2022 FHSS Chem Prelims P2

Candidate Name: Class Index No. FUHUA SECONDARY SCHOOL 4E Secondary Four Express Preliminary Examination 2022 Fuhua Secondary Fuhua Secondary Fuhua Secondary Fuhua Secondary Fuhua Secondary Fuhua Secondary Fuhua Secondary Fuhua Secondary Fuhua Secondary Fuhua Secondary Fuhua Secondary Fuhua Secondary Fuhua Secondary Fuhua Secondary Fuhua Secondary Fuhua Secondary Fuhua Seconda ry Fuhua Secondary Fuhua Secondary Fuhua Secondary F uhua Secondary Fuhua Secondary Fuhua Secondary Fuhua Secondary Fuhua Secondary Fuhua Secondary Fuhua Secondary Fuhua Secondary Fuhua Secondary Fuhua Secondary Fuhua Secondary Fuhua Secondary Fuhua Secondary Fuhua Secondary Fuhua Seconda ry Fuhua S econdary ____________________________________________________________________________________________________________ CHEMISTRY 6092/02 Paper 2 23 August 2022 1040 – 1225 1 hour 45 minutes ____________________________________________________________________________________________________________ READ THESE INSTRUCTIONS FIRST Write your name, class and index number 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. Section A Answer all questions in the spaces provided. Section B Answer all three questions, the last question is in the form of either/or. Answer all questions in the spaces provided. 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 20. The use of an approved scientific calculator is expected, where appropriate. PARENT’S SIGNATURE FOR EXAMINER’S USE Section A Section B Total /50 /30 /80 Setter: Mdm Hia Soo Ching Vetters: Mr Elton Tan, Ms Veron Lee, Ms Nur Hanis & Ms Choo Hui En This document consists of 20 printed pages.

2 Section A Answer all questions in this section in the spaces provided. The total mark for this section is 50. A1 The diagram below shows part of the Periodic Table. Answer the following questions using only the elements shown in the diagram above. Each element can be used once, more than once or not at all. (a) Which two elements react together to give the most vigorous reaction? [1] (b) (i) Which two elements in Period 3 form an ionic compound with a formula of the type Y2Z? [1] (ii) Draw a dot and cross diagram to represent the bonding in Y2Z. Show only outer electrons. [2] (c) Which elements react with oxygen to give an oxide that dissolves in both aqueous sodium hydroxide and dilute hydrochloric acid? [1] (d) Describe the trends in melting point and reactivity for Group I and Group VII. [2] (e) Construct a balanced chemical equation when a piece of calcium is added to water. [1] [Total: 8]

3 A2 In a particular factory, ammonia generated in a small -scale ammonia generator is used to treat waste gases containing nitrogen oxides. This treatment converts nitrogen monoxide to nitrogen and water. (a) (i) Write an equation to show the reaction between nitrogen monoxide and ammonia. [1] (ii) Explain, in terms of oxidation state, why the reaction in (a)(i) is a redox reaction. [2] (b) Explain how waste gases released by the factory affects the environment if they are not treated by reacting with ammonia. [2] (c) Suggest one advantage, other than cost, of producing ammonia on-site by this method rather than having ammonia delivered from a plant at another location. [1] (d) In terms of colliding particles, explain why increasing the temperature of the ammonia generator is necessary. [2]

4 (e) Ammonia has a boiling point of -33.3C. Explain, in terms of structure and bonding, why ammonia has a low boiling point. [2] [Total: 10] A3 The diagram below shows the structure of some polymers A, B, C and D. A B C D (a) A sample of C contains molecules with an average relative molecular mass of 14 000. How many carbon atoms are there in an average molecule of the polymer? [1] (b) Describe a test to distinguish between polymer A and C. [2]

5 (c) Which of these statements would you predict to be true and which to be false? Put a tick () in one box in each row. true false D is a polyester. Water is formed as a by-product when monomers react to form A and B. The empirical formula of C is the same as its monomer. One of the monomers that react to form B must be an alcohol. [2] (d) Draw the displayed formulae of the monomers that react to form A. [2] (e) (i) Draw the structural formula of the monomer that react to form D. [1] (ii) The monomer in (e)(i) can be formed by reacting an acid and an alcohol under suitable conditions. State the name and formula of the alcohol. [1] (iii) A student states that the acid in (e)(ii) is butanoic acid. Do you agree with his statement? Explain your reasoning. [1] (f) Some polymers are non-biodegradable. Explain why being non-biodegradable is both an advantage and a disadvantage. [2] [Total: 12]

6 A4 A student carried out a series of experiments according to the following procedure: • She added excess magnesium powder to 25.0 cm3 of various aqueous salt solutions with the same concentration. • She calculated the maximum temperature rise in each experiment. She tabulated the results obtained in the table below. experiment solution maximum temperature rise / C 1 copper(II) sulfate 42.0 2 lead(II) nitrate 32.0 3 calcium chloride 0.0 4 sodium nitrate 0.0 5 sulfuric acid 38.0 6 zinc sulfate 14.0 (a) Explain why there is no rise in temperature for experiments 3 and 4. [1] (b) (i) Predict the temperature rise when she added excess magnesium powder to 25.0 cm3 of iron(II) sulfate of the same concentration. [1] (ii) Write an ionic equation for the reaction in (b)(i). [1] (iii) Suggest the temperature rise when she added excess magnesium powder to 25.0 cm3 of ethanoic acid of the same concentration. Explain your answer. [3]

7 (c) Complete the energy profile diagram for experiment 1. Your diagram should include • formulae of reactants and products • enthalpy change of reaction • activation energy [2] [Total: 8]

8 A5 The following figure shows an electrolytic setup. Electrodes P and Q are made of metal M. Electrodes R and S are made of graphite. X and Y are terminals of a battery. When the switch is closed and electrolysis is allowed to run for some time, the ratio of the volume of gases produced at R and S is 2:1 respectively. (a) (i) Deduce the polarity of terminals X and Y of the battery. [1] (ii) Write an overall equation for the reaction occurring in cell 2. [1] (iii) In cell 2, concentrated aqueous magnesium chloride is used instead of dilute magnesium chloride. Give one similarity and one difference between the products of the electrolysis of dilute and concentrated aqueous magnesium chloride. [2] (b) (i) Construct the ionic equations, including state symbols for the reactions occurring at electrode P and Q respectively. electrode P: electrode Q: [2] (ii) If the relative atomic mass of M is 64, describe the observation at electrode P. [1] aqueous M(NO3)2 cell 1 cell 2 dilute magnesium chloride

9 (iii) If 150 cm3 of gas is produced