NYGH 2021-S3EOY-IP Chem P2

Class Register Number Name End-of-Year Examination 2021 Secondary 3 IP CHEMISTRY Paper 2 1hour 45 minutes Wednesday 6 October 0845 – 1030 READ THESE INSTRUCTIONS FIRST Write your name, register number and class in the spaces at the top of this page. Write in dark blue or black pen. You may use a pencil for any diagrams or graphs. Do not use staples, paper clips, glue or correction fluid / tape. Section A Answer all questions in the spaces provided. You are advised to spend no longer than 1 hour on Section A, and no longer than 45 minutes on Section B. The number of marks is given in brackets [ ] at the end of each question or part question. A copy of the Periodic Table is on page 12. The use of an approved scientific calculator is expected, where appropriate. Section A (40 marks) Section B (30 marks) Total (70 marks) This document consists of 12 printed pages and 0 blank pages. Setter(s): FKD/JK NANYANG GIRLS' HIGH SCHOOL [Turn over A

2 Setters: FKD/JK Chemistry Paper 2 Section A (40 marks) Answer all questions. Write your answers in the spaces provided. A1 Group 17 elements show trends in their melting points and boiling points. Table 1 element melting point/oC boiling point/ oC chlorine 101 35 bromine 7 59 iodine 114 184 (a) The change in temperature against time graph for bromine is represented in Figure 1. Figure 1 (i) State the process occurring at point DE. Hence, explain why temperature remained unchanged. [3] Temperature Time A B C D E F

3 Setters: FKD/JK Chemistry Paper 2 [Turn Over (ii) Describe the arrangement and movement of the particles at point A. [2] (b) Describe and explain the trend in boiling point down the group 17 elements. [3] Total [8]

4 Setters: FKD/JK Chemistry Paper 2 A2 The radii of atoms and ions can be measured. Table 2 shows information about atomic radii and ionic radii of some of the group 1 elements. Table 2 element number of protons electronic configuration of atom atomic radius/pm electronic configuration of +1 ion ionic radius/pm lithium 3 2.1 152 2 68 sodium 11 2.8.1 185 98 potassium 19 2.8.8.1 227 133 (1 000 000 000 000pm = 1m) (a) Complete the table to show the electronic configuration in the ions of Group 1. [1] (b) (i) Describe and explain the trend in atomic radii down Group 1. [3] (ii) Describe and e xplain the change in the radius when a lithium atom form s a lithium ion. [2]

5 Setters: FKD/JK Chemistry Paper 2 [Turn Over (c) (i) The group 1 elements react with water vigorously. Write an equation to illustrate the reaction between lithium and water. State symbols are not required. [1] (ii) Using the data for atomic radius given in Table 2, suggest the relationship between reactivity and atomic radii of the Group 1 elements. [2] Total [9]

6 Setters: FKD/JK Chemistry Paper 2 A3 When aqueous ammonia is added to an aqueous solution of an aluminium salt, a precipitate is formed as an amorphous gelatinous mass. When dried, this precipitate forms a white crystalline compound called boehmite, consisting of Al, O and H atoms. A 100g sample of boehmite was found to contain 53.3g of oxygen a toms and 1.7g of hydrogen atoms have the following composition by mass: Al, 45.0%; O, 53.3%; H, 1.7%. (a) Calculate the mass of aluminium atoms present in the sample. [1] (b) (i) Show, with calculations, that the empirical formula of boehmite is AlO2H. [2] (ii) The formation of boehmite from aluminium ions and hydroxide produces water as a by-product. Write a balanced ionic equation, with state symbols, for the formation of boehmite and its by-products from aluminium ions and hydroxide ions. [2]

7 Setters: FKD/JK Chemistry Paper 2 [Turn Over (c) Aluminium metal can be found in metal ores which may also contain zinc impurities. The reaction of a sample of these ores with nitric acid results in the formation of a solution containing these metal ions. Describe a test and the results that can be used to distinguish between the two ions in a solution. Test: Observation for Al3+: Observation for Zn2+: [3] (d) Metallic aluminium is very reactive with atmospheric oxygen to form a thin layer of aluminium oxide, Al2O3, which is resistant to corrosion. In the space below, draw the “dot and cross” diagram of aluminium oxide. [2] Total [10]

8 Setters: FKD/JK Chemistry Paper 2 A4 25.0 cm 3 of diluted hydrogen peroxide solution , FA2 , completely reacts with 22.50 cm3 of 0.0200 mol dm−3 acidified potassium manganate(VII) solution. The ionic equation for the reaction is given below. 2MnO4(aq)+ 5H2O2 (aq) + 6H+ (aq)  2Mn2(aq) + 5O2 (g) + 8H2O (l) (a) Calculate the number of moles of manganate ions, MnO 4- required to react with 25.0 cm3 of diluted H2O2, FA2. [1] (b) Calculate the number of moles of H2O2 present in 25.0 cm3 of FA2. [1] (c) Hence, calculate the number of moles of H2O2 present in 500 cm3 of FA2. [1]

9 Setters: FKD/JK Chemistry Paper 2 [Turn Over (d) FA2 solution is prepared by diluting FA1 which contains hydrogen peroxide, H2O2, of an unknown concentration. 12.50 cm3 of FA1 was diluted to a final total volume of 500 cm 3 with distilled water to prepare FA2. Given that the number of moles of H2O2 present in 500 cm3 of FA2 is equivalent to the number of moles in 12.5 cm 3 of H2O2 in FA1, calculate the concentration of H 2O2 in FA1. [1] Total [4]

10 Setters: FKD/JK Chemistry Paper 2 A5 Some tests were carried on a blue solution that contains 2 unknown cations and 2 anions. The flowchart below shows the tests conducted on the solution.