (a) Which of the compounds, XClor YCl, is covalent? Give a reason for your answer. (2) (b) The ionic equation shows a redox reaction between chlorine and sodium bromide. CL{g) + 2Br-(aq) > 2Cr-(aq) + Br, (aq) () Why is this a redox reaction? (ii) Describe how the colour of sodium bromide solution changes when chlorine is bubbled through it. from... 12) Total: 5] saris se 5 BLANK PAGE 6 4. The scale formed in kettles contains calcium carbonate. When ethanoic acid is added to the scale a reaction occurs. The equation for the reaction is shown. ee CHJCOOH (0) + CACOg (1 n.) “> --(CHJCOO),Ca (a) Balance the equation and include state symbols. 3) (b) Inn experiment, an excess of 0.1 mol/dm? of ethanoic acid was added to a sample of scale and the volume of carbon dioxide produced was measured at time intervals of 20 seconds. The experiment was done at room temperature and pressure. The results are shown in the table. time/s o [| 2 | 4 | 6 | 8 | 100 | 120 | 140 volume of carbon oO 20 40 | 50 60 75 65 65 dioxide produced / cm® I (i) Plot and draw the graph of volume of carbon dioxide against time on the grid provided below. (4) di) (iil) w) z Circle the point on the graph which is incorrect. ty Caloulate the total number of moles of carbon dioxide produced. (1 mole of gas at Lp. occupies 24dm*.) (2) Calculate the mass of calcium carbonate used in the reaction. 3) On the same axes, sketch the expected graph if excess ethanoic acid of concentration 0.2mol/dm? is added to the same mass of the scale. Label the graph X. (2) Total: 15) canines 5 8 The diagram shows the electrolytic cell for the extraction of aluminium from molten aluminium oxide. solid crust of electrolyte electrode Y electrode x. molten electrolyte tap off of molten aluminium molten aluminium (a) (i) Which element are the electrodes made from? [1] (il) Which electrode must be regularly replaced? Why is replacement necessary? 3] (b) A steady current of 250A was allowed to flow through the cell for 2 hours, The equation shows how aluminium is produced in the cell. AIS* + 3e" > AL (i) Calculate the quantity of electric charge used. (ii) Calculate the number of moles of electrons used. [1 faraday = 965000] moles of electrons [1] Fer banners 9 (ill) Caloulate the mass of aluminium produced. (2 (©) Excess aluminium metal powder reacts with moderately concentrated sulphuric acid to form hydrogen and aluminium sulphate. Describe how crystals of hydrated aluminium sulphate, Al,(SO,)5.12H,O, may be made. [4] [Motal: 13] 10 The structure of a macromolecule Terylene is shown 9 9 9 ° I I ll Il C—Yi} -C —0—{__}-0— C7} -C 0 {—_}—0 (a) (i) Whatis a macromolecule? (i)_Draw the structures of the two monomers of Terylene. (1 (iii) Name the type of linkage in Terylene. < [1] iv) State one use of Terylene. | iscsi [f] (b) A molecule of fat contains the same linkages as a molecule of Terylene. Fat is one of the main constituents of food. (i) Name two other main constituents of food, and (ii) Describe how soap can be prepared from fats. (2) . for uu Examiner's (c) Soap formed from fats can be used to determine the hardness of water. ra (i) Compare the effect of the addition of soap solution to hard water with its addition to distilled water. [2] [Total: 13] ‘Copyright Actrowodgoments: ‘Question 5 [Adapted tom Heinemana Eduestonal Publishers: Cnemity for OCA A by David L2ee, ah Paya 2001) Pormiason t roproauce lems where thi parly owned matoral protected ty copyght ls Incuod has boon eought and cleared whore possiio. Evry resonate efor has bown made by the pusher (BEC) to trace copyright holes, tut any tems requing Clesrance have unwittingly been include, the Oe ne ee 12 C © re 1) eunssoid pue einyessduo} WoO! Je

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