Formatting page ...
Cambridge International Examinations Cambridge International General Certificate of Secondary Education *2199140551* 0620/42 CHEMISTRY Paper 4 Theory (Extended) February/March 2018 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 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. The syllabus is approved for use in England, Wales and Northern Ireland as a Cambridge International Level 1/Level 2 Certificate. This document consists of 13 printed pages and 3 blank pages. IB18 03_0620_42/3RP UCLES 2018 [Turn over 2 1 This question is about gases. (a) The following substances are gases at room temperature. letter A B C D E F G H substance SO2 Ar CO Cl 2 NH3 CO2 CH4 C 3H 8 Identify, by letter: (i) a gas which combines with water to form acid rain ....................................................... [1] (ii) two gases which exist as diatomic molecules ............................................................... [2] (iii) a gas which bleaches damp litmus paper ...................................................................... [1] (iv) a gas which is used as an inert atmosphere in lamps ................................................... [1] (v) two gases which are found in clean dry air ................................................................... [2] (vi) two gases which are found in refinery gas. ................................................................... [2] (b) NF3 has covalent bonds. (i) What is a covalent bond? .............................................................................................................................................. ........................................................................................................................................ [2] (ii) Complete the dot-and-cross diagram to show the electron arrangement in a molecule of NF3. Show outer shell electrons only. F N F F [3] UCLES 2018 0620/42/F/M/18 3 (c) Air is a mixture. Nitrogen and oxygen are the two most common gases in air. (i) What is meant by the term mixture? .............................................................................................................................................. ........................................................................................................................................ [1] (ii) State the percentage of oxygen, to the nearest whole number, in clean dry air. ........................................................................................................................................ [1] (iii) Describe the steps in the industrial process which enables nitrogen and oxygen to be separated from clean dry air. Use scientific terms in your answer. .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. ........................................................................................................................................ [3] (iv) Which physical property of nitrogen and oxygen allows them to be separated? ........................................................................................................................................ [1] [Total: 20] UCLES 2018 0620/42/F/M/18 [Turn over 4 2 Sodium chloride is a typical ionic compound. (a) The diagram shows part of a lattice of sodium chloride. (i) Complete the diagram to show the ions present. Use + for Na+ ions and for Cl ions. One ion has been completed for you. + [2] (ii) How many electrons does a chloride ion have? ........................................................................................................................................ [1] (iii) Identify an element which has atoms with the same number of electrons as a sodium ion. ........................................................................................................................................ [1] (b) Electrolysis of concentrated aqueous sodium chloride is an important industrial process. (i) What is meant by the term electrolysis? .............................................................................................................................................. ........................................................................................................................................ [2] (ii) Name the products of the electrolysis of concentrated aqueous sodium chloride. 1 ........................................................................................................................................... 2 ........................................................................................................................................... 3 ........................................................................................................................................... [3] (iii) Write an ionic half-equation for the reaction at the cathode. Include state symbols. UCLES 2018 ........................................................................................................................................ [2] 0620/42/F/M/18 5 (c) Silver chloride can be made by reacting aqueous sodium chloride with aqueous silver nitrate. The other product of the reaction is sodium nitrate. The chemical equation for the reaction is shown. NaCl (aq) + AgNO3(aq) AgCl (s) + NaNO3(aq) A student attempted to make the maximum amount of sodium nitrate crystals. The process involved three steps. step 1 The student added aqueous sodium chloride to aqueous silver nitrate and stirred. Neither reagent was in excess. step 2 The student filtered the mixture. The student then washed the residue and added the washings to the filtrate. step 3 The student obtained sodium nitrate crystals from the filtrate. (i) Describe what the student observed in step 1. ........................................................................................................................................ [1] (ii) Why was the residue washed in step 2? .............................................................................................................................................. ........................................................................................................................................ [1] (iii) Give the names of the two processes which occurred in step 3. 1 ........................................................................................................................................... 2 ........................................................................................................................................... [2] (iv) The student started with 20 cm3 of 0.20 mol / dm3 NaCl (aq). Determine the amount of NaCl (aq) used. amount of NaCl (aq) used = .............................. mol The yield of NaNO3 crystals was 90%. Calculate the mass of NaNO3 crystals made. mass of NaNO3 crystals = .............................. g [4] (v) Write a chemical equation for the action of heat on sodium nitrate crystals. ........................................................................................................................................ [2] [Total: 21] UCLES 2018 0620/42/F/M/18 [Turn over 6 3 Limestone rock is mainly calcium carbonate, CaCO3. (a) The limestone cycle is shown. Each step is numbered. limestone step 1 heat calcium carbonate CaCO3(s) step 2 add limited water limewater Ca(OH)2(aq) ................................... ................................... step 4 add CO2 calcium hydroxide lime slaked lime step 3 add an excess of water calcium hydroxide Ca(OH)2(s) (i) Complete the box to give the chemical name and formula of lime. (ii) Which step involves a physical change? ........................................................................................................................................ [1] (iii) What type of reaction is step 1? ........................................................................................................................................ [1] (iv) Suggest how step 2 could be reversed. [2] ........................................................................................................................................ [1] (v) Write a chemical equation for step 4. ........................................................................................................................................ [1] (vi) Explain why step 4 is a neutralisation reaction. Refer to the substances reacting in your answer. .............................................................................................................................................. ........................................................................................................................................ [2] (b) Dolomite is a similar rock to limestone. Dolomite contains magnesium carbonate, MgCO3. Write a chemical equation for the reaction between magnesium carbonate and dilute nitric acid. ............................................................................................................................................... [2] UCLES 2018 0620/42/F/M/18 7 (c) Forsterite is another rock which contains a magnesium compound. A sample of forsterite has the following composition by mass: Mg, 2.73 g; Si, 1.58 g; O, 3.60 g. Calculate the empirical formula of forsterite. empirical formula = .............................. [2] [Total: 12] UCLES 2018 0620/42/F/M/18 [Turn over 8 4 Ammonia is an important chemical. (a) Ammonia is a base. (i) In chemistry, what is meant by the term base? .............................................................................................................................................. ........................................................................................................................................ [1] (ii) Write a word equation to show ammonia behaving as a base. .............................................................................................................................................. ........................................................................................................................................ [2] (b) Ammonia reacts with chlorine. The chemical equation is shown. 2NH3(g) + 3Cl 2(g) N2(g) + 6HCl (g) (i) Calculate the volume of chlorine, measured at room temperature and pressure, needed to react completely with 0.68 g of ammonia. volume of chlorine = .............................. cm3 [3] UCLES 2018 0620/42/F/M/18 9 (ii) The chemical equation can be represented as shown. 2 H N H + 3 Cl Cl N N + 6 H Cl H Use the bond energies in the table to determine the energy change, H, for the reaction between ammonia and chlorine. bond bond energy in kJ / mol N H 390 Cl Cl 240 N N 945 H Cl 430 energy needed to break bonds .............................. kJ energy released when bonds are formed .............................. kJ energy change, H, for the reaction between ammonia and chlorine .............................. kJ [3] (iii) Is the reaction endothermic or exothermic? Explain your answer. .............................................................................................................................................. ........................................................................................................................................ [1] UCLES 2018 0620/42/F/M/18 [Turn over 10 (c) Ammonia reacts with oxygen at high temperatures in the presence of a suitable catalyst to form nitric oxide, NO. 4NH3(g) + 5O2(g) 4NO(g) + 6H2O(g) (i) Explain how this chemical equation shows ammonia acting as a reducing agent. .............................................................................................................................................. ........................................................................................................................................ [1] (ii) Suggest a suitable catalyst for the reaction from the list of metals. Give a reason for your answer. aluminium calcium platinum potassium sodium suitable catalyst ................................................................................................................... reason .................................................................................................................................. [2] UCLES 2018 [Total: 13] 0620/42/F/M/18 11 5 Alcohols are a family of organic molecules which have the same general formula. (a) What is the name given to any family of organic molecules which have the same general formula and similar chemical properties? ............................................................................................................................................... [1] (b) Give the general formula of alcohols. ............................................................................................................................................... [1] (c) Propan-1-ol can be made from propene. (i) Name the reagent and give the conditions needed to convert propene into propan-1-ol. reagent ................................................................................................................................ conditions ............................................................................................................................ [2] (ii) Write a chemical equation for the complete combustion of propan-1-ol. ........................................................................................................................................ [2] (d) A simple sugar can be represented as shown. H O O H Simple sugars can be polymerised to make more complex carbohydrates. (i) Complete the diagram to show part of a carbohydrate polymer made from the simple sugar shown. [2] (ii) Name the chemical process which occurs when a carbohydrate polymer is broken down into simple sugars. ........................................................................................................................................ [1] (iii) What conditions are needed for this process to occur? UCLES 2018 ........................................................................................................................................ [1] 0620/42/F/M/18 [Turn over 12 (e) Chromatography can be used to identify simple sugars in a mixture. A student analysed a mixture of simple sugars by chromatography. All the simple sugars in the mixture were colourless. (i) What is the name given to the type of substance used to identify the positions of the simple sugars on the chromatogram? ........................................................................................................................................ [1] (ii) The student calculated the Rf value of a spot on the chromatogram. Complete the expression for the Rf value of the spot. Rf = [1] (iii) How could a student identify a simple sugar from its Rf value? .............................................................................................................................................. ........................................................................................................................................ [1] (iv) Sometimes not all the substances in a mixture can be identified from the chromatogram produced. Explain why this may happen. ........................................................................................................................................ [1] [Total: 14] UCLES 2018 0620/42/F/M/18 13 BLANK PAGE UCLES 2018 0620/42/F/M/18 14 BLANK PAGE UCLES 2018 0620/42/F/M/18 15 BLANK PAGE Permission to reproduce items where third-party owned material protected by copyright is included has been sought and cleared where possible. Every reasonable effort has been made by the publisher (UCLES) to trace copyright holders, but if any items requiring clearance have unwittingly been included, the publisher will be pleased to make amends at the earliest possible opportunity. 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. Cambridge International Examinations is part of the Cambridge Assessment Group. Cambridge Assessment is the brand name of University of Cambridge Local Examinations Syndicate (UCLES), which is itself a department of the University of Cambridge. UCLES 2018 0620/42/F/M/18 UCLES 2018 12 V Cr Mn Co 27 Ni 28 Cu 29 Zn 30 Fe 57 71 56 55 0620/42/F/M/18 88 90 89 232 thorium actinium Th Ac 140 cerium 139 lanthanum 59 231 protactinium Pa 91 141 praseodymium Pr 58 Ce Db dubnium Rf 105 181 Ta tantalum 73 93 niobium Nb 41 51 vanadium rutherfordium 104 178 La 57 actinoids 89 103 Hf hafnium 72 91 zirconium Zr 40 48 titanium 238 uranium U 92 144 neodymium 60 Nd Sg seaborgium 106 184 W tungsten 74 96 molybdenum Mo 42 52 chromium neptunium Np 93 promethium 61 Pm Bh bohrium 107 186 Re rhenium 75 technetium Tc 43 55 manganese plutonium Pu 94 150 samarium 62 Sm Hs hassium 108 190 Os osmium 76 101 ruthenium Ru 44 56 iron americium Am 95 152 europium 63 Eu Mt meitnerium 109 192 Ir iridium 77 103 rhodium Rh 45 59 cobalt curium Cm 96 157 gadolinium 64 Gd Ds darmstadtium 110 195 Pt platinum 78 106 palladium Pd 46 59 nickel The volume of one mole of any gas is 24 dm3 at room temperature and pressure (r.t.p.). actinoids lanthanoids Ra radium Fr francium 137 87 133 Ba barium Cs caesium lanthanoids 89 yttrium 88 strontium 85 rubidium Y 39 45 Sr 38 40 Ca Rb 37 39 K scandium berkelium Bk 97 159 terbium 65 Tb Rg roentgenium 111 197 gold Au 79 108 silver Ag 47 64 copper californium Cf 98 163 dysprosium 66 Dy Cn copernicium 112 201 Hg mercury 80 112 cadmium Cd 48 65 zinc calcium Ti 26 potassium Sc 25 31 24 einsteinium Es 99 165 holmium 67 Ho 204 Tl thallium 81 115 indium In 49 70 gallium Ga 27 20 24 19 23 aluminium Al 13 11 boron magnesium 23 1 sodium 22 B C N 7 O 8 VI F 9 VII 2 VIII fermium Fm 100 167 erbium 68 Er Fl flerovium 114 207 lead Pb 82 tin 119 Sn 50 73 germanium Ge 32 28 silicon Si 14 12 carbon mendelevium Md 101 169 thulium 69 Tm 209 Bi bismuth 83 122 antimony Sb 51 75 arsenic As 33 31 phosphorus P 15 14 nitrogen nobelium No 102 173 ytterbium 70 Yb Lv livermorium 116 Po polonium 84 128 tellurium Te 52 79 selenium Se 34 32 sulfur S 16 16 oxygen Lr lawrencium 103 175 lutetium 71 Lu At astatine 85 127 iodine I 53 80 bromine Br 35 35.5 chlorine Cl 17 19 fluorine Rn radon 86 131 xenon 54 Xe 84 krypton 36 Kr 40 argon 18 Ar 20 neon Ne 10 4 helium 6 V hydrogen 5 IV He Mg 21 relative atomic mass name atomic symbol atomic number Key III H 1 Group Na 9 11 7 Be beryllium Li 4 3 lithium II I The Periodic Table of Elements 16
|
