NYGH 2010-S3EOY-Chem P2

Class Register Number Name 南洋女子中学校 NANYANG GIRLS’ HIGH SCHOOL End-of-Year Examination 2010 Secondary Three CHEMISTRY 1 hour 45 minutes Paper 2 Theory Paper 09 15 – 11 00 Friday 15 October 2010 Additional materials: Writing papers 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 9, 10 and 11 Either or 11 Or. Write your answers on the separate writing paper provided. At the end of the examination, 1. Hand in Section A and Section B separately; 2. Write an E (for Either) or an O (for Or) next to the number 11 in the grid below to indicate which question you have answered. INFORMATION FOR CANDIDATES Examiner’s Use Section A Section B 9 10 11 Total 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 one hour on Section A and no longer than 45 minutes on Section B. You are allowed to use an approved scientific calculator. Setters: LSC and ET This document consists of 14 printed pages. NANYANG GIRLS’ HIGH SCHOOL [Turn over

2010 End-of-Year Examination Secondary Three 2 Nanyang Girls’ High School Section A Answer all questions. Write your answers in the spaces provided. A1 (a) What are the differences in the arr angement and motion of the particles in a solid as compared to that in a gas? Give a reason for these differences. [2] (b) A certain gas X , has a relative molecular mass of 64. Another gas, Y has a relative molecular mass of 28. Both ar e at the same tem perature. Are the particles in the two gases moving at the same speed? Explain your reasoning. [2] [Total:4] A2 (a) The figure below shows an experiment to find the boiling point of a liquid Z. (i) Would this method be suitable for fi nding the boiling point of a volatile liquid? Explain your answer. [2] liquid Z boiling stones round bottomed flask Setters: LSC and ET Chemistry /II

2010 End- of-Year Examination Secondary Three 3 Nanyang Girls’ High School ( i i ) The thermometer showed a constant reading at 70 oC and then again at 120oC. What conclusion can you draw from this observation? [1] (b) The colouring in a fizzy drink was extr acted by a solvent. Two drops of the solution were placed at the centre of a circular filter paper and allowed to dry. Drops of pure solvent were slowly added to the centre of the filter paper. After some time, four coloured circles were seen, as shown in the diagram below. (i) What is the name of the process described above? [1] (ii) How many different dyes are there in the fizzy drink? [1] [Total:5] . Filter paper orange yellow red blue centre of filter paper Setters:LSC and ET Chemistry /II [Turn over

2010 End-of-Year Examination Secondary Three 4 Nanyang Girls’ High School A3 Carbonyl chloride, COC I2, is a colourless and poisonous gas that is also known as phosgene. It is needed for the production of insecticides and plastics. It is produced from the reaction of carbon monoxide and chlorine gas in the reaction vessel as shown in the diagram below. The reaction vessel is cooled below 8 oC to collect the phosgene liquid. (a) Draw a dot and cross diagram to show the bonding in COCI 2. Your diagram should only show the valence electrons. [2] (b) Would you expect phosgene to be a solid, a liquid or a gas at room temperature? Give a reason in terms of its structure and bonding. [2] [Total:4] carbon monoxide chlorine phosgene tap for removal of phosgene Setters: LSC and ET Chemistry /II

2010 End- of-Year Examination Secondary Three 5 Nanyang Girls’ High School A4 (a) A sample of hydrated c opper(II) sulfate, CuSO 4.5H2O, was heated in the apparatus shown below. On gentle heating, the blue cr ystals changed to a white solid P and a neutral liquid Q was collected in the tube cooled by cold water. Name the white solid P and the neutral liquid Q. White solid P: Neutral liquid Q: [2] (b) On stronger heating, the white solid P changed to a black solid R and a gas was evolved which dissolved in liquid Q to from solution S. The indicator paper turned red as solution S was formed. Addition of aqueous barium chloride to solution S gave a white precipitate, W. (i) Name the white precipitate, W. [1] (ii) Suggest an identity for solution S. [1] [Total:4] Setters:LSC and ET Chemistry /II [Turn over

2010 End-of-Year Examination Secondary Three 6 Nanyang Girls’ High School A5 (a) Sodium nitrate is a salt which can be prepared by reacting an alkali with an acid, using the titration method. (i) Name an alkali and an acid which would react together to produce sodium nitrate. alkali: acid: [2] (ii) Write an ionic equation, with state symbols, for the reaction. [2] (b) Lead(II) chloride is a salt which can be prepared by the precipitation method. (i) Name suitable reagents for the precipitation of lead(II) chloride. Reagent 1: Reagent 2: [2] (ii) Explain why the precipitation method is suitable for the preparation of lead(II) chloride. [2] [Total:8] Setters: LSC and ET Chemistry /II

2010 End- of-Year Examination Secondary Three 7 Nanyang Girls’ High School A6 In a reaction, silver nitrate decomposed on heating according to the equation below. 2AgNO3 → 2Ag + 2NO2 + O2 Given that 42.5 g of silver nitrate completely decomposed when heated in an experiment: (a) Calculate the mass of silver metal formed. [2] (b) Calculate the volume of nitrogen dioxide, in dm 3, gas formed at r.t.p. [2] (c) Calculate the number of moles of oxygen gas formed. [2] [Total:6] Setters:LSC and ET Chemistry /II [Turn over

2010 End-of-Year Examination Secondary Three 8 Nanyang Girls’ High School A7 A solution contains 5.00 g of impure phosphoric acid, H 3PO4, per dm3. In a titration, 25.0 cm 3 of the acid soluti on reacted with 20.80 cm 3 of 0.12 mol/dm 3 sodium hydroxide according to the equation shown below. H3PO4(aq) + 3NaOH(aq) → Na3PO4(aq) + 3H2O(I) (a) Calculate the number of moles of sodium hydroxide that reacts with the acid. [2] (b) Calculate the concentration of pure phosphoric acid in g/dm 3, present in the solution. [2] (c) Calculate the percentage purity of the phosphoric acid. [1] [Total:5] Setters: LSC and ET Chemistry /II

2010 End- of-Year Examination Secondary Three 9 Nanyang Girls’ High School A8 The reaction between zinc granules and dilute sulfuric acid at 25 oC can be made to go faster by adding a small amount of copper powder. In the experiment, 0.65 g of zinc granules and 100 cm 3 of 0.2 mol/dm 3 sulfuric acid are allowed to react. (a) Calculate t