2811_Jan_03QP -

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Unformatted text preview: 00$? RECOGNISING ACHIEVEMENT OXFORD CAMBRIDGE AND RSA EXAMINATIONS Advanced Subsidiary GCE CHEMISTRY 2811 Foundation Chemistry Friday 17 JANUARY 2003 Morning 1 hour Candidates answer on the question paper. Additional materials: Scientific calculator Data Sheet for Chemistry . Candidate Candidate Name Centre Number Number TIME 1 hour INSTRUCTIONS TO CANDIDATES . Write your name in the space above. . Write your Centre number and Candidate number in the boxes above. 0 Answer all the questions. 0 Write your answers in the spaces on the question paper. 0 Read each question carefully and make sure you know what you have to do before starting your answer. INFORMATION FOR CANDIDATES o The number of marks is given in brackets I ] at the end of each question or part question. 0 You will be awarded marks for the quality of written communication where this is indicated in the question. . You may use a scientific calculator. 0 You may use the Data Sheet for Chemistry. 0 You are advised to show all the steps in any calculations. FOR EXAMINER’S USE This question paper consists of 10 printed pages and 2 blank pages. 2 For Examiner's , Use Answer all the questions. 1 Gallium, atomic number 31, exists naturally as a mixture of its isotopes, 6S’Ga and 71Ga. (a) Complete the table below to show the atomic structure of each isotope of gallium. number of isotope protons neutrons electrons 69Ga 71Ga [2] (b) A mass spectrometer can be used to identify the isotopes in a sample of an element. The diagram below shows a mass spectrometer. Complete the diagram by adding the names of the processes that take place in each of the four labelled regions. ——> to the pump vapour of /' element 3 (c) A sample of gallium was analysed in a mass spectrometer to produce the mass spectrum below. The relative atomic mass of gallium can be calculated from this mass spectrum. 100 80 60 4o °/o composition 2O 65 70 75 relative isotopic mass (i) Define the term relative atomic mass. ............................................................................................................................ [3] (ii) Estimate the percentage composition of each isotope present in the sample. [1] (iii) Calculate the relative atomic mass of this sample of gallium. Your answer should be given to three significant figures. answer ......................................... [2] [Total : 1 2] For Examiner’s Use 2 4 When magnesium is heated in air, it reacts with oxygen to form magnesium oxide. (a) (b) (c) (d) 2Mg(S) + 02(9) -—) 2M90(S) Complete the electronic configuration of a magnesium atom. 1s2 ............................................................................................................................. [1] What is the oxidation state of magnesium in (i) Mg .................................... [1] (ii) MgO? ............................... [1] When magnesium is heated in air, it also reacts with nitrogen to form solid magnesium nitride, Mg3N2. (i) Construct an equation, with state symbols, for this reaction between magnesium and nitrogen. ............................................................................................................................ [2] (ii) Suggest why magnesium reacts with air to form much more MgO than MgaNz. .................................................................................................................................. ............................................................................................................................ [1] Magnesium oxide has an extremely high melting point which makes it suitable as a lining for furnaces. Explain, in terms of its structure and bonding, why magnesium oxide has this property. .......................................................................................................................................... .......................................................................................................................................... For Examiner's Use 5 For Examiner's u (e) When magnesium oxide is added to warm dilute nitric acid, a reaction takes place 58 forming a solution of magnesium nitrate. MgO(s) + 2HNOa(aq) ——) Mg(N03)2(aq) + H200) A student reacted 0.0500 mol MgO with 0.400 moi dm'3 nitric acrd. (i) What would you see during this reaction? ............................................................................................................................ [1] (ii) Calculate the mass of MgO that reacted. [2] (iii) Calculate the volume of 0.400 moldm‘3 HNO3 required to react exactly With this amount of MgO. [2] (f) The solution formed in this reaction contains ions. (i) Why does this solution conduct electricity? ............................................................................................................................ [1] (ii) State the formulae of two ions present in this solution. ............................................................................................................................ [2] [Total : 17] 3 6 This question is about chlorine and chlorine compounds. (8) (b) (C) Chlorine reacts with water to form a solution. C12(g) + H200) ——) HCl(aq) + HOCl(aq) (i) Why IS chlorine added to water on a large scale? ............................................................................................................................ [1] (ii) Green universal indicator is added to this solution. What colour changes would you see immediately ........................................................................................................ [1] after some time? ................................................................................................ [1] Describe a simple test that you could carry out to show that chloride ions are present in a sample of sea water. reagent ............................................................................................................................ observation ...................................................................................................................... equaflon ........................................................................................................................... [3] Some dry-cleaning solvents include the chlorine compound Perc. Perc has the followmg percentage composition by mass: Cl. 85.6%: C, 14.4%. The relative molecular mass of Perc is 166. (i) Calculate the molecular formula of Perc. [3] (ii) Suggest why Perc would not react in the test in (b). For Examiner’s Use 7 For Examiner’s u (d) Sodium chlorate, NaClOa, is a chlorine compound used as a weed killer. 59 When heated, NaClO3 releases oxygen gas. 2NaC103(s) -—) 2NaCl(s) + 302(g) Calculate the volume of 02 that can be formed at room temperature and pressure by heating 4.26 g of NaClOa. 1 mol of gas molecules occupies 24.0 dm3 at room temperature and pressure. [4] [Total : 14] 4 8 The first six successive ionisation energies of an element D are shown in Table 4.1 below. Table 4.1 ionisation energy/ kJ mol’1 element 1st l 2nd 3rd 4th 5th ‘ 6th D 1086 l 2353 4621 6223 37832 I 47278 (a) Define the term first ionisation energy. .......................................................................................................................................... .......................................................................................................................................... .................................................................................................................................... [3] (b) Write an equation, with state symbols, to represent the third ionisation energy of element D. .................................................................................................................................... [2] (c) Use Table 4.1 to deduce which group of the Periodic Table contains element D. Explain your answer. group ............................................................................................................................... explanation ...................................................................................................................... For Examiner’s Use 9 For Examiner's u 5 In this question, one mark will be awarded for the quality of written communication. se in the Periodic Table, describe and explain the trend in atomic radii shown by c the Group 2 elements Be-Ra o the Period 3 elements, Na-Ar. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ................................................................................................................................................. ............................................................................................................................................. [8] Quality of Written Communication [1] [Total : 9] ...
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