GCSE Additional Science June 2008 Chemistry paper B

For Examiner’s Use General Certifi cate of Secondary Education June 2008 ADDITIONAL SCIENCE CHY2H Unit Chemistry C2 CHEMISTRY Unit Chemistry C2 Higher Tier Thursday 5 June 2008 9.00 am to 9.45 am For this paper you must have: 􀁺 the Data Sheet (enclosed). You may use a calculator. Time allowed: 45 minutes Instructions 􀁺 Use black ink or black ball-point pen. 􀁺 Fill in the boxes at the top of this page. 􀁺 Answer all questions. 􀁺 You must answer the questions in the spaces provided. Answers written in margins or on blank pages will not be marked. 􀁺 Do all rough work in this book. Cross through any work you do not want to be marked. Information 􀁺 The maximum mark for this paper is 45. 􀁺 The marks for questions are shown in brackets. 􀁺 You are expected to use a calculator where appropriate. 􀁺 You are reminded of the need for good English and clear presentation in your answers. Advice 􀁺 In all calculations, show clearly how you work out your answer. CHY2H H Surname Other Names Centre Number Candidate Number Candidate Signature (JUN08CHY2H01) G/K30559 6/6/6/6 For Examiner’s Use Question Mark Question Mark 1 3 2 45678 Total (Column 1) Total (Column 2) TOTAL Examiner’s Initials2 Areas outside the box will not be scanned for marking (02) G/K30559/Jun08/CHY2H Answer all questions in the spaces provided. 1 Toothpastes often contain fluoride ions to help protect teeth from attack by bacteria. Some toothpastes contain tin(II) fluoride. This compound has the formula SnF2 . 1 (a) Calculate the relative formula mass (Mr) of SnF2 . Relative atomic masses: F = 19; Sn = 119 ............................................................................................................................................ ............................................................................................................................................ ............................................................................................................................................ ............................................................................................................................................ Relative formula mass (Mr) = .......................................... (2 marks) 1 (b) Calculate the percentage by mass of fluorine in SnF2 . ............................................................................................................................................ ............................................................................................................................................ ............................................................................................................................................ ............................................................................................................................................ Percentage by mass of fluorine = .......................................... % (2 marks)3 Turn over 􀀸 (03) G/K30559/Jun08/CHY2H Areas outside the box will not be scanned for marking 1 (c) A tube of toothpaste contains 1.2 g of SnF2 . Calculate the mass of fluorine in this tube of toothpaste. ............................................................................................................................................ ............................................................................................................................................ ............................................................................................................................................ ............................................................................................................................................ Mass of fluorine = .......................................... g (1 mark) 1 (d) The diagram represents the electron arrangement of a fluorine atom. XXX X X X X XX Explain how a fluorine atom can change into a fluoride ion, F–. ............................................................................................................................................ ............................................................................................................................................ ............................................................................................................................................ ............................................................................................................................................ (2 marks) ____ 7 Turn over for the next question4 Areas outside the box will not be scanned for marking (04) G/K30559/Jun08/CHY2H 2 A student investigated the electrolysis of copper sulfate solution. The student’s method is shown in the box. Two clean pieces of copper were weighed. One piece was used as the positive electrode and the other piece was used as the negative electrode. The circuit was set up as shown in the diagram. + – Lamp Power supply Positive electrode Negative electrode Copper sulfate solution After the electrolysis, the pieces of copper were: 􀁺 washed with distilled water 􀁺 washed with propanone (a liquid with a lower boiling point than water) 􀁺 allowed to dry 􀁺 weighed. 2 (a) Explain why the electrode would dry faster when washed with propanone instead of water. ............................................................................................................................................ ............................................................................................................................................ (1 mark) 2 (b) The student’s results are given in the table. Positive electrode Negative electrode mass of electrode before electrolysis, in grams 16.41 15.46 mass of electrode after electrolysis, in grams 16.10 15.75 The mass of the positive electrode decreased by 0.31 g.5 (05) G/K30559/Jun08/CHY2H Areas outside the box will not be scanned for marking 2 (b) (i) What is the change in mass of the negative electrode? ......................................... g (1 mark) 2 (b) (ii) The mass lost by the positive electrode should equal the mass gained by the negative electrode. Suggest two reasons why the results were not as expected. 1 ............................................................................................................................... .................................................................................................................................. 2 ............................................................................................................................... .................................................................................................................................. (2 marks) 2 (c) Describe and explain how electrolysis is used to make pure copper from a lump of impure copper. ............................................................................................................................................ ............................................................................................................................................ ............................................................................................................................................ ............................................................................................................................................ ............................................................................................................................................ ............................................................................................................................................ ............................................................................................................................................ ............................................................................................................................................ (4 marks) ____ 8 Turn over for the next question Turn over 􀀸6 Areas outside the box will not be scanned for marking (06) G/K30559/Jun08/CHY2H 3 Copper sulfate (CuSO4) is a salt that has many uses. An aqueous solution of copper sulfate can be made by reacting copper oxide (CuO) with an acid. 3 (a) (i) Name this acid. ......................................................................................................... (1 mark) 3 (a) (ii) Write a balanced symbol equation, including state symbols, for this reaction. .................................................................................................................................. (2 marks) 3 (b) Copper oxide reacts much faster with acid at 40 ºC than at 20 ºC. Explain why in terms of particles. ............................................................................................................................................ ............................................................................................................................................ ............................................................................................................................................ ............................................................................................................................................ (2 marks) ____ 57 (07) G/K30559/Jun08/CHY2H Areas outside the box will not be scanned for marking 4 Bricks made from silica (silicon dioxide) are used to line furnaces that operate at high temperatures. Part of the structure of silica is shown in the diagram. Oxygen atom Silicon atom Suggest and explain why silica is used to make bricks for high-temperature furnaces. In your answer, you should refer to the structure of, and bonding in, silica. ..................................................................................................................................................... ..................................................................................................................................................... ..................................................................................................................................................... ..................................................................................................................................................... ..................................................................................................................................................... ..................................................................................................................................................... ..................................................................................................................................................... ..................................................................................................................................................... (4 marks) ____ 4 Turn over 􀀸8 Areas outside the box will not be scanned for marking (08) G/K30559/Jun08/CHY2H 5 Cosmetic powders were widely used in ancient Egypt. Cosmetic powders that may have been used in face paints have been analysed. These powders contained compounds that are rare in nature. The compounds must have been made by the ancient Egyptians using chemical reactions.9 Turn over 􀀸 (09) G/K30559/Jun08/CHY2H Areas outside the box will not be scanned for marking 5 (a) One of these compounds is called phosgenite. Analysis of this compound shows that it contains: 76.0 % lead (Pb) 13.0 % chlorine (Cl) 2.2 % carbon (C) 8.8 % oxygen (O) Calculate the empirical formula of this compound. To gain full marks you must show all your working. Relative atomic masses: C = 12 ; O = 16 ; Cl = 35.5 ; Pb = 207 ............................................................................................................................................ ............................................................................................................................................ ............................................................................................................................................ ............................................................................................................................................ ............................................................................................................................................ ............................................................................................................................................ ............................................................................................................................................ ............................................................................................................................................ (4 marks) 5 (b) Another compound that the ancient Egyptians used is laurionite. The reaction used to make laurionite can be represented by this equation: PbO(s) + NaCl(aq) + H2O(1) → PbOHCl(s) + NaOH(aq) laurionite 5 (b) (i) Explain why the pH of the solution increases as the reaction takes place. .................................................................................................................................. .................................................................................................................................. (1 mark) 5 (b) (ii) How could laurionite be separated from the other product when the reaction is complete? .................................................................................................................................. .................................................................................................................................. (1 mark) ____ 610 Areas outside the box will not be scanned for marking G/K30559/Jun08/CHY2H 6 Read the article about the use of nanoparticles in sun creams. Sun creams Many sun creams use nanoparticles. These sun creams are very good at absorbing radiation, especially ultraviolet radiation. Owing to the particle size, the sun creams spread more easily, cover better and save money because you use less. The new sun creams are also transparent, unlike traditional sun creams which are white. The use of nanoparticles is so successful that they are now used in more than 300 sun cream products. Some sun creams contain nanoparticles of titanium oxide. Normal-sized particles of titanium oxide are safe to put on the skin. For this reason some chemical companies have assumed that nanoparticles of titanium oxide are also safe without doing further testing. It is thought that nanoparticles can pass through the skin and travel around the body more easily than normal-sized particles. It is also thought that nanoparticles might be toxic to some types of cell, such as skin, bone, brain and liver cells. 6 (a) Explain why nanoparticles pass through the skin and travel around the body more easily than normal-sized particles of titanium oxide. ............................................................................................................................................ ............................................................................................................................................ ............................................................................................................................................ ............................................................................................................................................ (2 marks) 6 (b) Explain why sun creams containing nanoparticles should be tested further. ............................................................................................................................................ ............................................................................................................................................ (1 mark) 6 (c) Suggest why some companies that make sun creams might not want to do more tests. ............................................................................................................................................ ............................................................................................................................................ ............................................................................................................................................ ............................................................................................................................................ (2 marks) ____ 5 (10)11 Turn over 􀀸 G/K30559/Jun08/CHY2H Areas outside the box will not be scanned for marking 7 Aluminium is a useful metal. 7 (a) The atomic number (proton number) of aluminium is 13. Complete the diagram to show the electronic structure of an aluminium atom. Use crosses (x) to represent the electrons. (1 mark) 7 (b) Aluminium is used as the electrical conductor for overhead power cables. Explain why metals are good conductors of electricity. ............................................................................................................................................ ............................................................................................................................................ ............................................................................................................................................ ............................................................................................................................................ (2 marks) ____ 3 (11)12 Areas outside the box will not be scanned for marking G/K30559/Jun08/CHY2H 8 Epoxyethane has the formula C2H4O. It is used to make antifreeze and some types of plastic. When choosing a method of making a chemical, it is important to consider: 􀁺 the percentage yield 􀁺 the atom economy. Epoxyethane can be made from ethene by two different methods. The overall equation for each method is shown below. Method 1 C2 H4 + Cl2 + Ca(OH)2 → C2H4O + CaCl2 + H2O ethene epoxyethane Method 2 catalyst 2C2H4(g) + O2(g) 2C2H4O(g) ethene epoxyethane 8 (a) The table gives the relative formula masses (Mr) of the reactants and products for Method 1. Formula of reactant or product Relative formula mass (Mr) H2O 18 C2H4 28 C2H4O 44 Cl2 71 Ca(OH)2 74 CaCl2 111 The percentage atom economy can be calculated using: Percentage atom economy = Mr of useful product × 100 % ________________________________ Total Mr of all reactants added together The percentage atom economy for Method 2 is 100 %. (12)13 G/K30559/Jun08/CHY2H Areas outside the box will not be scanned for marking 8 (a) Calculate the percentage atom economy for Method 1. ............................................................................................................................................ ............................................................................................................................................ ............................................................................................................................................ ............................................................................................................................................ (2 marks) 8 (b) Method 2 has the higher atom economy. Suggest why this is an advantage. ............................................................................................................................................ ............................................................................................................................................ ............................................................................................................................................ ............................................................................................................................................ (2 marks) 8 (c) State and explain how an increase in pressure would affect the equilibrium yield of epoxyethane using Method 2. ............................................................................................................................................ ............................................................................................................................................ ............................................................................................................................................ ............................................................................................................................................ (2 marks) 8 (d) One problem with Method 2 is that ethene can also react with oxygen to make carbon dioxide and water.C2H4 + 3O2 → 2CO2 + 2H2O How might this reaction affect the percentage yield of epoxyethane? ............................................................................................................................................ ............................................................................................................................................ (1 mark) ____ 7 END OF QUESTIONS (13)14 G/K30559/Jun08/CHY2H There are no questions printed on this page DO NOT WRITE ON THIS PAGE ANSWER IN THE SPACES PROVIDED (14)15 G/K30559/Jun08/CHY2H (15) There are no questions printed on this page DO NOT WRITE ON THIS PAGE ANSWER IN THE SPACES PROVIDED16 G/K30559/Jun08/CHY2H Copyright © 2008 AQA and its licensors. All rights reserved. (16) There are no questions printed on this page DO NOT WRITE ON THIS PAGE ANSWER IN THE SPACES PROVIDED ACKNOWLEDGEMENT OF COPYRIGHT-HOLDERS AND PUBLISHERS: Question 5 Photograph: © DEE LOVELLData Sheet 4421/63/DS 1. Reactivity Series of Metals 2. Formulae of Some Common Ions Positive ions Name Hydrogen Sodium Silver Potassium Lithium Ammonium Barium Calcium Copper(II) Magnesium Zinc Lead Iron(II) Iron(III) Aluminium H + Na + Ag + K + Li + NH4 + Ba 2+ Ca 2+ Cu 2+ Mg 2+ Zn 2+ Pb 2+ Fe 2+ Fe 3+ Al 3+ Chloride Bromide Fluoride Iodide Hydroxide Nitrate Oxide Sulfide Sulfate Carbonate Cl – Br – F – I – OH – NO3 – O 2– S 2– SO4 2– CO3 2– Formula June 2008 Insert for GCSE Additional Science (CHY2) and GCSE Chemistry (CHY3) Question Papers Turn over Name Formula Negative ions Potassium Sodium Calcium Magnesium Aluminium Carbon Zinc Iron Tin Lead Hydrogen Copper Silver Gold Platinum (elements in italics, though non-metals, have been included for comparison) most reactive least reactiveLi 73 lithium Na 23 11 sodium K39 19 potassium Rb 85 37 rubidium Cs 133 55 caesium Fr [223] 87 * The Lanthanides (atomic numbers 58 – 71) and the Actinides (atomic numbers 90 – 103) have been omitted. Cu and Cl have not been rounded to the nearest whole number. francium Be 1 2 Key 94 beryllium atomic symbol relative atomic mass atomic (proton) number name Mg 24 12 magnesium Ca 40 20 calcium Sr 88 38 strontium Ba 137 56 barium Ra [226] 88 radium Sc 45 21 scandium Y89 39 yttrium La* 139 57 lanthanum Ac* [227] 89 actinium Ti 48 22 titanium Zr 91 40 zirconium Hf 178 72 hafnium Rf [261] 104 rutherfordium V51 23 vanadium Nb 93 41 niobium Ta 181 73 tantalum Db [262] 105 dubnium Cr 52 24 chromium Mo 96 42 molybdenum W 184 74 tungsten Sg [266] 106 seaborgium Mn 55 25 manganese Tc [98] 43 technetium Re 186 75 rhenium Bh [264] 107 bohrium H 1 hydrogen Fe 56 26 1 iron Ru 101 44 ruthenium Os 190 76 osmium Hs [277] 108 hassium Co 59 27 cobalt Rh 103 45 rhodium Ir 192 77 iridium Mt [268] 109 meitnerium Ni 59 28 nickel Pd 106 46 palladium Pt 195 78 platinum Ds [271] 110 darmstadtium Cu 63.5 29 copper Ag 108 47 silver Au 197 79 gold Zn 65 30 zinc Cd 112 48 cadmium Hg 201 80 mercury B11 5 boron Al 27 13 aluminium Ga 70 31 gallium In 115 49 indium Tl 204 81 thallium C12 6 carbon Si 28 14 silicon Ge 73 32 germanium Sn 119 50 tin Pb 207 82 Elements with atomic numbers 112 – 116 have been reported but not fully authenticated lead N14 7 nitrogen P 31 15 phosphorus As 75 33 arsenic Sb 122 51 antimony Bi 209 83 bismuth O16 8 oxygen S 32 16 sulfur Se 79 34 selenium Te 128 52 tellurium Po [209] 84 polonium F 19 9 fluorine Cl 35.5 17 chlorine Br 80 35 bromine I 127 53 iodine At [210] 85 astatine Ne 3 4 5 6 7 0 20 10 neon He 42 helium Ar 40 18 argon Kr 84 36 krypton Xe 131 54 xenon Rn [222] 86 radon Rg [272] 111 roentgenium 3. The Periodic Table of Elements