SPECIMEN GATEWAY SCIENCE B742/02 CHEMISTRY B GENERAL CERTIFICATE OF SECONDARY EDUCATION. Duration: 1 hour 30 minutes. Candidate Forename

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1 SPECIMEN H GENERAL CERTIFICATE OF SECONDARY EDUCATION GATEWAY SCIENCE B742/02 CHEMISTRY B Unit B742: Chemistry modules C4, C5, C6 (Higher Tier) Candidates answer on the question paper A calculator may be used for this paper OCR Supplied Materials: None Duration: 1 hour 30 minutes Other Materials Required: Pencil Ruler (cm/mm) Candidate Forename Candidate Surname Centre Number Candidate Number INSTRUCTIONS TO CANDIDATES Write your name clearly in capital letters, your Centre Number and Candidate Number in the boxes above. Use black ink. Pencil may be used for graphs and diagrams only. Read each question carefully and make sure that you know what you have to do before starting your answer. Answer all the questions. Write your answer to each question in the space provided, however additional paper may be used if necessary but you must clearly show your candidate number, centre number and question number(s). Do not write in the bar codes. INFORMATION FOR CANDIDATES Your quality of written communication is assessed in questions marked with a pencil ( ). The number of marks for each question is given in brackets [ ] at the end of the question or part question. The total number of marks for this paper is 85. This document consists of 23 pages. Any blank pages are indicated. Examiner s Use Only Total OCR 2012 [QN 01/SPEC/X] OCR is an exempt Charity Turn over

2 2 Answer all the questions. Section A Module C4 1 Francium, Fr, is in Group 1 of the Periodic Table. It has an atomic number of 87. (a) An isotope of francium has a mass number of 223. Look at the table of information about this isotope. Complete the table. Number of electrons Number of protons Number of neutrons Number of electrons in outer shell Number of occupied shells [4] (b) Look at the table of melting and boiling points of the elements in Group 1. Element Melting point in o C Boiling point in o C lithium sodium potassium rubidium caesium francium The values for francium are not included because they are difficult to measure. (i) Which element has the strongest metallic bonds?... [1]

3 3 (ii) Room temperature is 20 o C. Predict the state of matter of francium at room temperature. Choose from solid, liquid or gas. answer. Explain your answer [1] (c) Francium reacts with water. Predict what you would see during the reaction [2] [Total: 8] Turn over

4 2 The table shows information about some metals. metal Melting point in o C Relative strength 4 Relative flexibility (very flexible = 10 and not flexible = 1 Corrosion iron rusts easily zinc steel corrodes slowly rusts very slowly Look at the diagram of a cable car used to travel across the River Thames. (a) A thick metal wire is used to hold up the cable car. Evaluate the suitability of each metal to make the thick metal wire. Which metal would you use?...[3] (b) All three metals are good conductors of electricity. Write about how metals conduct electricity....[2] [Total: 5]

5 3 Sodium, Na, reacts with chlorine, Cl 2, to make sodium chloride, NaCl. 5 Sodium chloride contains the ions Na + and Cl - Describe the structure of solid sodium chloride and explain why it has a high melting point and does not conduct electricity. The quality of written communication will be assessed in your answer to this question....[6] [Total: 6] Turn over

6 6 4 Precipitation reactions are often used to identify ions in solutions. (a) Barium chloride, BaCl 2, is used to identify sulfate ions. Barium chloride solution reacts with sodium sulfate solution, Na 2 SO 4. A white barium sulfate, BaSO 4, precipitate is formed. Construct the balanced symbol equation for this reaction.... [2] (b) Sodium hydroxide solution contains OH -. Copper (II) sulfate solution contains Cu 2+. These two ions make copper (II) hydroxide as a precipitate. Construct the balanced ionic equation for this reaction.... [2] 5 Carbon dioxide and phosphine both have a simple molecular structure. Predict two physical properties of phosphine. [Total: 4]...[2] [Total: 2]

7 7 6 Jeff is heating some copper carbonate. Section B Module C5 copper carbonate copper carbonate copper oxide + carbon dioxide Jeff does the experiment three times with different masses of copper carbonate. Look at his table of results. Mass of copper carbonate used in g heat Mass of copper oxide made in g Mass of carbon dioxide made in g (a) Predict the masses of copper oxide and carbon dioxide made when 4.00g of copper carbonate is heated. Write your answers in the table. [2] (b) In another experiment Jeff finds that 2.00g of copper carbonate contains 1.03g of copper. Calculate the percentage by mass of copper in copper carbonate. answer... % [2] (c) In a third experiment Jeff uses a compound called benzene. The molecular formula for benzene is C 6 H 6. What is the empirical formula for benzene?...[1] [Total: 5] Turn over

8 8 7 Adam is neutralising dilute hydrochloric acid with potassium hydroxide solution. He does a titration. burette potassium hydroxide solution datalogger 20.0 cm 3 of dilute hydrochloric acid ph probe Adam measures the ph of the solution as he adds the potassium hydroxide solution, KOH, to the dilute hydrochloric acid, HCl. Look at the graph of his results.

9 9 (a) What is the volume of potassium hydroxide solution added at neutralisation? answer... cm 3. [1] (b) Look at the equation for the reaction. KOH + HCl KCl + H 2 O In a second experiment, Adam finds that 20cm 3 of potassium hydroxide solution of concentration 0.1 mol/dm 3 react exactly with 25cm 3 of dilute hydrochloric acid. Calculate the concentration of the dilute hydrochloric acid in mol/dm 3. answer... mol/dm 3. [2] (c) Adam used a single indicator called litmus in his titration. Describe the difference between using a single indicator rather than a mixed indicator like universal indicator [2] (d) Adam is a scientist. He works as part of a team of scientists. Explain why it is better for scientists to work in teams rather than on their own [2] [Total: 7] Turn over

10 10 8 This question is about precipitation. (a) Ben and Sally test an unknown solution. Look at their results. Addition of lead nitrate solution yellow precipitate Addition of barium chloride solution white precipitate Ben thinks that the unknown solution contains both bromide ions, Br - and chloride ions, Cl -. Sally says that it contains iodide ions, I - and sulfate ions, SO Who is correct? Explain your answer [2] (b) Ben and Sally want to make a pure dry sample of insoluble lead chloride. They use lead nitrate solution and sodium chloride solution. Describe how they can make a pure, dry sample of lead chloride....[3] (c) During this reaction, lead ions, Pb 2+, react with chloride ions, Cl -. Lead chloride, PbCl 2, is made. Write the ionic equation for this reaction. Include state symbols....[2] [Total: 7]

11 11 9 This question is about a reversible reaction. Look at the equation. N 2(g) + 3H 2(g) 2NH 3(g) nitrogen + hydrogen ammonia The forward reaction is exothermic. Predict what effect increasing the temperature, pressure and the amount of nitrogen in the mixture will have on the position of equilibrium, explaining in detail in your answer. The quality of written communication will be assessed in your answer to this question....[6] [Total: 6] Turn over

12 12 10 This question is about fats and oils. SECTION C Module C6 (a) Look at the table of information about fats and oils. Substance Melting point in o C Boiling point in o C Effect on bromine water A B C D E Remains orange Goes colourless Remains orange Remains orange Goes colourless Which substances are saturated fats or oils? Explain your answer [2] (b) Look at the displayed formula. It shows part of the molecule of a fat. (i) How can you tell that the fat is unsaturated? [1] (ii) This fat can be changed into margarine. Describe how [1]

13 13 (c) Fats can be hydrolysed by reacting with hot sodium hydroxide solution. Soap and compound A are made. Look at the displayed formula for compound A. What is the molecular formula for compound A? compound A [1] [Total: 5] Turn over

14 14 11 Gill and Repa have three different samples of water. The samples are from different areas of the country. Gill and Repa know that water from different parts of the country may have different amounts of hardness. They investigate the amount of hardness in each sample. The diagram shows some of the apparatus that Gill and Repa use. (a) Plan an experiment to compare the hardness of the three different samples. Use the apparatus in the diagram [2]

15 15 (b) Temporary hard water contains calcium hydrogencarbonate Temporary hardness can be removed by boiling the water. The calcium hydrogencarbonate decomposes. Calcium carbonate, carbon dioxide and water are made. Write the balanced symbol equation for this reaction.... [1] (c) Gill tells Repa that another way to remove hardness from water is to use an ion exchange resin. How does an ion exchange resin remove hardness from water?... [2] [Total: 5] Turn over

16 16 12 The diagram shows the apparatus used during the electrolysis of molten (liquid) lead bromide, PbBr 2. (a) Lead bromide can be electrolysed when it is molten (a liquid). Lead bromide cannot be electrolysed when it is a solid. Explain why....[2] (b) During the electrolysis the lead ions, Pb 2+, gain electrons to make lead atoms, Pb. Write the balanced equation for this reaction. Use e - to represent an electron.... [2]

17 17 (c) A teacher electrolyses molten lead bromide. He measures the mass of lead produced in four different experiments. Look at the table of results. Experiment number Time of electrolysis in seconds Current used in electrolysis in amps Mass of lead deposited at the cathode in grams (i) How do these results show that the mass of lead made during electrolysis is directly proportional to both the time of electrolysis and the current used? [2] (ii) Complete the table to show the time in seconds for experiment 4. [1] [Total: 7] Turn over

18 18 13 Neil has a stain on his coat. He thinks that the stain might be grease. He takes his coat to the dry cleaners. Describe what is meant by dry cleaning. Explain how dry cleaning will remove the grease from Neil s clothes. The quality of written communication will be assessed in your answer to this question....[6] [Total: 6]

19 19 14 This question is about sacrificial protection. Look at this order of reactivity. Most reactive Least reactive magnesium zinc iron tin copper Phil decides to protect the steel hull of his boat using a block of copper. He knows that steel is mostly iron. The block of copper does not provide sacrificial protection. Explain why and suggest what might happen to the steel hull.... [2] [Total: 2] Turn over

20 20 Section D 15 This question is about some of the gases in the air. Scientists are concerned about the increase in air pollution. (a) Many scientists think that carbon dioxide may affect the chemistry of the oceans. They know that carbon dioxide reacts with water to make an acid. carbon dioxide + water carbonic acid Look at the graph. It shows the percentage of carbon dioxide between 1970 and percentage of carbon dioxide in the air (%) year Look at the table. It shows the ph of the oceans between 1970 and Year ph of the ocean (i) What was the percentage of carbon dioxide in the air in 1994? % [1]

21 (ii) Draw a conclusion about the effect of carbon dioxide on the oceans? [1] (iii) Plot the data from the table in a graph. Use the graph to estimate what the ph of the oceans will be in ph of sea water year ph = [3] (b) Water vapour is a greenhouse gas. Greenhouse gases cause global warming. On some days the water vapour is responsible for 72% of the total greenhouse gas effect. On other days it is only 30%. Suggest a reason for this difference....[1] Turn over

22 22 (c) Each different greenhouse gas molecule has a GWP (global warming potential) value. The higher the GWP value the more global warming a molecule of that gas can cause. The GWP value of a gas depends on different factors; the ability of the gas to absorb infra-red radiation the atmospheric lifetime of the gas. Look at the table about gases and their GWP values. Gas Lifetime of gas in atmosphere in years GWP Percentage of gas in the atmosphere CCl 2 F very small CF very small CH CO N 2 O very small SF very small (i) Suggest why CCl 2 F 2 has a higher GWP than N 2 O....[1] (ii) The atmospheric concentrations of both CH 4 and CO 2 are both increasing. Evaluate the effect of both of these gases on a possible increase in global warming....[3] END OF QUESTION PAPER [Total: 10]

23 23 The Periodic Table of the Elements Li lithium 3 9 Be beryllium 4 Key relative atomic mass atomic symbol name atomic (proton) number 1 H hydrogen 1 11 B boron 5 12 C carbon 6 14 N nitrogen 7 16 O oxygen 8 19 F fluorine 9 4 He helium 2 20 Ne neon Na sodium Mg magnesium Al aluminium Si silicon P phosphorus S sulfur Cl chlorine Ar argon K potassium Ca calcium Sc scandium Ti titanium V vanadium Cr chromium Mn manganese Fe iron Co cobalt Ni nickel Cu copper Zn zinc Ga gallium Ge germanium As arsenic Se selenium Br bromine Kr krypton Rb rubidium Sr strontium Y yttrium Zr zirconium Nb niobium Mo molybdenum 42 [98] Tc technetium Ru ruthenium Rh rhodium Pd palladium Ag silver Cd cadmium In indium Sn tin Sb antimony Te tellurium I iodine Xe xenon Cs caesium Ba barium La* lanthanum Hf hafnium Ta tantalum W tungsten Re rhenium Os osmium Ir iridium Pt platinum Au gold Hg mercury Tl thallium Pb lead Bi bismuth 83 [209] Po polonium 84 [210] At astatine 85 [222] Rn radon 86 [223] Fr francium 87 [226] Ra radium 88 [227] Ac* actinium 89 [261] Rf rutherfordium 104 [262] Db dubnium 105 [266] Sg seaborgium 106 [264] Bh bohrium 107 [277] Hs hassium 108 [268] Mt meitnerium 109 [271] Ds darmstadtium 110 [272] Rg roentgenium 111 Elements with atomic numbers have been reported but not fully authenticated * The lanthanoids (atomic numbers 58-71) and the actinoids (atomic numbers ) have been omitted. The relative atomic masses of copper and chlorine have not been rounded to the nearest whole number.