NYGH 2020-S3EOY-IP Chem P2

Class Register Number Name 南洋女子中学校 NANYANG GIRLS' HIGH SCHOOL End-of-Year Examination 2020 Secondary Three Chemistry Paper 2 Theory Paper 1 hour 45 minutes Wednesday 07 October 2020 0845 - 1030 Additional materials: Writing paper READ THESE INSTRUCTIONS FIRST Do not open this booklet until you are told to do so. Write your name, register number and class in the spaces at the top of this page and on any separate answer paper used. Section A (40 marks) Answer all questions. Write your answers in the spaces provided on the question paper. Section B (30 marks) Answer all questions including questions B6, B7 and B8 Either or B8 Or. Write your answers on the separate writing paper provided. At the end of the examination, 1. Fasten all your work securely together; 2. Circle B8 Either (for Either) or B8 Or (for Or) in the grid on the right to indicate the question you have answered; 3. Hand in Section A and Section B separately. INFORMATION FOR CANDIDATES The intended number of marks is given in the brackets [ ] at the end of each question or part question. You are advised to spend no longer than 60 minutes on Section A and no longer than 45 minutes on Section B. The use of approved scientific calculators is allowed. A copy of the periodic table is found on page 15. Paper 1 / 30 Paper 2 Section A / 40 B6 / 10 B7 / 10 B8 Either / B8 Or / 10 Total / 100 Setters: NHK/ OWJ This document consists of 14 printed pages and 2 blank pages. NANYANG GIRLS’ HIGH SCHOOL [Turn over

2020 End-of-Year Examination Secondary Three 2 Nanyang Girls’ High School Setters: NHK/ OWJ Chemistry/ Paper 2 Section A (40 marks) Answer all questions. Write your answers in the spaces provided. A1 Ammonium chloride is a white crystalline salt that is used mainly as a fertiliser and a flavouring agent. It is separated from a mixture with the setup below. (a) What is the property of ammonium chloride that makes it suitable to be separated from the mixture with the setup above? [1] (b) The table below shows some properties of ammonium chloride. decomposition temperature 338 oC solubility highly soluble in water electrical conductivity conducts electricity in aqueous state (i) State the type of bonding(s) found in ammonium chloride. [1] (ii) Ammonium chloride decomposes to form hydrogen chloride gas. Draw a dot-and-cross diagram to show the bonding in hydrogen chloride gas, showing only the valence electrons. [2] cotton plug pure ammonium chloride mixture inverted glass funnel Bunsen burner tripod stand

2020 End-of-Year Examination Secondary Three 3 Nanyang Girls’ High School Setters: NHK/ OWJ Chemistry/ Paper 2 [Turn Over (c) Plugs of cotton wool soaked respectively in concentrated aqueous ammonia and concentrated hydrochloric acid are inserted at the same time into the open ends of a horizontal tube as shown in the diagram below. The ends are sealed and after some time, white fumes of ammonium chloride are observed. At which position will the white fumes be observed? [1] Total [5] concentrated aqueous ammonia concentrated hydrochloric acid A B C

2020 End-of-Year Examination Secondary Three 4 Nanyang Girls’ High School Setters: NHK/ OWJ Chemistry/ Paper 2 A2 This question is about the reaction of metal carbonates with acid. (a) (i) Write an ionic equation for the reaction between nitric acid and silver carbonate. [2] (ii) 8.00 g of silver carbonate reacts with 150 cm3 of 0.200 mol dm–3 nitric acid. Calculate the volume of gas that is formed by this reaction. [3] (iii) The graph for the reaction of 8.00 g of silver carbonate reacts with 150 cm3 of 0.200 mol dm–3 nitric acid is shown below. On the same axes, draw the graph when 8.00 g of silver carbonate is reacted with 150 cm3 of 0.200 mol dm–3 hydrochloric acid. Label this graph as A. On the same axes, draw the graph when 8.00 g of silver carbonate is reacted with 150 cm3 of 0.150 mol dm–3 sulfuric acid. Label this graph as B. [2] volume of gas / cm3 time / s

2020 End-of-Year Examination Secondary Three 5 Nanyang Girls’ High School Setters: NHK/ OWJ Chemistry/ Paper 2 [Turn Over (b) State a variable other than concentration of acid and temperature that can increase the rate of the reaction between silver carbonate with nitric acid, explaining your answer in terms of collision between particles. [3] Total [10] A3 Study the reaction scheme given below. (a) Identify unknowns A to E, shown in the reaction scheme above. [5] A D B E C (b) Write a chemical equation, including state symbols when gas B is bubbled into aqueous calcium hydroxide to form a white precipitate. [2] Total [7] solution D aqueous sodium hydroxide + solid C heat 2 mol ammonia 1 mol white solid A aqueous sodium nitrate green precipitate E ammonium sulfate aqueous iron(II) sulfate 1 mol gas B white precipitate aqueous calcium hydroxide 1 mol water warm

2020 End-of-Year Examination Secondary Three 6 Nanyang Girls’ High School Setters: NHK/ OWJ Chemistry/ Paper 2 A4 A precipitation reaction between aqueous barium hydroxide and dilute sulfuric acid is investigated. Six test tubes, A to F contain 10.0 cm3 of 0.500 mol dm–3 aqueous barium hydroxide and different volumes of 1.00 mol dm–3 dilute sulfuric acid were added. Precipitation occurs in all test tubes and the height of the precipitate in each test tube is measured and recorded in the graph below. (a) Write a balanced chemical equation, including state symbols for the reaction between aqueous barium hydroxide and dilute sulfuric acid. [2] (b) Two drops of Universal indicator are added to each test tube. State the colour of the Universal indicator in the following test tubes. (i) test tube B [1] (ii) test tube E [1] (c) The electrical conductivity of each test tube is measured after the reaction. Sketch a graph to show the change of electrical conductivity from test tube A to test tube F. [2] Total [6] electrical conductivity/ µScm–1 test tube A B C D E F volume of H2SO4(aq)/ cm3 height of precipitate/ cm 1 2 3 4 5 6 7 8 1.0 2.0 3.0 4.0 5.0 6.0 7.0 0 A B C D E F

2020 End-of-Year Examination Secondary Three 7 Nanyang Girls’ High School Setters: NHK/ OWJ Chemistry/ Paper 2 [Turn Over A5 4.21 g of a solid mixture containing sodium ethanedioate, Na2C2O4 and ethanedioic acid dihydrate, H2C2O4•2H2O was placed in a volumetric flask and made up to 250 cm3. This solution was labeled P. Two separate titrations were carried out using this solution P. (a) In the first titration, 25.0 cm3 of solution P was titrated with 0.200 mol dm–3 acidified potassium manganate(VII) solution. When 26.50 cm3 of acidified potassium manganate(VII) solution was added, the solution in the conical flask changed colour. The ionic equation for this titration reaction is as follows: 2MnO4–(aq) + 5C2O42–(aq) + 16H+(aq) → 2Mn2+(aq) + 8H2O(l) + 10CO2(g) (i) State the colour change of acidified potassium manganate(VII) when a few drops of it was added to solution P. [1] (ii) Write the half ionic equation when ethanedioate ions, C2O42– forms carbon dioxide, CO2. [2] (iii) Calculate the number of moles of manganate(VII) ions, MnO4– added. [1] (iv) Calculate the number of moles of ethanedioate ions, C2O42– reacted. [1]

2020 End-of-Year Examination Secondary Three 8 Nanyang Girls’ High School Setters: NHK/ OWJ Chemistry/ Paper 2 (b) In the second titration, 25.0 cm3 of solution P was