Cambridge IGCSE Sciences - Co-ordinated (Double) 0654 — 2015 Oct/Nov Paper 5 · Variant 1

This document consists of 12 printed pages. IB15 11_0654_51/3RP © UCLES 2015 [Turn over *7933674268* For Examiner's Use 1 2 3 Total Cambridge International Examinations Cambridge International General Certificate of Secondary Education CO-ORDINATED SCIENCES 0654/51 Paper 5 Practical Test October/November 2015 2 hours Candidates answer on the Question Paper. Additional Materials: As listed in the Confidential Instructions. READ THESE INSTRUCTIONS FIRST Write your Centre number, candidate number and name on all the work you hand in. Write in dark blue or black pen. You may use an HB pencil for any diagrams or graphs. Do not use staples, paper clips, glue or correction fluid. DO NOT WRITE IN ANY BARCODES. Answer all questions. Electronic calculators may be used. You may lose marks if you do not show your working or if you do not use appropriate units. Notes for Use in Qualitative Analysis for this paper are printed on page 12. At the end of the examination, fasten all your work securely together. The number of marks is given in brackets [ ] at the end of each question or part question.

2 © UCLES 2015 0654/51/O/N/15 1 You are going to investigate what happens when food is burned in air. (a) (i) • Using the forceps, pick up a piece of dry cobalt chloride paper. Cobalt chloride paper changes colour from blue to pale pink or white in the presence of water. • Remove the stopper from one of the large test-tubes provided and place the piece of blue cobalt chloride paper inside. • Wait five seconds and then record the colour of the cobalt chloride paper. [1] • Remove the cobalt chloride paper from the test-tube. (ii) • Add 10 cm3 limewater to the same test-tube used in part (i). Replace the stopper and shake gently for 10 seconds. Describe the appearance of the limewater. [1] (b) • Remove the stopper from the second test-tube and grip it with the test-tube holder as shown in Fig. 1.1. mounted needle food test tube holder Fig. 1.1 • Place the piece of food provided on the mounted needle. • Using a Bunsen burner, ignite the piece of food. Move the Bunsen burner to one side. Collect any gases produced by holding the second large test-tube inverted about 2 cm above the flame produced as shown in Fig. 1.1. • Wait until the sides of the test-tube mist up and then place the food into the beaker of water to extinguish it. • Replace the stopper on the test-tube.

3 © UCLES 2015 0654/51/O/N/15 [Turn over Place a fresh piece of blue cobalt chloride paper into the test-tube and quickly replace the stopper. (i) Wait five seconds and then describe and explain the appearance of the cobalt chloride paper. appearance explanation [1] (ii) Remove the piece of cobalt chloride paper and quickly add about 10 cm3 limewater to the test-tube. Replace the stopper and shake the test-tube for 10 seconds. Describe the appearance of the limewater. [1] Explain your observation. [1] (c) State two observations of this experiment that show energy is released. [2] (d) State the purpose of the tests in part (a). [1] (e) (i) In this experiment you burned some food in air. Name the process inside living cells that this procedure is modelling. [1] (ii) Use the results from part (b) and your knowledge to give the word equation for this process. [2] (f) State one precaution you took to make sure that the procedure in part (b) was carried out safely. [1]

4 © UCLES 2015 0654/51/O/N/15 (g) A student carried out a similar procedure to measure the energy content of different foods by measuring the temperature increase of water. The apparatus is shown in Fig. 1.2. thermometer water burning food sample Fig. 1.2 (i) State two ways in which the student could make sure that this procedure is a fair comparison between different foods. [2] (ii) State why this procedure would not be suitable for accurately measuring the total energy content of food. [1]

5 © UCLES 2015 0654/51/O/N/15 [Turn over Please turn over for Question 2.

6 © UCLES 2015 0654/51/O/N/15 2 Potassium iodide can be converted to iodine by an oxidising agent. The presence of starch produces a blue-black colour when the iodine is formed. The time for the blue-black colour to appear depends on the rate of the reaction between potassium iodide and the oxidising agent. You are going to investigate whether certain metal ions can catalyse this reaction. You will also identify the metal ion X2+. A is potassium iodide solution. B is a solution of the oxidising agent. (a) (i) • Using the measuring cylinder labelled B, place 10 cm3 of B in a conical flask or beaker. • Add five drops of starch to the flask. • Using a second measuring cylinder labelled A, add 10 cm3 of A to the flask and swirl once, starting the stopclock at the same time. • Stop the stopclock when the solution turns blue-black. Record the time t in seconds to the nearest second in the second row of Table 2.1. [1] Table 2.1 volume of B / cm3 drops of starch volume of A / cm3 1 cm3 of solution of metal ion time t / s t 1 / s 1 10.0 5 10.0 none added 10.0 5 10.0 none added 10.0 5 10.0 Fe2+ 10.0 5 10.0 Fe3+ 10.0 5 10.0 X2+ (ii) Repeat (a)(i) and record the time t in seconds to the nearest second in the next row of Table 2.1. [2] (b) (i) • Using the measuring cylinder labelled B, place 10 cm3 of B in a conical flask or beaker. • Add five drops of starch to the flask. • Using the measuring cylinder labelled C add 1 cm3 of the solution containing the Fe2+ ion to the flask. • Using the measuring cylinder labelled A, add 10 cm3 of A to the flask and swirl once, starting the stopclock at the same time. • Stop the stopclock when the solution turns blue-black. Record the time t in seconds to the nearest second in the appropriate row of Table 2.1. [1]

7 © UCLES 2015 0654/51/O/N/15 [Turn over (ii) Repeat (b)(i), replacing the solution containing the Fe2+ ion with the solution containing the Fe3+ ion. Record the time t in seconds to the nearest second in the appropriate row of Table 2.1. [1] (iii) Repeat (b)(i), replacing the solution containing the Fe2+ ion with the solution containing the X2+ ion. Record the time t in seconds to the nearest second in the appropriate row of Table 2.1. [1] (c) (i) Calculate the values of t 1 for each reading of time t. Enter the values in Table 2.1. These represent the rates of the reaction. [1] (ii) Using your results in Table 2.1, state and explain whether the metal ions are acting as catalysts for this reaction. [2] (d) Use the two results obtained when no metal ion was added to comment on the reliability of the experiment. You must show how you use these two results. [1]

8 © UCLES 2015 0654/51/O/N/15 (e) (i) The addition of the metal ion in (b) increases the total volume of the solution in the experiment. Suggest a modification to the method in (a)(i) which would result in the overall experiment being a fairer test. Explain why you have chosen this modification. [2] (ii) A student suggests that the reaction involving the solution containing the X2+ ion is a completely different reaction and that X2+ ions reacts with iodide ions. Carry out (b)(iii) again using the solution containing the X2+ ion but carefully observe the reaction mixture instead of timing the reaction. Suggest what observations may have led the student to think that this was a different reaction. [1] (f) Use ammonia solution to identify metal X in the solution containing the X2+ ion. Record your observations. observations metal X is [2]

9 © UCLES 2015 0654/51/O/N/15 [Turn over 3 You are going to measure the capacity and the outer surface area of the walls of a plastic cup. (a) The capacity of a cup is the maximum volume of liquid that it can hold. The volume will be estimated by finding the average diameter of the cup and then considering the cup to be an approximate cylinder. (i) Measure, to the nearest 0.1 cm, the height h of the cup as shown in Fig. 3.1. D h d Fig. 3.1 h = cm (ii) Measure the diameter D of the top of the cup. D = cm (iii) Measure the diameter d of the bottom of the cup. d = cm (iv) Calculate the average diameter dA using your results from (a)(ii) and (a)(iii) and the equation dA = 2 d) (D + dA = cm (v) Calculate the approximate volume V of the cup using the equation V = 4 h d 2 A π V = cm3 [6]

10 © UCLES 2015 0654/51/O/N/15 (b) (i) Fill the measuring cylinder with water up to a mark in excess of 200 cm3. Record this reading R1. R1 = cm3 Pour water from the measuring cylinder into the cup until it is full. Record the new reading R2. R2 = cm3 Determine the volume of water VW that the cup can hold. Show your working. VW = cm3 [2] (ii) Suggest one possible source of inaccuracy in this procedure. [1] (iii) State which of the two values, V obtained in (a)(v) or VW obtained in (b)(i) is the more accurate. Explain your answer. [1]

11 © UCLES 2015 0654/51/O/N/15 (c) Empty the water from the cup. Use the string and the metre rule provided to determine the average circumference C of the cup. (i) Describe the method that you used and show your working. C = cm [3] Fig. 3.2 (ii) Show on Fig. 3.2 where you placed the string to measure the average circumference. [1] (iii) Calculate the approximate curved surface area A of the cup using the equation A = Ch A = cm2 [1]

12 Permission to reproduce items where third-party owned material protected by copyright is included has been sought and cleared where possible. Every reasonable effort has been made by the publisher (UCLES) to trace copyright holders, but if any items requiring clearance have unwittingly been included, the publisher will be pleased to make amends at the earliest possible opportunity. To avoid the issue of disclosure of answer-related information to candidates, all copyright acknowledgements are reproduced online in the Cambridge International Examinations Copyright Acknowledgements Booklet. This is produced for each series of examinations and is freely available to download at www.cie.org.uk after the live examination series. Cambridge International Examinations is part of the Cambridge Assessment Group. Cambridge Assessment is the brand name of University of Cambridge Local Examinations Syndicate (UCLES), which is itself a department of the University of Cambridge. © UCLES 2015 0654/51/O/N/15 NOTES FOR USE IN QUALITATIVE ANALYSIS Test for anions anion test test result carbonate (CO3 2-) add dilute acid effervescence, carbon dioxide produced chloride (Cl -) [in solution] acidify with dilute nitric acid, then add aqueous silver nitrate white ppt. nitrate (NO3 -) [in solution] add aqueous sodium hydroxide then aluminium foil; warm carefully ammonia produced sulfate (SO4 2-) [in solution] acidify then add aqueous barium chloride or aqueous barium nitrate white ppt. Test for aqueous cations cation effect of aqueous sodium hydroxide effect of aqueous ammonia ammonium (NH4 +) ammonia produced on warming - copper(II) (Cu2+) light blue ppt., insoluble in excess light blue ppt., soluble in excess giving a dark blue solution iron(II) (Fe2+) green ppt., insoluble in excess green ppt., insoluble in excess iron(III) (Fe3+) red-brown ppt., insoluble in excess red-brown ppt., insoluble in excess zinc (Zn2+) white ppt., soluble in excess giving a colourless solution white ppt., soluble in excess giving a colourless solution Test for gases gas test and test results ammonia (NH3) turns damp red litmus paper blue carbon dioxide (CO2) turns limewater milky chlorine (Cl2) bleaches damp litmus paper hydrogen (H2) “pops” with a lighted splint oxygen (O2) relights a glowing splint

® IGCSE is the registered trademark of Cambridge International Examinations. CAMBRIDGE INTERNATIONAL EXAMINATIONS Cambridge International General Certificate of Secondary Education MARK SCHEME for the October/November 2015 series 0654 CO-ORDINATED SCIENCES 0654/51 Paper 5 (Practical), maximum raw mark 45 This mark scheme is published as an aid to teachers and candidates, to indicate the requirements of the examination. It shows the basis on which Examiners were instructed to award marks. It does not indicate the details of the discussions that took place at an Examiners’ meeting before marking began, which would have considered the acceptability of alternative answers. Mark schemes should be read in conjunction with the question paper and the Principal Examiner Report for Teachers. Cambridge will not enter into discussions about these mark schemes. Cambridge is publishing the mark schemes for the October/November 2015 series for most Cambridge IGCSE®, Cambridge International A and AS Level components and some Cambridge O Level components.

Page 2 Mark Scheme Syllabus Paper Cambridge IGCSE – October/November 2015 0654 51 © Cambridge International Examinations 2015 1 (a) (i) (any) blue / no change ; [1] (ii) colourless / like water / clear ; [1] (ignore: stayed the same) (b) (i) turns white / pink AND indicates water is produced / present ; [1] (ii) turns milky / cloudy / white ppt. ; (allow: murky) (indicates) carbon dioxide / CO2 ; [2] (c) heat produced / temperature increase ; light produced / glows / fire / flame / smoke ; [2] (d) a control / show that water not already present / show that carbon dioxide not already present ; [1] (e) (i) respiration ; [1] (ii) glucose / food / cheese + oxygen (not air) → carbon dioxide + water LHS correct = 1 ; RHS correct = 1 ; [2] (f) goggles / hair tied back / Bunsen at safe distance / keep maximum distance from burning food / accept other sensible suggestions ; [1] (ignore: test-tube holders as in diagram) (g) (i) same mass of water / same volume of water / same amount of water ; same distance to test-tube ; same volume of water ; same start temperature of water ; same mass of food ; [max 2] (ignore: same time of burning) (ii) heat loss / incomplete burning ; [1] [Total: 15]

Page 3 Mark Scheme Syllabus Paper Cambridge IGCSE – October/November 2015 0654 51 © Cambridge International Examinations 2015 2 (a) (i) value of time greater than or equal to 10 s ; [1] (allow: answers in minutes and seconds) (ii) value within 10% of first value ; both values to nearest second ; [2] (b) (i) Fe2+ value less than both values in (a) ; [1] (ii) Fe3+ value less than both values in (a), AND to nearest second ; [1] (iii) X2+ value less than or equal to 5 s / X2+ value is ‘instant’ ; [1] (c) (i) at least four t 1 values calculated correctly (ignore s.f.) ; [1] (if t = 0 allow t 1 to be left blank or infinity but do not allow zero) (ii) they are catalysts ; t 1 (rate) increased (with addition of metal ion) / time decreased (with addition of metal ion) ; [2] (d) reliable as within 10% (or other suitable percentage or comment) OR not reliable as greater than 10% difference (or other suitable percentage or comment) ; [1] (answer must demonstrate an understanding of reliability) (ignore: references to accuracy) (e) (i) add 1 cm3 water / add 5 drops + 1 cm3 starch ; (do NOT allow: 0.5 cm3 more of A and 0.5 cm3 more of B) total volume should be same as in (b) / equivalent volume to metal ion / to keep concentrations the same ; [2] (mark independently) (ii) ppt. / white ppt. / cream ppt. / instant blue-black / instant reaction / more brown ; [1] (f) blue ppt. / dark blue solution ; X is copper / Cu (depends on blue in first marking point) ; [2] (allow: Cu2+ or copper(II) for second marking point) [Total: 15]

Page 4 Mark Scheme Syllabus Paper Cambridge IGCSE – October/November 2015 0654 51 © Cambridge International Examinations 2015 3 (a) h AND D AND d recorded ; h > D > d ; all values to the nearest 0.1 cm ; dA calculation correct ; V calculation correct ; V given as whole number ; [6] (b) (i) Vw correctly calculated with working shown, e.g. subtraction of two values ; Vw is supervisor’s value ± 20 cm3 (can get this accuracy mark without calculation) ; [2] (ii) cup not completely full / measuring cylinder not read at eye level / measuring cylinder not read perpendicularly / measuring cylinder not read from bottom of meniscus / water spilled on transfer / R2 off scale of measuring cylinder ; [max 1] (iii) VW since difficult to measure h / VW since d (or D) not inside diameters / VW since it is a direct measurement / VW since V is an approximation / VW is actual measurement whereas V uses a formula ; [max 1] (c) (i) evidence of at least 2 loops of string around cup ; (this could be in words or from diagram and could be in different positions or one position repeated) correct averaging of two or more measurements for value of C ; answer to 0.1 cm (independent mark) ; [3] (ii) diagram showing correct positioning of one loop, e.g. half way up / at top / at bottom ; [1] (iiii) calculation correct to 2 or 3 s.f. ; [1] [Total: 15]