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66136916 kimia-paper-2-f4-akhir-sbp-06

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66136916 kimia-paper-2-f4-akhir-sbp-06

  1. 1. SULIT 4541/2 [Lihat sebelah 4541/2 SULIT Untuk Kegunaan Pemeriksa Bahagian Soalan Markah Penuh Markah Diperoleh 1 11 2 9 3 10 4 10 5 10 A 6 10 7 20 B 8 20 9 20 C 10 20 Jumlah Nama : ……………………………………………... Kelas : …...…… SEKTOR SEKOLAH BERASRAMA PENUH KEMENTERIAN PELAJARAN MALAYSIA _______________________________________________ PEPERIKSAAN AKHIR TAHUN TINGKATAN 4 2006 KIMIA KERTAS 2 Dua jam Tiga Puluh Minit JANGAN BUKA KERTAS SOALAN INI SEHINGGA DIBERITAHU 1. Tuliskan nama dan tingkatan pada ruang yang disediakan. 2. Calon dikehendaki membaca maklumat di halaman 2. Kertas soalan ini mengandungi 24 halaman bercetak 4541/2 Kimia Kertas 2 Nov 2006 2½ Jam
  2. 2. SULIT 4541/2 4541/2 SULIT 2 INFORMATION FOR CANDIDATES 1. This question paper consists of three sections: Section A, Section B and Section C. 2. Answer all questions in Section A. Write your answers for Section A in the spaces provided in the question paper. 3. Answer one question from Section B and one question from Section C. Write your answers for Section B and Sectioin C on the lined pages at the end of the question paper. Answer questions in Section B and Section C in detail. You may use questions, diagrams, tables, graphs and other suitable methods to explain your answer. 4. Show your working. It may help you to get marks. 5. If you wish to cancel any answer, neatly cross out the answer. 6. The diagrams in the question are not drawn to scale unless stated. 7. Marks allocated for each question or part question are shown in brackets. 8. The time suggested to answer Section A is 90 minutes, Section B is 30 minutes and Section C is 30 minutes. 9. You may use a non-programmable scientific calculator. 10. Hand in this question paper at the end of the examination.
  3. 3. SULIT 4541/2 [Lihat sebelah 4541/2 SULIT 3 Section A [60 marks] Answer all questions in this section. The time suggested to complete Section A is 90 minutes. 1 Figure 1 shows part of the Periodic Table of the Elements. A, B, C, D, E, F, G and H do not represent the actual symbol of the elements. A F B D E G C H FIGURE 1 Using the letters in the Periodic Table of the Elements in Figure 1, answer the following questions. (a) Choose two elements which are metals and are placed in the same group. …………………………………………………………………………………. [1 mark] (b) Write the electron arrangement for an atom of element F. …………………………………………………………………………………. [1 mark] (c) Write the formula for the ion formed from an atom of element D. …………………………………………………………………………………. [1 mark] (d) (i) State an element which has a special characteristic that is can form coloured compound. …………………………………………………………………………… [1 mark] (ii) State another special characteristic for the element that is stated in (d)(i). …………………………………………………………………………… [1 mark] (e) State one element that forms acidic oxide. …………………………………………………………………………………. [1 mark]
  4. 4. SULIT 4541/2 4541/2 SULIT 4 (f) Arrange A, B, D, E, F and G according to the increase in size of the atoms. …………………………………………………………………………………. [1 mark] (g) Element A can react with water. (i) Write the chemical equation for the reaction between A and water. ……………………………………………………………………………… [1 mark] (ii) When a red litmus paper is put into the solution in (g)(i), the red litmus paper turns blue. Based on the observation, state the property of the solution formed. ……………………………………………………………………………… [1 mark] (h) Element H is less reactive than element E. Explain why. …………………………………………………………………………………... …………………………………………………………………………………... …………………………………………………………………………………... …………………………………………………………………………………... …………………………………………………………………………………... [2 marks]
  5. 5. SULIT 4541/2 [Lihat sebelah 4541/2 SULIT 5 2 Figure 2 shows the structural formula of compound X. FIGURE 2 (a) What is the meaning of molecular formula? …..……………………………………………………………………………. …………………………………………………………………………………. [1 mark] (b) Write the molecular formula of compound X. …………………………………………………………………………………. [1 mark] (c) Can compound X conduct electricity? State a reason for your answer. …………………………………………………………………………………. …………………………………………………………………………………. [2 marks] C C C C C O H OH CH2OH H H H OH OH H OH
  6. 6. SULIT 4541/2 4541/2 SULIT 6 (d) Compound Y contains 52.2% of carbon, 13.0% of hydrogen and 34.8% of oxygen by mass. Given that the relative atomic mass of H=1, C=12, O=16. (i) Find the empirical formula of compound Y. [3 marks] (ii) If the molar mass of compound Y is 46 gmol-1 , find its molecular formula. [2 marks]
  7. 7. SULIT 4541/2 [Lihat sebelah 4541/2 SULIT 7 3 (a) Figure 3 shows the flow chart for the industrial manufacture of sulphuric acid. FIGURE 3 Based on Figure 3, answer the following questions. (i) Name the process of manufacturing sulphuric acid. ……………………………………………………………………………………. [1 mark] (ii) Describe how sulphur dioxide gas can be produced at stage I . ……………………………………………………………………………………. [1 mark] (iii) Name catalyst X in stage II. …………………………………………………………………………………. [1 mark] (iv) Write the chemical equation for the reaction that takes place at stage II. …………………………………………………………………………………. [1 mark] (v) At stage III, sulphur trioxide is dissolved in concentrated sulphuric acid to produce oleum. Write the chemical formula of oleum. …………………………………………………………………………………… [1 mark]
  8. 8. SULIT 4541/2 4541/2 SULIT 8 (b) Brass is an example of alloy. (i) Name the main element which is added to copper to form brass. .…………………………………………………………………………………… [1 mark] (ii) Draw the arrangement of atoms in pure copper and brass. Pure copper Brass [2 marks] (iii) Brass is harder than copper. Explain why. …………………………………………………………………………………... …………………………………………………………………………………... …………………………………………………………………………………... …………………………………………………………………………………... …………………………………………………………………………………... [2 marks ]
  9. 9. SULIT 4541/2 [Lihat sebelah 4541/2 SULIT 9 4 An activity is carried out in the laboratory to determine the end point of the reaction between 25.0 cm3 of potassium hydroxide solution and 1.0 moldm-3 of sulphuric acid. Phenolphthalein is used in the titration to detect the end point of the reaction. Figure 4 shows the set-up of apparatus for the titration. FIGURE 4 The volume of sulphuric acid added and the changes of the colour of potassium hydroxide solution are shown in the Table 4 below. TABLE 4 (a) Name the chemical reaction between potassium hydroxide solution and sulphuric acid. ……………………………………………………………………………… [1 mark] (b) Write a chemical equation for the reaction. ……………………………………………………………………………... [1 mark] Volume of sulphuric acid (cm3 ) 4.50 4.60 4.70 4.80 4.90 5.00 5.10 5.20 5.30 5.40 Colour of potassium hydroxide solution Pink Pink Pink Pink Pink Colour- less Colour- less Colour- less Colour- less Colour- less Sulphuric acid 1.0 moldm-3 25.0 cm3 of potassium hydroxide solution and a few drops of phenolphthalein White tile
  10. 10. SULIT 4541/2 4541/2 SULIT 10 (c) Write the formula of ions which are present in the conical flask when the volume of sulphuric acid added is: (i) 4.50 cm3 ……………………………………………………………………………… (ii) 5.30 cm3 ……………………………………………………………………………… [2 marks] (d) How much sulphuric acid is required to neutralise 25.0 cm3 of potassium hydroxide solution? …………………………………………………………………………….......... [1 mark] (e) Calculate the molarity of potassium hydroxide used in the above activity. [3 marks] (f) If sulphuric acid is replaced with nitric acid with the same molarity, predict the volume of nitric acid require to neutralise 25.0 cm3 of the potassium hydroxide solution. Explain why. …………………………………………………………………………….......... …………………………………………………………………………….......... …………………………………………………………………………….......... [2 mark]
  11. 11. SULIT 4541/2 [Lihat sebelah 4541/2 SULIT 11 5 Figure 5 shows the set-up of apparatus to investigate the electrolysis of 0.0001 moldm-3 sodium chloride solution. FIGURE 5 (a) Name all the anions present in the solution. ……………………………………………………………………………………… [1 mark] (b) What is the energy change that occurs in the electrolysis process? ……………………………………………………………………………………… [1 mark] (c) (i) Name the gas collected in the test tube at electrode X. ……………………………………………………………………………………… [1 mark ] (ii) Write the half equation for the reaction at electrode X. ……………………………………………………………………………………… [1 mark] (iii) Explain how to confirm the gas produced at electrode X. ……………………………………………………………………………………… ……………………………………………………………………………………… ……………………………………………………………………………………… [2 marks] Dilute sodium chloride solution 0.0001 moldm-3 sodium chloride solution Carbon electrode Y Carbon electrode X
  12. 12. SULIT 4541/2 4541/2 SULIT 12 (d) What ion is discharged at electrode Y? Explain your answer. .……………………………………………………………………………………... .……………………………………………………………………………………... ……………………………………………………………………………………… [2 marks ] (e) The volume of gas collected at electrode Y is 30 cm3 . Given that Avogadro number is 6.02  1023 mol-1 and 1 mol of gas occupies a volume of 24 dm3 mol-1 at room condition. (i) Calculate the number of mole of the gas produced. [1 mark] (ii) What is the number of gas molecules collected? [1 mark]
  13. 13. SULIT 4541/2 [Lihat sebelah 4541/2 SULIT 13 6 Figure 6 shows four test tubes contain dry glacial ethanoic acid, aqueous solution of ethanoic acid, dilute hydrochloric acid and aqueous solution of X. P Q R S FIGURE 6 (a) (i) State the colour change of the litmus paper in test tubes Q and R. ................................................................................................................................ [1 mark] (ii) Write the formula of ion which caused the colour change of the litmus paper. ................................................................................................................................ [1 mark] (b) Is there any changes of colour of the litmus paper in test tube P? Explain why. ..................................................................................................................................... ..................................................................................................................................... [2 marks] (c) Table 6 shows the pH value of aqueous solution of ethanoic acid and dilute hydrochloric acid of the same molarity. Type of acid aqueous solution of ethanoic acid dilute hydrochloric acid Molarity 0.1 moldm-3 0.1 moldm-3 pH value 1.0 2.9 TABLE 6 Explain why the pH value of aqueous solution of ethanoic acid is higher than the pH value of dilute hydrochloric acid. .................................................................................................................................... .................................................................................................................................... .................................................................................................................................... [2 marks] Aqueous solution of X Blue litmus paper Dilute hydrochloric acid 0.1 moldm-3 Blue litmus paper Dry glacial ethanoic acid Blue litmus paper Aqueous solution of ethanoic acid 0.1 moldm-3
  14. 14. SULIT 4541/2 4541/2 SULIT 14 (d) Calcium carbonate powder is added into test tube R. Write the chemical equation for the reaction that takes place. .................................................................................................................................... [1 mark] (e) Aqueous solution of X is an acidic solution. As a chemistry student, describe briefly how you are able to prove that X is an acidic solution. You are not allow to use litmus paper, pH meter or any indicators. Procedure: .................................................................................................................................... .................................................................................................................................... .................................................................................................................................... .................................................................................................................................... .................................................................................................................................... .................................................................................................................................... [2 marks] Observation: .................................................................................................................................... .................................................................................................................................... [1 mark]
  15. 15. SULIT 4541/2 [Lihat sebelah 4541/2 SULIT 15 Section B [20 marks] Answer any one question. The time suggested to answer this section is 30 minutes. 7 (a) What is meant by “melting point”? During the melting of naphthalene, the temperature remains constant even though heat is applied. Explain why. [4 marks] (b) Describe the change of the kinetic energy, arrangement and the forces of attraction between the particles at the following states:  before condensation  during condensation  after condensation [10 marks] (c) Figure 7 shows the electron arrangement of ion Y3+ . FIGURE 7 (i) Calculate the nucleon number of atom Y. [2 marks] (ii) Y reacts with oxygen to form oxide Y, with the formula Y2O3. The chemical equation for reaction Y with oxygen is show as: 4Y + 3O2  2Y2O3. Given that the relative atomic mass of Y = 27 and O = 16. Calculate the mass of oxide Y, Y2O3 formed when 10.8 g Y is completely burnt in oxygen. [4 marks] Condensation is the process where a gas changes to its liquid state at a certain temperature and pressure when it is cooled. 14 n e e e e e e e e e e 3+ n  neutron e  electron
  16. 16. SULIT 4541/2 4541/2 SULIT 16 8 (a) Helium, He4 2 exists as a monoatomic gas whereas chlorine, Cl35 17 exists as a diatomic gas. Explain why. [4 marks] (b) Table 8.1 shows the proton number of magnesium, chlorine and carbon. TABLE 8.1 (i) Carbon reacts with chlorine to form a compound. What type of compound formed? Draw the electron arrangement to show the chemical bond in the compound. [3 marks] (ii) Describe how ionic bond is formed between magnesium and chlorine atoms. [7 marks] (c) Figure 8 shows the set-up of apparatus to investigate the electrical conductivity of solid and solution of sodium chloride, NaCl. FIGURE 8 Table 8.2 shows the result of the two experiments. TABLE 8.2 (i) Compare the electrical conductivity of solid and solution of sodium chloride, NaCl. Explain why the results of Experiment I and II are different. [4 marks] (ii) Calculate the mass of sodium chloride, NaCl in 50 cm3 of 0.2 moldm-3 sodium chloride solution. Given that the molar mass of NaCl = 58.5 gmol1 [2 marks] Element Magnesium Chlorine Carbon Proton number 12 17 6 Experiment I II Compound Sodium chloride Sodium chloride State of compound Solid Aqueous Observation Bulb does not light up Bulb lights up Bulb Electrode carbon Sodium chloride Electrode carbon
  17. 17. SULIT 4541/2 [Lihat sebelah 4541/2 SULIT 17 Section C [20 marks] Answer any one question. The time suggested to answer this section is 30 minutes. 9 (a) Reactive metal can be extracted from its ore by electrolysis. Aluminium is a reactive metal. State how aluminium can be extracted from its ore, which contains aluminium oxide. [4 marks] (b) Daniell cell is an example of a voltaic cell. In this cell, zinc and copper are used as electrodes. Explain how a Daniell cell can produce electric current. Use a labelled diagram to explain your answer. [6 marks] (c) A student intends to electroplate an iron spoon with a suitable metal. Design a laboratory experiment to electroplate the iron spoon. Your answer should consist of the following:  Chemicals required  Procedure of the experiment  Diagram showing the set-up apparatus  Half equations involved in the reaction  Observations [10 marks]
  18. 18. SULIT 4541/2 4541/2 SULIT 18 Cation Anion test 10 (a) An insoluble salt can be prepared by the precipitation reaction. Give an example of an insoluble salt and suggest two solutions to prepare the insoluble salt. Write the ionic equation to represent the precipitation reaction. [4 marks] (b) Figure 10 shows an incomplete flow chart of cation and anion tests for salt X. FIGURE 10 Use the reagents listed below to confirm that salt solution of X contains Zn2+ ions and SO4 2- ions. [6 marks] (c) Copper(II) sulphate is a soluble salt. Describe how to prepare a dry sample of copper(II) sulphate in the laboratory. Your answer should consist of the following:  Chemicals required  Procedure of the preparation  Chemical equation involved in the reaction [10 marks] END OF QUESTION PAPER SO4 2- Zn2+ REAGENTS  Sodium hydroxide solution  Ammonia solution  Hydrochloric acid  Barium chloride solution Salt solution of X
  19. 19. SULIT 4541/2 [Lihat sebelah 4541/2 SULIT 19 SPACE FOR YOUR ANSWER Section: …………………………………… Question No.: …………………………. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. …………………………………………………………………………………………………..
  20. 20. SULIT 4541/2 4541/2 SULIT 20 SPACE FOR YOUR ANSWER Section: …………………………………… Question No.: …………………………. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. …………………………………………………………………………………………………..
  21. 21. SULIT 4541/2 [Lihat sebelah 4541/2 SULIT 21 SPACE FOR YOUR ANSWER Section: …………………………………… Question No.: …………………………. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. …………………………………………………………………………………………………..
  22. 22. SULIT 4541/2 4541/2 SULIT 22 SPACE FOR YOUR ANSWER Section: …………………………………… Question No.: …………………………. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. …………………………………………………………………………………………………..
  23. 23. SULIT 4541/2 [Lihat sebelah 4541/2 SULIT 23 SPACE FOR YOUR ANSWER Section: …………………………………… Question No.: …………………………. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. …………………………………………………………………………………………………..
  24. 24. SULIT 4541/2 4541/2 SULIT 24 SPACE FOR YOUR ANSWER Section: …………………………………… Question No.: …………………………. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. …………………………………………………………………………………………………..
  25. 25. 1 BAHAGIAN SEKOLAH KEMENTERIAN PELAJARAN MALAYSIA CHEMISTRY FORM 4 FINAL EXAM 2006 MARKING SCHEME PAPER 2
  26. 26. 2 Marking Scheme Paper 2 Section A Question Number Explanation Mark  1(a) A,B 1 (b) 2.8 1 (c) D3+ 1 (d)(i) C 1 (ii) Form complex ions // Act as catalysts // Exhibit different oxidation numbers 1 (e) E // H 1 (f) F, A, G, E, D, B 1 (g)(i) 2A + 2H2O  2AOH + H2 1 (ii) alkaline 1 (h) 1. Atom E has a smaller size 2. The attraction forces between nucleus and electrons are stronger OR 1. Atom H has a bigger size 2. The attraction forces between nucleus and electrons are weaker. 1 1 2 1 1 Total 11
  27. 27. 3 Question Number Explanation Mark  2 (a) Formula that gives the actual number of atoms of each element that are present in one molecule of the compound 1 (b) C6H12O6 1 (c) 1. No 2. Exits as molecules 1 1 2 (d) (i) C H O 1. Mole 52.2/ 12 13.0 /1 34.8/16 4.35 13.0 2.175 2. Ratio 2 6 1 3. Empirical formula = C2H6O 1 1 1 3 (ii) [2(12) + 6(1) + (16)]n = 46 n = 1 Molecular formula = C2H6O 1 1 2 Total 9 Question Number Explanation Mark  3(a)(i) Contact Process 1 (ii) Sulphur react with oxygen 1 (iii) Vanadium (V) oxide 1 (iv) 2 SO2 + O2  2SO3 1 (v) H2S2O7 1 (b)(i) Tin 1 (ii) 1 1 2 (iii) 1. Tin atoms with different size disturb the orderly arrangement of copper atoms. 2. Tin atoms prevent the layer of copper atoms from sliding. 1 1 2 Total 10 Tin atom Copper atomsPure copper Brass
  28. 28. 4 Question Number Explanation Mark  4(a) Neutralization 1 (b) H2SO4 + 2KOH  K2SO4 + H2O 1 (c)(i) K+ , OH- , SO4 2- 1 (ii) K+ , SO4 2- , H+ 1 (d) 5.0 cm3 1 (e) 1. MaVa = a MbVb b 2. 1.0 (5.0) = 1 Mb (25) 2 3. Mb = 2(1.0)(5.0) = 0.4 mol dm-3 25 1 1 1 3 (f) 1. 10.0 cm3 2. nitric acid is monoprotic acid / sulphuric acid is diprotic acid 1 1 2 Total 10 Question Number Explanation Mark  5(a) Chloride, hydroxide 1 (b) Electrical energy to chemical energy 1 (c)(i) Hydrogen 1 (ii) 2H+ + 2e  H2 1 (iii) 1. Lower a lighted wooden splinter 2. A “pop” sound is heard 1 1 2 (d) 1. Hydroxide ions // OH- 2. The concentration of hydroxide ions is higher 1 1 2 (e)(i) 30 / 0.03 / 0.00125 24000 24 1 (ii) 0.00125 x 6.02 x 1023 / 7.525 x 1020 1 Total 10
  29. 29. 5 Question Number Explanation Mark  6(a) (i) Blue to red 1 (ii) H+ 1 (b) 1. No 2. No water / H+ ions 1 1 2 (c) 1. Ethanoic acid is weak acid, hydrochloric acid is strong acid 2. The concentration of H+ ions in ethanoic acid is lower / The concentration of H+ ions in hydrochloric acid is higher. 1 1 2 (d) CaCO3 + 2HCl  CaCl2 + CO2 + H2O 1 (e) 1. [ Material : name of reactive metal / name of carbonate salt] 2. [To test gas produced] 3. [Observation] Example 1 Procedure: 1. Magnesium ribbon is added into the aqueous solution X 2. Lower a lighted wooden splinter Observation: A “pop” sound is heard Example 2 Procedure: 1. Calcium carbonate is added into the aqueous solution X 2. Passing the gas through lime water Observation: Lime water turns milky 1 1 2 1 1 1 2 1 1 1 2 1 Total 10
  30. 30. 6 Section B Question Number Explanation Mark  7 (a) Melting point is the temperature at which a solid changes into a liquid at a particular pressure. Because the energy absorbed by the naphthalene is used to overcome the forces of attraction between the molecules of naphthalene. 1 1 1 1 4 7(b) Before condensation  The kinetic energy is high  The particles are very far apart from each other  The attraction forces between particles are very weak. During condensation  The kinetic energy decreases  The particles begin to move closer toward one another / the distance between the particles decrease  The attraction forces between particles become stronger. After condensation  The kinetic energy is low  The particles are packed closely together in an orderly manner  The attraction forces between particles are strong. 1 1 1 1 1 1 1 1 1+1 1 10 7(c)(i) Proton number = 13 Nucleon number = 14 + 13 = 27 1 1 2 7(c)(ii) Number of moles of Y = 27 8.10 = 0.4 Number of moles of Y2O3 = 0.4 ÷ 2 = 0.2 Relative formulas mass of Y2O3 = 2(27) + 3(16) = 102 Mass of Y2O3 = 0.2  102 = 20.4 g 1 1 1 1 4 Total 20
  31. 31. 7 Question Number Explanation Mark  8 (a) Helium atom has two electrons in its valence shell / helium atom has achieved a duplet electron arrangement. Helium atom will not gain, lose nor share electrons with other atoms. Chlorine atom has an electron arrangement of 2. 8. 7, needs one electron to achieve the octet electron arrangement. Thus, two chlorine atoms share one pair of electrons so that both atoms can achieve the octet electron arrangement. 1 1 1 1 4 8(b)(i) Covalent compound 1 1 + 1 3 8(b)(ii) A magnesium atom with an electron arrangement of 2.8.2 // donates 2 valence electron to achieve the stable / octet electron arrangement // 2. 8. A positive magnesium ion, Mg2+ is formed. Two chlorine atoms, each with an electron arrangement of 2.8.7 accepts 1 electron to achieve the stable octet electron arrangement// 2. 8. 8. A negative chloride ion, Cl is formed. Mg2+ and Cl ions are attracted to each other by a strong electrostatic force. 1 1 1 1 1 1 1 7 8(c)(i) Solid sodium chloride cannot conduct electricity, sodium chloride aqueous solution can conduct electricity. In solid state, sodium ions and chloride ions are held together by strong electrostatic forces // are fixed in their position and cannot move freely. In aqueous state, sodium ions and chloride ions are free to move. This enables ions to be discharge at anode and cathode. 1 1 1 1 4 8(c)(ii) Number of moles of NaCl = 0.2  0.05 = 0.01 Mass of 0.01 mole of NaCl = 0.01  58.5 = 0.585 g 1 1 2 Total 20 C ClCl Cl Cl
  32. 32. 8 Section C Question Number Explanation Mark  9 (a) Cryolite is added to aluminium oxide to lower its melting point. Molten aluminium oxide is electrolysed using carbon electrodes. Aluminium ions are discharged at cathode. // Al3+ + 3e  Al Oxide ions are discharged at anode.// 2O2  O2 + 4e 1 1 1 1 4 9(b) Zinc is more electropositive than copper. Zinc atom releases electrons to form zinc ions, Zn2+ in zinc sulphate solution. //Zn(s)  Zn2+ (aq) + 2e The electrons flow from zinc electrode to copper electrode through external circuit. At the copper electrode, the electrons are accepted by the copper(II) ions, Cu2+ to form copper atoms. //Cu2+ (aq) + 2e  Cu(s) 1+1 1 1 1 1 6 Zinc plate Copper plate Copper (II) sulphate solution (1.0 moldm-3 ) Zinc sulphate solution (1.0 moldm-3 ) Salt bridge
  33. 33. 9 9(c) Silver can be used to electroplate the iron key. The electrolyte is silver nitrate solution, [0.5 moldm-3 ]. [or other suitable metal and electrolyte] The silver electrode is connected to positive terminal of battery // act as anode. The iron spoon is connected to negative terminal of battery // act as cathode. The switch is turned on. Anode Half equation : Ag(s)  Ag+ (aq) + e Observation : Silver electrode becomes thinner. Cathode Half equation : Ag+ (aq) + e  Ag(s) Observation : A thin layer of shiny grey solid is deposited on the iron spoon. 1 1 1 1 1+1 1 1 1 1 1 [11] Max. 10 Total 20 Iron spoon Silver Silver nitrate solution, 0.5 moldm -3
  34. 34. 10 Question Number Explanation Mark  10 (a) [Name any insoluble salt] [Name any two suitable solution] [Write correct ionic equation] Example: Lead(II) sulphate Lead(II) nitrate solution and sodium sulphate solution Pb2+ + SO4 2  PbSO4 1 1+1 1 4 10(b) Test for Zn2+ ion Procedure I:  A few drops of sodium hydroxide solution are added into the salt solution of X until in excess. Observation :  White precipitate dissolved in excess sodium hydroxide solution to produce a colourless solution. Procedure II:  A few drops of ammonia solution are added into the salt solution of X until in excess. Observation :  White precipitate dissolved in excess ammonia solution to produce a colourless solution. Inference: Zn2+ ion is present Test for SO4 2+ ion  5 cm3 of hydrochloric acid is added into the salt solution of X follow by 2 cm3 of barium chloride solution. Observation:  White precipitate is formed. Inference: SO4 2+ ion is present. 1 1 1 1 1 1 6
  35. 35. 11 10(c)  Chemicals : sulphuric acid and copper(II) oxide / copper(II) carbonate  50 cm3 of 1.0 moldm-3 sulphuric acid is pour into a beaker and warmed carefully  Copper(II) oxide powder is added a little at a time into the acid using spatula.  The mixture is stir well with a glass rod.  Copper(II) oxide powder is added continuously until some of it no longer dissolves.  The mixture is filtered to remove the excess copper(II) oxide.  The filtrate is pour into an evaporating dish and heated gently to produce a saturated solution / heated until the filtrate is evaporated to about 1/3 of its original volume.  The saturated solution is then allowed to cool to room temperature for crystallisation to occur.  The copper(II) sulphate crystals are filtered and dry by pressing them between a few pieces of filter paper.  H2SO4 + CuO  CuSO4 + H2O 1 1 1 1 1 1 1 1 1 1 [10] Total 20 END OF MARKING SCHEME OF PAPER 2

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