Centre Number Surname Candidate Number For Examiner s Use Other Names Candidate Signature Examiner s Initials Question Mark AQA Level 1/2 Certificate June 2014 Chemistry 8402/2 Paper 2 Tuesday 10 June 2014 For this paper you must have: a ruler a calculator the periodic table (enclosed). 1.30 pm to 3.00 pm 1 2 3 4 5 6 7 TOTAL Time allowed 1 hour 30 minutes A Instructions Use black ink or black ball-point pen. Fill in the es at the top of this page. Answer all questions. You must answer the questions in the spaces provided. around each page or on blank pages. Do all rough work in this book. Cross through any work you do not want to be marked. Information The marks for questions are shown in brackets. The maximum mark for this paper is 90. You are expected to use a calculator where appropriate. You are reminded of the need for good English and clear presentation in your answers. Question 5(b) should be answered in continuous prose. In this question you will be marked on your ability to: use good English organise information clearly use specialist vocabulary where appropriate. Advice In all calculations, show clearly how you work out your answer. (Jun148402201) G/KL/101907/Jun14/E4 8402/2
2 Answer all questions in the spaces provided. 1 (a) Some metal carbonates break down when heated to produce carbon dioxide gas. The word equation for this reaction is: metal carbonate metal oxide + carbon dioxide 1 (a) (i) What name is given to a chemical reaction in which a compound breaks down when heated? Tick ( ) one. Exothermic Neutralisation Thermal decomposition 1 (a) (ii) What is the name of the metal oxide produced when calcium carbonate is heated? 1 (a) (iii) Limestone contains calcium carbonate. Draw a ring around the correct answer to complete the sentence. Limestone is obtained by distillation electrolysis quarrying 1 (a) (iv) Limestone is used in the extraction of iron. State one other use of limestone. (02)
3 1 (b) A student investigated the change in mass when metal carbonates are heated. 1 (b) (i) The equation for the reaction that takes place when copper carbonate is heated is: CuCO 3 (s) CuO(s) + CO 2 (g) Why is there a decrease in mass of the solid when copper carbonate is heated? Tick ( ) one. Carbon dioxide gas is given off. The copper carbonate expands when heated. There are two products. 1 (b) (ii) When potassium carbonate is heated there is no change in the mass of the solid. Suggest why. Question 1 continues on the next page Turn over (03)
4 1 (c) The student investigated the decomposition of metal carbonates using the apparatus shown in Figure 1. Figure 1 Rubber bung Water Metal carbonate Measuring cylinder HEAT The student measured the volume of gas collected after heating the metal carbonate for 5 minutes. 1 (c) (i) The student made a mistake in setting up the apparatus. The mistake would cause a systematic error. What mistake did the student make? (04)
5 1 (c) (ii) The student corrected the mistake he had made. Table 1 shows the student s results. Table 1 Metal carbonate Volume of gas collected in cm 3 Experiment 1 Experiment 2 Experiment 3 Magnesium carbonate 22 21 20 Iron carbonate 29 28 27 Rubidium carbonate 4 4 4 Zinc carbonate 24 22 0 One of the results in Table 1 is anomalous. Draw a ring around the anomalous result. Suggest what may have caused the anomalous result. 1 (c) (iii) The student tested the gases collected with limewater. The gas collected when rubidium carbonate was heated strongly did not turn limewater cloudy. Explain why. 11 Turn over (05)
6 2 A student was trying to produce hydrogen gas. Figure 2 shows the apparatus she used. Figure 2 Water Flask Dilute hydrochloric acid Copper 2 (a) No gas was produced. The student s teacher said that this was because the substances in the flask did not react. 2 (a) (i) Suggest why the substances in the flask did not react. 2 (a) (ii) Which two substances could the student have put in the flask to produce hydrogen safely? Tick ( ) one. Gold and dilute hydrochloric acid Potassium and dilute hydrochloric acid Zinc and dilute hydrochloric acid (06)
7 2 (b) Another student did produce hydrogen from two substances. Figure 3 shows the apparatus the student used to collect and measure the volume of the hydrogen gas. Figure 3 X 0 50 100 Give the name of the apparatus labelled X. Question 2 continues on the next page Turn over (07)
8 2 (c) The student did the experiment four times. Her results are shown in Table 2. Table 2 Experiment Volume of hydrogen collected in one minute in cm 3 1 49 2 50 3 35 4 48 2 (c) (i) One of the results is anomalous. Which result is anomalous? Write your answer in the. Give a reason for your choice. 2 (c) (ii) Calculate the mean volume of hydrogen collected in one minute. Mean volume =... cm 3 2 (c) (iii) Give a reason why the experiment should be repeated several times. (08)
9 2 (d) A teacher collected two tubes full of hydrogen gas, as shown in Figure 4. Figure 4 Hydrogen gas Tube A Tube B She tested tube A with a lighted splint as soon as she took the bung out. She tested tube B with a lighted splint a few seconds after taking the bung out. 2 (d) (i) Suggest why tube B gave a much louder pop than tube A. 2 (d) (ii) Complete and balance the chemical equation for the reaction that takes place when the hydrogen reacts in this test. H 2 + O 2 11 Turn over for the next question Turn over (09)
10 3 A student investigated displacement reactions of metals. The student added different metals to copper sulfate solution and measured the temperature change. The more reactive the metal is compared with copper, the bigger the temperature change. The apparatus the student used is shown in Figure 5. Figure 5 Thermometer Copper sulfate solution Metal 3 (a) State three variables that the student must control to make his investigation a fair test. [3 marks] 1.... 2.... 3... (10)
11 3 (b) Figure 6 shows the thermometer in one experiment before and after the student added a metal to the copper sulfate solution. Figure 6 Before adding metal After adding metal C 35 C 35 30 30 25 25 20 20 15 15 Use Figure 6 to complete Table 3. [3 marks] Table 3 Temperature before adding metal in C Temperature after adding metal in C Change in temperature in C......... Question 3 continues on the next page Turn over (11)
12 3 (c) The student repeated the experiment three times with each metal. Table 4 shows the mean temperature change for each metal. Table 4 Metal Mean temperature change in C Cobalt 4.5 Gold 0.0 Magnesium 10.0 Nickel 3.0 Silver 0.0 Tin 1.5 3 (c) (i) On Figure 7, draw a bar chart to show the results. [3 marks] Figure 7 10 8 Mean temperature change in C 6 4 2 0 (12)
13 3 (c) (ii) Why is a line graph not a suitable way of showing the results? 3 (c) (iii) Use the results to work out which metal is the most reactive. Give a reason for your answer. Most reactive metal... Reason... 3 (c) (iv) Explain why there was no temperature change when silver metal was added to the copper sulfate solution. 3 (c) (v) It is not possible to put all six metals in order of reactivity using these results. Suggest how you could change the experiment to be able to put all six metals into order of reactivity. 16 Turn over (13)
14 4 Iron will rust in damp air. 4 (a) Iron reacts with water and oxygen to produce rust. 4 (a) (i) As iron rusts there is a colour change. Draw a ring around the correct answer to complete the sentence. During the reaction iron changes from grey to blue brown green 4 (a) (ii) Rust is hydrated iron oxide. Write a word equation for the reaction of iron with oxygen and water. 4 (b) A student set up the apparatus shown in Figure 8. Figure 8 Iron wool Burette Air 10 20 50 40 30 0 Water The student left the apparatus for a few days. The water level in the burette slowly went up and then stopped rising. (14)
15 Figure 9 shows the water level in the burette at the start of the experiment and after a few days. Figure 9 At start After a few days 32 24 33 25 4 (b) (i) Complete Table 5 to show the reading on the burette after a few days. Table 5 Burette reading at start 24.7 cm 3 Burette reading after a few days...cm 3 4 (b) (ii) Calculate the volume of oxygen used up in the reaction. Volume =... cm 3 Question 4 continues on the next page Turn over (15)
16 4 (b) (iii) The percentage of air that is oxygen can be calculated using the equation: percentage of air that is oxygen = volume of oxygen used up volume of air at start 100 The student cannot use his results to calculate the correct percentage of air that is oxygen. Explain why. 4 (c) A student investigated the rusting of an iron nail at different temperatures. This is the method the student used: measure the mass of a nail set up apparatus as shown in Figure 10 leave for 3 days measure the mass of the rusted nail. Figure 10 Rubber bung Thread Nail Water The student repeated the experiment at different temperatures using a new, identical, nail each time. (16)
17 The student s results are shown on the graph in Figure 11. 0.20 Figure 11 0.15 Increase in mass of nail in g 0.10 0.05 0.00 0 10 20 30 40 50 60 70 80 Temperature in C 4 (c) (i) Why does the mass of the nail increase when it rusts? 4 (c) (ii) Use the graph to describe the relationship between the temperature and the increase in mass of the nail. [3 marks] Question 4 continues on the next page Turn over (17)
18 4 (c) (iii) The increase in mass of the nail after 3 days is a measure of the rate of rusting. The student s graph does not correctly show how increasing the temperature above 42 C changes the rate of rusting. How could the experiment be changed to show the effect of temperatures above 42 C on the rate of rusting? Give a reason for your answer. 12 (18)
19 5 This question is about copper. 5 (a) Most of the copper extracted is used in electric circuits. Figure 12 shows how impurities change the electrical conductivity of copper. Relative electrical conductivity 100 90 80 70 60 50 Figure 12 40 0.0 0.2 0.4 0.6 0.8 Percentage of impurities in copper 1.0 Copper extracted by smelting is about 99% pure. The 99% pure copper produced by smelting is purified to 99.9999% pure copper by electrolysis. Use values from the graph to explain why copper is purified to 99.9999%. Question 5 continues on the next page Turn over (19)
20 5 (b) In this question you will be assessed on using good English, organising information clearly and using specialist terms where appropriate. Read the information in the. Copper extraction World demand for copper for the year 2011 was about 20 million tonnes. World reserves of copper are estimated to be 700 million tonnes. Most of the copper used is obtained from copper ores, which are mined. The copper ore chalcopyrite is heated in a furnace to produce copper sulfide, CuS The furnace is heated by burning fossil fuels. Air is then blown through the hot copper sulfide, to produce copper and sulfur dioxide. CuS + O 2 Cu + SO 2 A scientist made the statement: Copper should be recycled. Use the information in the and your own knowledge and understanding to justify the scientist s statement. [6 marks] (20)
21 Extra space... 5 (c) Phytomining is used to obtain copper from land that contains very low percentages of copper compounds. Describe how copper compounds are obtained by phytomining. [3 marks] 11 Turn over (21)
22 6 Calcium chloride (CaCl 2 ) is a soluble salt. Calcium chloride can be made by reacting dilute hydrochloric acid with either solid calcium oxide or solid calcium carbonate. 6 (a) Name the type of reaction that takes place when dilute hydrochloric acid reacts with calcium oxide. 6 (b) Write a balanced symbol equation for the reaction of dilute hydrochloric acid with calcium oxide. 6 (c) A student added solid calcium oxide to dilute hydrochloric acid in a beaker. The student added solid calcium carbonate to dilute hydrochloric acid in another beaker. Describe one difference between the two reactions that the student would see. 6 (d) Describe how crystals of calcium chloride can be made from calcium carbonate and dilute hydrochloric acid. [4 marks] (22)
23 6 (e) A student dissolved some crystals of a salt in water. The student added sodium hydroxide solution to the salt solution. The student added sodium hydroxide solution until it was in excess. 6 (e) (i) Describe what the student would see if the salt contained calcium ions. 6 (e) (ii) Why does the result you have described in part (e)(i) not prove that the salt contains calcium ions? 6 (e) (iii) Describe an additional test the student could do that would prove the salt contains calcium ions. 13 Turn over for the next question Turn over (23)
24 7 (a) Ethanol (C 2 H 5 OH) is an alcohol. 7 (a) (i) Draw the displayed structure of ethanol. 7 (a) (ii) Complete combustion of ethanol produces carbon dioxide and water. Complete the balanced symbol equation for this reaction. [3 marks] C 2 H 5 OH +... 7 (a) (iii) Explain, in terms of bond breaking and bond forming, why the combustion of ethanol is exothermic. [3 marks] (24)
25 7 (b) A group of students investigated the amount of energy given out when different alcohols are burned. The students used the apparatus shown in Figure 13. Figure 13 Thermometer Calorimeter 50 g of water Alcohol In one experiment the temperature of 50 g of water increased from 22.5 C to 38.3 C. The mass of alcohol burned was 0.85 g. 7 (b) (i) The energy used to heat the water, Q, can be found using the equation: Q = m c T Calculate the heat energy, in joules, given out by burning 0.85 g of the alcohol. Assume that all of the heat energy given out by burning the alcohol is used to heat the water (specific heat capacity of water = 4.2 J / g / C). Heat energy =... J 7 (b) (ii) Use your answer to part (b)(i) and the fact that 0.85 g of alcohol were burned to calculate the heat energy that would be given out by 1 g of alcohol. If you could not answer part (b)(i), use 3000 J as the heat energy given out by burning 0.85 g of the alcohol. This is not the correct answer to part (b)(i). Heat energy =... J Turn over (25)
26 7 (c) Another group of students investigated the amount of heat energy given out when different alcohols are burned. They used a different, better, set of apparatus than the first group of students. They used the results from their investigation to calculate the heat energy given out by burning 1 g of each alcohol. They used a data book to find the theoretical amount of heat energy 1 g of each alcohol should have given out when burned completely. The students recorded their experimental results and the theoretical values in Table 6. Table 6 Name of alcohol Number of carbon atoms in one molecule of alcohol Experimental amount of heat energy given out when 1 g is burned in kj Theoretical amount of heat energy given out when 1 g is burned completely in kj Methanol 1 11.4 22.7 Ethanol 2 14.5 29.7 Propanol 3 16.0 33.7 Butanol 4 16.8 36.2 Pentanol 5 17.2 37.8 Hexanol 6 17.4 39.1 7 (c) (i) What is the relationship between the number of carbon atoms in one molecule of the alcohol and the heat energy given out when the alcohol is burned? (26)
27 7 (c) (ii) Suggest one reason why the students experimental results are lower than the theoretical values. 7 (c) (iii) The students observed that as the number of carbon atoms in one molecule of the alcohol increased: the flame was more orange more carbon was left on the bottom of the calorimeter. Suggest why. 7 (c) (iv) The heat energy given out when 1 g of ethanol (C 2 H 5 OH) is burned is 29.7 kj. Calculate the heat energy, in kilojoules, that will be given out when 1 mole of ethanol is burned. Give your answer to three significant figures. Relative atomic masses: H = 1; C = 12; O = 16 [3 marks] Heat energy =... kj 16 END OF QUESTIONS (27)
28 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 Permission to reproduce all copyright material has been applied for. In some cases, efforts to contact copyright-holders have been unsuccessful and AQA will be happy to rectify any omissions of acknowledgements in future papers if notified. Copyright 2014 AQA and its licensors. All rights reserved. (28)