Cambridge IGCSE Science - Combined 0653 — 2012 May/June Paper 5 · Variant 2

This document consists of 10 printed pages and 2 blank pages. IB12 06_0653_52/2RP © UCLES 2012 [Turn over *5821529513* For Examiner's Use 1 2 3 Total UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS International General Certificate of Secondary Education COMBINED SCIENCE 0653/52 Paper 5 Practical Test May/June 2012 1 hour 30 minutes Candidates answer on the Question Paper. Additional Materials: As listed in Instructions to Supervisors. 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 a pencil for any diagrams, graphs or rough working. Do not use staples, paper clips, highlighters, glue or correction fluid. DO NOT WRITE IN ANY BARCODES. Answer all questions. Chemistry practical notes 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. www.XtremePapers.com

2 © UCLES 2012 0653/52/M/J/12 For Examiner's Use 1 You are going to investigate the digestion of fat in milk by the action of the enzyme lipase. (a) ● Half fill a 500 cm3 beaker with the hot and cold water provided to make a water bath with a temperature between 35 °C and 40 °C. It may be necessary to add more hot water to maintain this temperature range. • Using a measuring cylinder, place 7 cm3 of sodium carbonate solution into each of tubes A and B. • Using a measuring cylinder, place 5 cm3 of full fat milk into each of tubes A and B. • Place 5 drops of phenolphthalein indicator solution into each of tubes A and B. • Place both tubes into the water bath and leave them for 10 minutes, remembering to maintain the temperature range as above. During this 10 minutes continue with part (e). • After 10 minutes, using a syringe, add 1 cm3 boiled lipase solution to tube A and mix. Immediately, using a syringe, add 1 cm3 of unboiled lipase to tube B and mix. Leave both tubes in the water bath. • Start the timer. • Record in Table 1.1 the time taken, in seconds, for the pink colour of the mixtures to disappear. If no colour change has occurred after 10 minutes, record ‘no change’. Table 1.1 tube A B lipase boiled unboiled time taken for pink colour to disappear / s [3] (b) Lipase breaks down fat into fatty acids. Sodium carbonate is a weak alkali. Phenolphthalein is an indicator. If the solution has a pH of above 8, it is pink. If the pH is less than 8, it is colourless. If any of the solutions turned from pink to colourless, suggest and explain why the solution changed colour. [2]

3 © UCLES 2012 0653/52/M/J/12 [Turn over For Examiner's Use (c) Suggest and explain how the results indicate that lipase is an enzyme. [2] (d) Suggest one source of error in the experiment. [1] (e) ● Using a measuring cylinder, place 5 cm3 of fresh full fat milk into tube C. • Using a measuring cylinder, place 5 cm3 of biuret reagent into tube C and mix. Record in Table 1.2 the colour of the resulting solution and suggest a reason for the colour. Table 1.2 tube C colour of solution reason for colour [2]

4 © UCLES 2012 0653/52/M/J/12 For Examiner's Use 2 You are going to find the density of a material used to make plastic pipes. You will use two different methods to find the volume of the piece of pipe. (a) (i) Use the balance provided to find the mass in grams, M, of your piece of plastic pipe. Record your answer to 1 decimal place. M = g [1] l side view de di end view plastic pipe plastic pipe Fig. 2.1 (ii) Method 1 Measure the length, l, the external diameter, de, and the internal diameter, di, in centimetres as shown in Fig. 2.1, of your piece of plastic pipe. Record your measurements below. length, l = external diameter, de = internal diameter, di = [1] (iii) Use your values of external and internal diameters, in cm, to calculate k from the formula below. k = de 2 – di 2 k = cm2 [2]

5 © UCLES 2012 0653/52/M/J/12 [Turn over For Examiner's Use (iv) Use your values in (a)(ii) and (a)(iii) to calculate the volume V, in cm3, of the piece of pipe using the formula below. π k l 4 V = volume, V = cm3 [1] (v) Use your values in (a)(i) and (a)(iv) to calculate the density of the plastic in this piece of pipe, using the formula below. density = V M (method 1) density of plastic = g / cm3 [1]

6 © UCLES 2012 0653/52/M/J/12 For Examiner's Use (b) (i) Method 2 Exactly fill the 250 cm3 measuring cylinder with water up to the 150 cm3 mark. Attach the thread to the metal weight and lower it into the water until it is fully immersed. Read the new water level in the measuring cylinder and record the volume reading in Table 2.1. [1] Table 2.1 volume / cm3 water and metal weight water, metal weight and piece of pipe (ii) Remove the metal weight from the water, dry with a paper towel, and attach it to the piece of plastic pipe using the thread. If necessary, adjust the volume of water in the measuring cylinder to read exactly 150 cm3. Carefully lower the metal weight and piece of pipe into the water in the measuring cylinder until they are both fully immersed as in Fig. 2.2. Read the new water level in the measuring cylinder and record the volume reading in Table 2.1. measuring cylinder water pipe weight Fig. 2.2 [1]

7 © UCLES 2012 0653/52/M/J/12 [Turn over For Examiner's Use (iii) Using the volume readings in Table 2.1, calculate the volume of the material in the piece of pipe. volume of material in pipe = cm3 [1] (iv) Use your values in (a)(i) and (b)(iii) to calculate the density of the plastic in this piece of pipe. (method 2) density of plastic = g / cm3 [1]

8 © UCLES 2012 0653/52/M/J/12 For Examiner's Use 3 You are going to find out how much heat is produced in the reaction between solid A and solution B. (a) (i) Using the thermometer measure the temperature of solution B. Record the value to the nearest half degree, in Table 3.1 in the appropriate space, for time = 0 min. [1] Table 3.1 time / min temperature / °C 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 (ii) ● Place all of the solid A into the plastic cup. • Using the measuring cylinder measure out 25 cm3 of solution B. Add this quickly to solid A in the plastic cup. Start the stopclock. • Stir the mixture thoroughly. • Measure the temperature of the mixture every half minute for seven minutes, stirring throughout and recording the values to the nearest half degree in Table 3.1. [2] (iii) Record any changes to the appearance of the solid and to the solution in Table 3.2. Table 3.2 observations solid A solution B before the reaction grey blue after the reaction [2]

9 © UCLES 2012 0653/52/M/J/12 For Examiner's Use (b) (i) Using the data in Table 3.1, plot a graph of temperature (vertical axis) against time on the grid provided. Draw a smooth curve through the points. 1.0 2.0 3.0 4.0 5.0 0.5 0 1.5 2.5 3.5 4.5 6.0 7.0 5.5 6.5 60 50 40 30 20 10 0 temperature / °C time / min [2] (ii) Use your graph to find the maximum temperature rise, ∆T, in this reaction. ∆T = °C [1] (iii) Calculate E, the energy given out by the reaction using the formula below. E = volume of solution B × 4.2 × ∆T E = J [2]

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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. University of 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 2012 0653/52/M/J/12 CHEMISTRY PRACTICAL NOTES 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

UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS International General Certificate of Secondary Education MARK SCHEME for the May/June 2012 question paper for the guidance of teachers 0653 COMBINED SCIENCE 0653/52 Paper 5 (Practical Test), maximum raw mark 30 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 must be read in conjunction with the question papers and the report on the examination. • Cambridge will not enter into discussions or correspondence in connection with these mark schemes. Cambridge is publishing the mark schemes for the May/June 2012 question papers for most IGCSE, GCE Advanced Level and Advanced Subsidiary Level syllabuses and some Ordinary Level syllabuses. www.XtremePapers.com

Page 2 Mark Scheme: Teachers’ version Syllabus Paper IGCSE – May/June 2012 0653 52 © University of Cambridge International Examinations 2012 1 (a) tube A – no change ; tube B – time given in any format ; (not greater than 600 seconds) times given in seconds ; [3] (b) fatty acids neutralise the alkali / fatty acids react with sodium carbonate ; pH reduced to less than 8 / solution becomes acidic ; [2] (c) boiled lipase gave no result ; enzymes denature when heated ; [2] (allow reverse argument for both marks) (d) judging the end point / lack of repeats / measuring errors / any other valid suggestion ; [1] (e) tube C: purple / lilac ; tube C: protein present ; (do not award this mark if the colour in tube C is incorrect) [2] [Total: 10] 2 (a) (i) mass of piece of pipe, M, in grams to 1 decimal point and within 20% of supervisor ; [1] (ii) all 3 values of l, de and di AND de greater than di AND in cm ; [1] (iii) correct substitution ; correct calculation to 2 or more significant figures ; [2] (iv) correct calculation to 2 or more significant figures ; [1] (v) correct calculation to 2 or more significant figures ; [1] (b) (i) volume of water and metal weight ; [1] (ii) volume of water and metal weight and pipe ; (this must be greater than volume in (b) (i)) [1] (iii) volume of the piece of pipe ; [1] (iv) density within 0.5 of answer in (a)(v) ; [1] [Total: 10]

Page 3 Mark Scheme: Teachers’ version Syllabus Paper IGCSE – May/June 2012 0653 52 © University of Cambridge International Examinations 2012 3 (a) (i) time 0 = start temperature recorded to nearest half a degree ; [1] (ii) all readings entered to nearest half a degree ; maximum temperature achieved no more than 1 minute beyond supervisor’s time ; [2] (iii) solid A darker grey / black / brown / pink / red ; solution B paler blue / grey / colourless ; [2] (b) (i) points: at least 5 correctly plotted to within ½ square within the first 3 minutes ; line: smooth curve will include one maximum ; [2] (ii) maximum temp rise from graph , ∆T = max – start in °C ; [1] (iii) 25 × 4.2 × ans (b)(ii) ; correctly worked out to 2 or more significant figures ; [2] [Total: 10]