SENIOR CERTIFICATE EXAMINATIONS

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1 SENIOR ERTIFITE EXMINTIONS PYSIL SIENES: EMISTRY (P2) 2016 MRKS: 150 TIME: 3 hours This question paper consists of 15 pages and 4 data sheets. opyright reserved

2 Physical Sciences/P2 2 E/2016 SE INSTRUTIONS N INFORMTION Write your centre number and examination number in the appropriate spaces on the NSWER OOK. This question paper consists of TEN questions. nswer LL the questions in the NSWER OOK. Start E question on a NEW page in the NSWER OOK. Number the answers correctly according to the numbering system used in this question paper. Leave ONE line between two subquestions, for example between QUESTION 2.1 and QUESTION 2.2. You may use a non-programmable calculator. You may use appropriate mathematical instruments. You are advised to use the attached T SEETS. Show LL formulae and substitutions in LL calculations. Round off your final numerical answers to a minimum of TWO decimal places. Give brief motivations, discussions, et cetera where required. Write neatly and legibly. opyright reserved

3 Physical Sciences/P2 3 E/2016 SE QUESTION 1: MULTIPLE-OIE QUESTIONS Four options are provided as possible answers to the following questions. Each question has only ONE correct answer. hoose the answer and write only the letter ( ) next to the question number ( ) in the NSWER OOK, for example 1.11 E. 1.1 compound with the general formula n 2n+2 is an... alkane. alkene. alkyne. alcohol. (2) 1.2 Which ONE of the following is a product in LL neutralisation reactions? + 2 O O Nal (2) 1.3 Which ONE of the following pairs of products is formed during the catalytic oxidation of ammonia? NO 2 and 2 O NO and 2 O NO and NO 2 2 O and NO 3 (2) opyright reserved

4 Physical Sciences/P2 4 E/2016 SE 1.4 onsider the following potential energy diagram for a chemical reaction: 120 Potential energy (kj mol -1 ) ourse of reaction Which ONE of the following shows the values of the total energy change and the activation energy for this reaction? Energy change (kj mol -1 ) ctivation energy (kj mol -1 ) (2) 1.5 Which ONE of the following is a functional isomer of butanoic acid? O O O 3 3 O O O 2 3 O (2) opyright reserved

5 Physical Sciences/P2 5 E/2016 SE 1.6 In the flow diagram below P and Q represent two organic compounds. 2 2 r P NaO(aq) heat Q (major product) ompound Q is: r 3 2 O (2) 1.7 hromate ions and dichromate ions are in equilibrium with each other in an aqueous solution according to the following balanced equation: 2 2rO4 (aq) yellow (aq) r2o7 (aq) orange + 2 O (l) Which ONE of the following reagents should be added to change the colour of the solution to yellow? NO 3 l NaO 3 OO (2) 1.8 Which ONE of the following is a NON-SPONTNEOUS redox reaction? Refer to the Table of Standard Reduction Potentials (Table 4 or 4). Zn(s) + 2l(aq) Znl 2 (aq) + 2 (g) u(s) + Fel 2 (aq) ul 2 (aq) + Fe(s) 2gNO 3 (aq) + u(s) u(no 3 ) 2 (aq) + 2g(s) 2l(s) + 3Ni(NO 3 ) 2 (aq) 2l(NO 3 ) 3 (aq) + 3Ni(s) (2) opyright reserved

6 Physical Sciences/P2 6 E/2016 SE 1.9 In the electrochemical cell below the letters X and Y represent two metal electrodes. V Electrode X Electrode Y When the cell is functioning, ELETROE X GINS MSS. Which ONE of the following is the ORRET cell notation for this cell? Y(s) Y 2+ (aq) X + (aq) X(s) X(s) X + (aq) Y 2+ (aq) Y(s) X + (aq) X(s) Y(s) Y 2+ (aq) Y 2+ (aq) Y(s) X(s) X + (aq) (2) 1.10 Graph Q (the solid line) below was obtained for the reaction of 100 cm 3 of a 0,1 mol dm -3 l solution with excess magnesium powder. Which graph (,, or ) most probably represents the reaction of 100 cm 3 of a 0,1 mol dm -3 3 OO solution with excess magnesium powder? Volume 2 gas produced (cm 3 ) Q Time (s) (2) [20] opyright reserved

7 Physical Sciences/P2 7 E/2016 SE QUESTION 2 (Start on a new page.) onsider the organic compounds to F below O 2,2-dimethylpropane O E O F 3 ( 3 ) Write down the LETTER that represents a compound that: as a carbonyl group (1) Is an alcohol (1) Is a IN ISOMER of 3 ( 2 ) 3 3 (1) 2.2 Write down the: IUP name of compound (2) Structural formula of compound F (2) IUP name of a POSITIONL isomer of compound (3) 2.3 ompound E is formed when a carboxylic acid reacts with another organic compound. Write down the: omologous series to which compound E belongs (1) NME or FORMUL of the catalyst used for the preparation of compound E (1) IUP name of compound E (2) [14] opyright reserved

8 Physical Sciences/P2 8 E/2016 SE QUESTION 3 (Start on a new page.) The relationship between boiling point and the number of carbon atoms in straight chain molecules of alkanes, carboxylic acids and alcohols is investigated. urves P, Q and R are obtained. GRP OF OILING POINT VERSUS NUMER OF TOMS oiling point (K) urve R urve Q urve P Number of atoms 3.1 efine the term boiling point. (2) 3.2 For curve P, write down a conclusion that can be drawn from the above results. (2) 3.3 Identify the curve (P, Q or R) that represents each of the following: lkanes (1) arboxylic acids (1) 3.4 Explain the answer to QUESTION by referring to the: Types of intermolecular forces present in alkanes, carboxylic acids and alcohols Relative strengths of these intermolecular forces Energy needed (5) [11] opyright reserved

9 Physical Sciences/P2 9 E/2016 SE QUESTION 4 (Start on a new page.) The flow diagram below shows how prop-1-ene can be used to prepare other organic compounds. propane compound X (major product) r prop-1-ene alcohol (major product) E F 4.1 Write down the type of reaction represented by: F (1) (1) (1) 4.2 Write down the: NME or FORMUL of the catalyst needed for reaction (1) NME or FORMUL of the inorganic reagent needed for reaction (1) Type of addition reaction represented by reaction (1) IUP name of compound X (2) 4.3 Use structural formulae to write down a balanced equation for reaction. (5) 4.4 oth reactions and E take place in the presence of a strong base. State TWO conditions that will favour reaction over reaction E. (2) [15] opyright reserved

10 Physical Sciences/P2 10 E/2016 SE QUESTION 5 (Start on a new page.) The reaction between dilute hydrochloric acid and sodium thiosulphate (Na 2 S 2 O 3 ) is used to investigate one of the factors that influences reaction rate. The balanced equation for the reaction is: Na 2 S 2 O 3 (aq) + 2l(aq) 2Nal(aq) + S(s) + 2 O(l) + SO 2 (g) The hydrochloric acid solution is added to the sodium thiosulphate solution in a flask. The flask is placed over a cross drawn on a sheet of white paper, as shown in the diagram below. The time that it takes for the cross to become invisible is measured to determine the reaction rate. flask Na 2 S 2 O 3 (aq) + l(aq) white paper Four experiments, to, are conducted during this investigation. The volumes of reactants used in each of the four experiments and the times of the reactions are summarised in the table below. Experiment opyright reserved Volume of Na 2 S 2 O 3 (aq) (cm 3 ) Volume of 2 O(l) (cm 3 ) Volume of l(aq) (cm 3 ) Time (s) , , , ,0 5.1 State TWO factors that can influence the rate of the reaction above. (2) 5.2 Write down the NME or FORMUL of the product that causes the cross to become invisible. (1) 5.3 Give a reason why water is added to the reaction mixture in experiments to. (1) 5.4 Write down an investigative question for this investigation. (2) 5.5 In which experiment (,, or ) is the reaction rate the highest? (1) 5.6 Use the collision theory to explain the difference in reaction rate between experiments and. (3) 5.7 The original Na 2 S 2 O 3 solution was prepared by dissolving 62,50 g Na 2 S 2 O 3 crystals in distilled water in a 250 cm 3 volumetric flask. alculate the mass of sulphur, S, that will form in experiment if Na 2 S 2 O 3 is the limiting reactant. (7) [17]

11 Physical Sciences/P2 11 E/2016 SE QUESTION 6 (Start on a new page.) arbon dioxide reacts with carbon in a closed system to produce carbon monoxide, O(g), according to the following balanced equation: O 2 (g) + (s) 2O(g) Δ > What does the double arrow indicate in the equation above? (1) 6.2 Is the above reaction an EXOTERMI reaction or an ENOTERMI reaction? Give a reason for the answer. (2) Initially an unknown amount of carbon dioxide is exposed to hot carbon at 800 in a sealed 2 dm 3 container. The equilibrium constant, K c, for the reaction at this temperature is 14. t equilibrium it is found that 168,00 g carbon monoxide is present. 6.3 ow will the equilibrium concentration of the product compare to that of the reactants? hoose from LRGER TN, SMLLER TN or EQUL TO. Give a reason for the answer. (No calculation is required.) (2) 6.4 alculate the initial amount (in moles) of O 2 (g) present. (9) 6.5 State how E of the following will affect the yield of O(g) at equilibrium. hoose from INRESES, ERESES or REMINS TE SME More carbon is added at constant temperature. (1) The pressure is increased. (1) The temperature is increased. (1) [17] opyright reserved

12 Physical Sciences/P2 12 E/2016 SE QUESTION 7 (Start on a new page.) 7.1 ydrogen carbonate ions react with water according to the following balanced equation: O 3 (aq) + 2 O(l) 2 O 3 (aq) + O (aq) efine an acid according to the Lowry-rønsted theory. (2) Write down the FORMULE of the two acids in the equation above. (2) Write down the formula of a substance in the reaction above that can act as an ampholyte. (1) 7.2 uring an experiment 0,50 dm 3 of a 0,10 mol dm -3 l solution is added to 0,80 dm 3 of a NaO 3 solution of concentration 0,25 mol dm -3. The balanced equation for the reaction is: alculate the: NaO 3 (aq) + l(aq) Nal(aq) + O 2 (g) + 2 O(l) oncentration of the hydroxide ions in the solution on completion of the reaction (8) p of the solution on completion of the reaction (4) [17] opyright reserved

13 Physical Sciences/P2 13 E/2016 SE QUESTION 8 (Start on a new page.) Magnesium (Mg) reacts with a dilute hydrochloric acid solution, l(aq), according to the following balanced equation: Mg(s) + 2l(aq) Mgl 2 (aq) + 2 (g) 8.1 Give a reason why the reaction above is a redox reaction. (1) 8.2 Write down the FORMUL of the oxidising agent in the reaction above. (1) It is found that silver does not react with the hydrochloric acid solution. 8.3 Refer to the relative strengths of reducing agents to explain this observation. (3) The reaction of magnesium with hydrochloric acid is used in an electrochemical cell, as shown in the diagram below. The cell functions under standard conditions. V hydrogen gas Q Mg platinum 1 mol dm -3 + (aq) Mg 2+ (aq) half-cell half-cell 8.4 What is the function of platinum in the cell above? (1) 8.5 Write down the: Energy conversion that takes place in this cell (1) Function of Q (1) alf-reaction that takes place at the cathode (2) ell notation of this cell (3) 8.6 alculate the initial emf of this cell. (4) 8.7 ow will the addition of concentrated acid to half-cell influence the answer to QUESTION 8.6? hoose from INRESES, ERESES or REMINS TE SME. (1) [18] opyright reserved

14 Physical Sciences/P2 14 E/2016 SE QUESTION 9 (Start on a new page.) The diagram below shows an electrochemical cell used to purify copper. solution that conducts electricity is used in the cell. 9.1 Write down: ONE word for the underlined phrase above the diagram (1) The type of electrochemical cell illustrated above (1) 9.2 In which direction (from to or from to ) will electrons flow in the external circuit? (1) 9.3 Which electrode ( or ) is the: athode (1) Impure copper (1) 9.4 ow will the mass of electrode change as the reaction proceeds? hoose from INRESES, ERESES or REMINS TE SME. Give a reason for the answer. (2) [7] opyright reserved

15 Physical Sciences/P2 15 E/2016 SE QUESTION 10 (Start on a new page.) chemical company produces ammonium sulphate, (N 4 ) 2 SO 4, starting from the raw materials P, Q and R, as shown in the flow diagram below. P Q R SO 2 (g) nitrogen hydrogen SO 3 (g) process 1 oleum reaction 1 compound X compound Y (N 4 ) 2 SO Write down the NME of raw material: P Q R (1) (1) (1) 10.2 Write down the: opyright reserved NME of process 1 (1) NME of compound X (1) FORMUL of compound Y (1) alanced equation for reaction 1 (3) 10.3 The company compares the nitrogen content of ammonium sulphate with that of ammonium nitrate, N 4 NO etermine, by performing the necessary calculations, which ONE of the two fertilisers has the higher percentage of nitrogen per mass. (4) Write down the name of the process that should be included in the flow diagram above if the company wants to prepare ammonium nitrate instead of ammonium sulphate. (1) [14] TOTL: 150

16 Physical Sciences/P2 1 E/2016 SE T FOR PYSIL SIENES GRE 12 PPER 2 (EMISTRY) GEGEWENS VIR FISIESE WETENSKPPE GR 12 VRESTEL 2 (EMIE) TLE 1: PYSIL ONSTNTS/TEL 1: FISIESE KONSTNTES NME/NM SYMOL/SIMOOL VLUE/WRE Standard pressure Standaarddruk p 1,013 x 10 5 Pa Molar gas volume at STP Molêre gasvolume by ST V m 22,4 dm 3 mol -1 Standard temperature Standaardtemperatuur T 273 K harge on electron Lading op elektron e -1,6 x vogadro's constant vogadro-konstante N 6,02 x mol -1 TLE 2: FORMULE/TEL 2: FORMULES m n= M n c = V cava c v b n or/of m c = MV n= n= a = p = -log[ b n 3 O + ] b K w = [ 3 O + ][O - ] = 1 x at/by 298 K N N V V m E cell = E E / E = E E cathode anode sel katode anode or/of E = E E / E = E E cell reduction oxidation sel reduksie oksidasie or/of E = E E / E = E E cell oxidising agent reducing agent sel oksideermiddel reduseermiddel opyright reserved

17 Physical Sciences/P2 2 E/2016 SE opyright reserved TLE 3: TE PERIOI TLE OF ELEMENTS TEL 3: IE PERIOIEKE TEL VN ELEMENTE 1 (I) 2 (II) (III) 14 (IV) 15 (V) 16 (VI) 17 (VII) 18 (VIII) 2, e 4 1,0 3 Li 7 1,5 4 e 9 2, , ,0 7 N 14 3,5 8 O 16 4,0 9 F Ne 20 0,9 11 Na 23 1,2 12 Mg 24 1,5 13 l 27 1,8 14 Si 28 2,1 15 P 31 2,5 16 S 32 3,0 17 l 35,5 18 r 40 0,8 19 K 39 1,0 20 a 40 1,3 21 Sc 45 1,5 22 Ti 48 1,6 23 V 51 1,6 24 r 52 1,5 25 Mn 55 1,8 26 Fe 56 1,8 27 o 59 1,8 28 Ni 59 1,9 29 u 63,5 1,6 30 Zn 65 1,6 31 Ga 70 1,8 32 Ge 73 2,0 33 s 75 2,4 34 Se 79 2,8 35 r Kr 84 0,8 37 Rb 86 1,0 38 Sr 88 1,2 39 Y 89 1,4 40 Zr Nb 92 1,8 42 Mo 96 1,9 43 Tc 2,2 44 Ru 101 2,2 45 Rh 103 2,2 46 Pd 106 1,9 47 g 108 1,7 48 d 112 1,7 49 In 115 1,8 50 Sn 119 1,9 51 Sb 122 2,1 52 Te 128 2,5 53 I Xe 131 0,7 55 s 133 0,9 56 a La 139 1,6 72 f Ta W Re Os Ir Pt u g 201 1,8 81 Tl 204 1,8 82 Pb 207 1,9 83 i 209 2,0 84 Po 2,5 85 t 86 Rn 0,7 87 Fr 0,9 88 Ra c 58 e Pr Nd Pm 62 Sm Eu Gd Tb y o Er Tm Yb Lu Th Pa 92 U Np 94 Pu 95 m 96 m 97 k 98 f 99 Es 100 Fm 101 Md 102 No 103 Lr Electronegativity Elektronegatiwiteit pproximate relative atomic mass enaderde relatiewe atoommassa tomic number toomgetal 29 u 63,5 1,9 Symbol Simbool KEY/SLEUTEL

18 Physical Sciences/P2 3 E/2016 SE TLE 4: STNR REUTION POTENTILS TEL 4: STNR-REUKSIEPOTENSILE Increasing oxidising ability/toenemende oksiderende vermoë opyright reserved alf-reactions/alfreaksies E (V) F 2(g) + 2e 2F + 2,87 o 3+ + e o ,81 2O e 2 2O +1,77 MnO e Mn O + 1,51 l 2(g) + 2e 2l + 1,36 r 2O e 2r O + 1,33 O 2(g) e 2 2O + 1,23 MnO e Mn O + 1,23 Pt e Pt + 1,20 r 2(l) + 2e 2r + 1,07 NO e NO(g) + 2 2O + 0,96 g e g(l) + 0,85 g + + e g + 0,80 NO e NO 2(g) + 2O + 0,80 Fe 3+ + e Fe ,77 O 2(g) e 2O 2 + 0,68 I 2 + 2e 2I + 0,54 u + + e u + 0,52 SO e S + 2 2O + 0,45 2 2O + O 2 + 4e 4O + 0,40 u e u + 0,34 SO e SO 2(g) + 2 2O + 0,17 u 2+ + e u + + 0,16 Sn e Sn ,15 S e 2S(g) + 0, e 2(g) 0,00 Fe e Fe 0,06 Pb e Pb 0,13 Sn e Sn 0,14 Ni e Ni 0,27 o e o 0,28 d e d 0,40 r 3+ + e r 2+ 0,41 Fe e Fe 0,44 r e r 0,74 Zn e Zn 0,76 2 2O + 2e 2(g) + 2O 0,83 r e r 0,91 Mn e Mn 1,18 l e l 1,66 Mg e Mg 2,36 Na + + e Na 2,71 a e a 2,87 Sr e Sr 2,89 a e a 2,90 s + + e - s - 2,92 K + + e K 2,93 Li + + e Li 3,05 Increasing reducing ability/toenemende reduserende vermoë

19 E Physical Sciences/P2 4 E/2016 SE TLE 4: STNR REUTION POTENTILS TEL 4: STNR-REUKSIEPOTENSILE alf-reactions/alfreaksies (V) Li + + e Li 3,05 K + + e K 2,93 s + + e s 2,92 a e a 2,90 Sr e Sr 2,89 a e a 2,87 Na + + e Na 2,71 Mg e Mg 2,36 l e l 1,66 Mn e Mn 1,18 r e r 0,91 2 2O + 2e 2(g) + 2O 0,83 Zn e Zn 0,76 r e r 0,74 Fe e Fe 0,44 r 3+ + e r 2+ 0,41 d e d 0,40 o e o 0,28 Ni e Ni 0,27 Sn e Sn 0,14 Pb e Pb 0,13 Fe e Fe 0, e 2(g) 0,00 S e 2S(g) + 0,14 Sn e Sn ,15 u 2+ + e u + + 0,16 SO e SO 2(g) + 2 2O + 0,17 Increasing oxidising ability/toenemende oksiderende vermoë opyright reserved u e u + 0,34 2 2O + O 2 + 4e 4O + 0,40 SO e S + 2 2O + 0,45 u + + e u + 0,52 I 2 + 2e 2I + 0,54 O 2(g) e 2O 2 + 0,68 Fe 3+ + e Fe ,77 NO e NO 2(g) + 2O + 0,80 g + + e g + 0,80 g e g(l) + 0,85 NO e NO(g) + 2 2O + 0,96 r 2(l) + 2e 2r + 1,07 Pt e Pt + 1,20 MnO e Mn O + 1,23 O 2(g) e 2 2O + 1,23 r 2O e 2r O + 1,33 l 2(g) + 2e 2l + 1,36 MnO e Mn O + 1,51 2O e 2 2O +1,77 o 3+ + e o ,81 F 2(g) + 2e 2F + 2,87 Increasing reducing ability/toenemende reduserende vermoë