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A Level Chemistry Past Paper Discussion

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Published in: Chemistry
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Discussing the past paper questions of EdExcel A level Chemistry Completely

Muhammed S / Abu Dhabi

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  1. Please check the examination details below before entering your candidate information Candidate surname Centre Number Other names Candidate Number Pearson Edexcel International Advanced Level Time 1 hour 30 minutes Chemistry — WCHII/OI Paper reference International Advanced Subsidiary/Advanced Level UNIT 1 : Structure, Bonding and Introduction to Organic Chemistry Instructions • Use black ink or ball-point pen. • Fill in the boxes at the top of this page with your name, centre number and candidate number. • Answer all questions. • Answer the questions in the spaces provided - there may be more space than you need. Information • The total mark for this paper is 80. • The marks for each question are shown in brackets - use this as a guide as to how much time to spend on each question. • You will be assessed on your ability to organise and present information, ideas, descriptions and arguments clearly and logically, including your use of grammar, punctuation and spelling. • A Periodic Table is printed on the back cover of this paper. Advice • Read each question carefully before you start to answer it. • Show all your working in calculations and include units where appropriate. • Try to answer every question. • Check your answers if you have time at the end. P71875A 02022 Ltd. Turn over Pearson
  2. SECTION A Answer ALL the questions in this section. You should aim to spend no more than 20 minutes on this section. For each question, select one answer from A to D and put a cross in the boxX. If you change your mind, put a line through the box* and then mark your new answer with a cross X. Which mixture results in a displacement reaction? A B C D iron and copper(ll) sulfate solution lead(ll) nitrate solution and sodium iodide solution dilute hydrochloric acid and sodium hydroxide solution zinc and magnesium sulfate solution x (Total for Question 1 = 1 2 3 Which mixture results in a precipitation reaction? A B C D dilute sulfuric acid and potassium hydroxide solution iron and calcium chloride solution chlorine water and potassium bromide solution silver nitrate solution and potassium bromide solution (Total for Question 2 = 1 An atom of forms a nitride ion, NY . What are the numbers of protons, neutrons and electrons in this ion? c Protons 7 7 7 8 Neutrons Electrons 8 8 8 7 7 4 10 10 (Total for Question 3 = 1 mark) mark) mark) z z o z z Use this space for any rough working. Anything you write in this space will gain no credit. 2 8,' 5 ß\0228
  3. 4 5 What is the total number of orbitals in a sulfur atom which contain at least one electron? (Total for Question 4 = 1 mark) Which structure has the name E-2-bromo-3-chloropent-2-ene? (Total for Question 5 = 1 mark) Use this space for any rough working. Anything you write in this space will gain no credit. Turn over 8,' 5 ß\0328
  4. 6 The partial oxidation of butane in the presence of a catalyst has been investigated as a possible source of hydrogen. + 202(g) + 4CO(g) + 5H2(g) (a) What is the most significant hazard associated with the pollutant CO(g)? A B C D it is a major contributor to the formation of acid rain it strongly absorbs infrared radiation c-Ö2_ it is toxic at low concentrations it is the main cause of ozone layer depletion , (b) A mixture of 40 cm3 of butane and 20cm3 of oxygen reacts in a sealed system to form carbon monoxide and hydrogen. What is the total volume of gas in the system at the end of the reaction, in cm3? A B D (1) 30 60 120 (Total for Question 6 = 2 marks) Use this space for any rough working. Anything you write in this space will gain no credit.
  5. 7 o Octane, C8H18, reacts with bromine in the presence of ultraviolet radiation. (a) What is the role of ultraviolet radiation in the reaction? to break the Br—Br bond only B to break a C—H bond only C to break a C—C bond only D to break both the Br—Br and a C—H bond (b) One of the steps of the reaction is shown. C8H17• + Br2 + C8H17Br + Br• What is the name of this step and the type of bond breaking that takes place in the bromine molecule? (1) (1) A B D Name of step initiation initiation propagation propagation Type of bond breaking heterolytic homolytic heterolytic homolytic (c) What is the overall equation for the reaction of octane with bromine? A B c D C8H18 C8H18 C8H18 C8H18 Br2 Br2 Br2 3Br2 (1) C8H16Br2 + 1-42 C8H17Br + HBr 2C4H9Br 2C r + 4HBr (Total for Question 7 = 3 marks) Use this space for any rough working. Anything you write in this space will gain no credit. 5 Turn over
  6. 8 A stream of liquid from a burette is deflected by a charged rod. burette charged rod beaker Which substance, in its liquid state, will be deflected the most? A B c D csH,a CC14 BC13 CH2C12 (Total for Question 8 = 1 mark) Use this space for any rough working. Anything you write in this space will gain no credit. 8,' 5 ß\0628
  7. 9 A piece of copper is shown. 4 cm 8 cm 1 2 cm How many moles of copper atoms are there in this piece of copper? [Density of copper = 8.96 g cm-3] A B c D 0.675 1.48 .05 54.2 (Total for Question 9 = 1 mark) Use this space for any rough working. Anything you write in this space will gain no credit. Turn over 8,' 5 ß\0728
  8. 10 Mass spectrometers are used in chemical analysis. (a) In which region of this mass spectrometer are the ions accelerated? Q vaporised sample region P region Q region R region S electromagnet to vacuum pump s amplifier chart recorder B C D (b) Four iron ions are present in a stream of ions in a mass spectrometer. The paths of these ions are shown. path 4 stream of Ions path 3 path 1 path 2 Which of these ions will follow path 1 through the mass spectrometer? 54 24 6Fe24 8,' 5 ß\0828 (1) (1) z z o z z 8
  9. (c) Naturally-occurring chlorine has two isotopes, 35Cl and 37Cl. How many peaks due to the singly-charged molecular ions are seen in the mass spectrum of chlorine, C12? (1) (Total for Question 10 = 3 marks) Use this space for any rough working. Anything you write in this space will gain no credit. Turn over
  10. 11 The graph shows the first ionisation energies of some consecutive elements from Periods 2 and 3 of the Periodic Table. The letters used to label the elements are not their chemical symbols. x w First ionisation energy Atomic number (a) Which element has only one p orbital containing a pair of electrons? A B C D element U element V element W element X (b) Which element is the least reactive? A B C D element S element X element Y element Z (c) Which element has the greatest second ionisation energy? (1) (1) (1) z z o z z A B C D 10 element S element T element X element Y (Total for Question 11 = 3 marks) p 7187 01() 28
  11. 12 A mass of 4.08g of hydrated copper(ll) sulfate, CuS04•5H20, was dissolved in deionised water to form 250 cm3 of solution. What is the concentration of the copper(ll) sulfate solution formed, in mol dm-3? o A B c D 0.0163 .0256 0.0654 0.102 (Total for Question 12 = 1 mark) 13 A mass of 2.50g of sodium chloride reacts with excess lead(ll) nitrate solution forming lead(ll) chloride with a yield of 95 %. What is the mass of lead(ll) chloride, PbC12, formed? + 2NaN03 [Mr values: NaCl = 58 5 2NaCl + -+ PbC12 PbC12 = 278.2] A B c D 5.65 g 5.94g 11.3g 11.9g (Total for Question 13 = 1 mark) TOTAL FOR SECTION A = 20 MARKS 11 Turn over p 7187 01
  12. SECTION B Answer ALL the questions. Write your answers in the spaces provided. 14 This question is about barium and barium compounds. (a) The graph shows the first eight ionisation energies of barium. 12000 10000 Ionisation energy / kJ mol-I 6000 4 000 2 000 10 Electron removed 12 (i) Write an equation, including state symbols, for the third ionisation energy of barium. (ii) State how the graph confirms that barium is in Group 2 in the Periodic Table. p 7187 012 28 (1)
  13. (b) An acidified aqueous solution of barium chloride, BaC12, is used to test for sulfate ions. (i) Draw a dot-and-cross diagram for barium chloride. Show the outer electrons only. (2) (ii) Calculate the mass of barium chloride needed to form 150 cm3 of BaC12(aq) with a concentration of 0.200 mol dm- . Give your answer to an appropriate number of significant figures. (2) (iii) The barium chloride solution is acidified to prevent carbonate ions giving a false positive result. Write the ionic equation for the reaction of hydrochloric acid with carbonate ions. State symbols are not required. (1) (c) Give a reason why solid barium chloride does not conduct electricity. (1) (Total for Question 14 = 8 marks) 13 Turn over p 7187 01 328
  14. 15 This question is about hydrocarbons obtained from crude oil. (a) Petrol used in cars has a high proportion of the alkane iso-octane. Iso-octane can be formed by heating octane to 400 oc in the presence of a catalyst. octane (i) Give the IUPAC name for iso-octane. iso-octane (1) 14 (ii) Name the industrial process used to convert octane into iso-octane. (1) (iii) Give a reason why petrol needs a high proportion of iso-octane. (1) p 7187 O I '1 2 8
  15. (b) Another way to produce iso-octane is by reacting iso-butane with 2-methylpropene. iso-butane 2-methylpropene iso-octane Draw the skeletal formulae of four isomers of 2-methylpropene. Include only one isomer that does not decolorise bromine water. p 7187 015 28 (4) 15 Turn over
  16. (c) 2-methylpropene reacts with hydrogen bromide to form two possible products. (i) Draw the mechanism for the formation of the major product of the reaction between 2-methylpropene and hydrogen bromide, HBr. Include curly arrows, and relevant lone pairs and dipoles. (4) major product minor prodcut primary carbocation (ii) Give the reason why your product in (c)(i) is the major product. (d) Another component of petrol, compound X, contains 92.3% carbon and 7.7% hydrogen by mass. (i) Calculate the empirical formula of compound X. You must show all your working. 16 p 7187 016 28 (1) (2)
  17. (ii) A sample of compound X has a mass of 0.267 g and vaporises at 85.0 oc and 104kPa to produce a gaseous sample with a volume of 98.0 cm3. Calculate the molar mass of compound X. You must show all your working. [pv= nRT R = 8.31 Jmol-l (4) (iii) Deduce the molecular formula of compound X, using your answers to (d)(i) and (d)(ii). (1) (Total for Question 15 = 19 marks) 17 Turn over p 718 7 017 28
  18. 16 This question is about the Group 4 element germanium and some of its compounds. germanium consists of five stable isotopes. Explain what is meant by the term isotopes. (b) The mass spectrum of a sample of germanium is shown. 40 30 Percentage 20 abundance 10 20.6 70 71 36.7 27.4 7.6 72 73 74 75 76 77 Calculate the relative atomic mass of this sample of germanium. (c) Give the electronic configuration of a germanium atom. p 7187 018 28 (2) (2) (1) 18
  19. (d) Germane is a compound with the formula GeH4. It can be formed by the reaction shown. NaaGe03 + NaBH4 + H20 + GeH4 + 2NaOH + NaB02 (i) Calculate the atom economy, by mass, for the formation of germane. Use of Ge = 72.6 (2) (ii) Germane can donate a proton to ammonia, forming the ion GeH;. NH3 + GeH4 -+ NH: + Gel-fi Draw a dot-and-cross diagram of the ion GeH;. Show the outer electrons only. (iii) Use your answer to (d)(ii) and electron-pair repulsion theory to predict the name of the shape and bond angle of the ion GeH;. Name of the shape Bond angle p 7187 019 28 (2) (2) 19 Turn over
  20. (iv) Germane is toxic and the maximum permitted concentration is 0.640 mg m-3 in air. Calculate the maximum number of germane molecules permitted in a laboratory with a volume of 231 m3 [Avogadro constant (L) = 6.02 x 1023 mol-I] (4) 20 p 7187 28
  21. o (e) A halide of germanium, GeX4, reacts with water as shown. + 2H20 -i Ge02 Of GeXk s added to excess water. The insoluble Geo was removed by filtration. The solution of hydrogen halide formed was then added to excess magnesium carbonate, forming 335.5 cm3 of carbon dioxide at room temperature and pressure (r.t.p.). MgC03 + 2HX -+ MgX2 + C02 + 1-420 [Molar volume of a gas at r.t.p. = 24 cm3 mol-I] Calculate the number of moles of carbon dioxide formed. 00 Deduce the number of moles of HX formed when GeX4 reacted with the excess water. (iii) Deduce the number of moles of GeX4 that reacted with the excess water. (iv) Calculate the molar mass of GeX4 and hence identify X. (1) (1) (2) (Total for Question 16 = 20 marks 21 Turn over p 7187 021
  22. 17 Limonene is an oil extracted from the skin of citrus fruits such as oranges or lemons. It is found in some cleaning products such as those used to remove chewing gum. Limonene has the structure shown. (a) Deduce the molecular formula of limonene. (2) (b) (i) A few drops of acidified potassium manganate(Vll) solution are mixed with a sample of limonene. State the colour change. From to (ii) Draw the skeletal formula of the structure of the organic product formed when the reaction in (b)(i) is carried out with excess acidified potassium manganate(Vll). (1) (iii) Name the type of reaction that limonene undergoes in (b)(i). (1) 22 p 7187 022 28
  23. (c) On heating, limonene reacts to form two molecules of a smaller hydrocarbon, Q. Q can be polymerised to form R, a polymer used to improve the grip of car tyres. A section of R is shown. CH2 H3C CH2 Section of polymer R Draw the structure of Q. (d) Give two ways in which chemists can help minimise problems caused by the disposal of polymers. discuss biodegradable polmer possibilitites incineration or burning of plastic problem p 7187 023 28 (1) (2) Turn over
  24. (e) Limonene is extracted from orange peel using a solvent. Possible solvents are hexane and liquid carbon dioxide. Liquid carbon dioxide can be obtained by allowing solid carbon dioxide to melt under high pressure. (i) Suggest one advantage and one disadvantage of using liquid carbon dioxide rather than hexane to dissolve the limonene. Assume that the carbon dioxide does not escape into the atmosphere. Advantage Disadvantage (ii) Orange peel contains 1.63 % of limonene by mass. A chewing gum remover contains 30 cm3 of limonene per bottle. Calculate the mass of orange peel, in kg, needed to obtain 30 cm3 of limonene. (2) (3) [Density of limonene = 0.841 gcm 3] 24 z z o z z (Total for Question 17 = 13 marks) TOTAL FOR SECTION B = 60 MARKS TOTAL FOR PAPER = 80 MARKS p 7187 02 42 8
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  28. The Periodic Table of Elements 6.9 lithium 23.0 Na sodium 11 39.1 K 19 85.5 rubidium 37 132.9 caesium 55 [223] francium 87 2 9.0 Be beryllium 4 24.3 Mg 12 40.1 Ca calcium 20 87.6 Sr Strontium 38 137.3 barf um 56 [2261 radium 88 relative atornic mass atomic symbol name atomic (proton) number 45.0 sc scandium 21 88.9 yttrium 39 138.9 anthan um 57 [227] actinium 89 • Lanthanide series • Actinide series 47.9 titanium 22 91 .2 Zr zirconium 40 178.5 Hf hafnium 72 [261] Rf 104 140 cerium 58 232 thorium 90 50.9 vanad ium 23 92.9 niobiun 41 180.9 tantalum 73 [262] Db dubnium 105 141 pr 59 [231] Pa 91 (6) 52.0 Cr chromium 24 95.9 MO 42 183.8 w tungsten 74 [266] Sg 106 144 (7) 54.9 Mn 25 [981 Tc 43 186.2 Re rhenium 75 [264] Bh bohrium 107 [147] Pm 1.0 hydrogen 55.8 iron 26 101.1 ruthenium 44 190.2 osmium 76 [277] hassium 108 150 Sm samarium 62 [242] Pu plutonium 94 (9) 58.9 co cobalt 27 102.9 rhodium 45 192.2 iridium 77 [268] 109 152 Eu europium 63 [2431 Am 95 (10) 58.7 n ickel 28 106.4 palladium 46 Pt platinum 78 110 157 Gd gadolinium 64 [2471 Cm 96 (11) 63.5 cu cop*r 29 107.9 Ag silver 47 Au gold 79 159 Tb terbium 65 [245] 97 (12) 65.4 Zn zinc 30 1 12.4 Cd cadmium 48 Hg mercury 80 3 10.8 B boron 27.0 Al aluminium 13 69.7 Ga gallium 31 114.8 In indium 49 thallium 81 4 (14) 12.0 c carbon 6 28.1 Si silicon 14 .6 Gen germani 32 118.7 Sn tin 50 Pb lead 82 5 (15) 14.0 N nitrogen 7 31.0 p phosphorus 15 74.9 As arsenic 33 121 .8 Sb antimony 51 bisrnuth 83 6 (16) 16.0 O oxygen 8 32.1 s sulfur 16 79.0 Se selenium 34 Te tellurium 52 PO polonium 84 7 (17) 19.0 F fluorine 9 35.5 chlorine 17 79.9 bromine 35 1 iodine 53 At astatine 85 (18) 4.0 hel i um 2 20.2 Ne neon 10 39.9 Ar argon 18 83.8 krypton 36 Rn racm 86 Elements with atomic numbers 112-116 have been reported but not fully authenticated 'Ax:tymiun mm-eth 60 238 u ram um 92 61 [237] neptunium 93 163 Dy dysprosium 66 [251] Cf 165 Ho holmium 67 [254] 167 Er erbium 68 [253] Fm fermium 100 169 Tm thulium 69 [256] Md 101 173 Yb ytterbium 70 [254] No 175 lutetium 71 [257] Lr californium ersteiniun 98 99 nobelium 102 103 v•38V SIHI NI 3118MION 00 SIHI NI ION oa SIHI NI ION oa